<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/arch/powerpc/kernel/process.c, branch v5.4.239</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>powerpc: Enable execve syscall exit tracepoint</title>
<updated>2022-06-29T06:58:48+00:00</updated>
<author>
<name>Naveen N. Rao</name>
<email>naveen.n.rao@linux.vnet.ibm.com</email>
</author>
<published>2022-06-09T10:33:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b6232979320a4c5b493a2f9b93144e5c240d7315'/>
<id>b6232979320a4c5b493a2f9b93144e5c240d7315</id>
<content type='text'>
commit ec6d0dde71d760aa60316f8d1c9a1b0d99213529 upstream.

On execve[at], we are zero'ing out most of the thread register state
including gpr[0], which contains the syscall number. Due to this, we
fail to trigger the syscall exit tracepoint properly. Fix this by
retaining gpr[0] in the thread register state.

Before this patch:
  # tail /sys/kernel/debug/tracing/trace
	       cat-123     [000] .....    61.449351: sys_execve(filename:
  7fffa6b23448, argv: 7fffa6b233e0, envp: 7fffa6b233f8)
	       cat-124     [000] .....    62.428481: sys_execve(filename:
  7fffa6b23448, argv: 7fffa6b233e0, envp: 7fffa6b233f8)
	      echo-125     [000] .....    65.813702: sys_execve(filename:
  7fffa6b23378, argv: 7fffa6b233a0, envp: 7fffa6b233b0)
	      echo-125     [000] .....    65.822214: sys_execveat(fd: 0,
  filename: 1009ac48, argv: 7ffff65d0c98, envp: 7ffff65d0ca8, flags: 0)

After this patch:
  # tail /sys/kernel/debug/tracing/trace
	       cat-127     [000] .....   100.416262: sys_execve(filename:
  7fffa41b3448, argv: 7fffa41b33e0, envp: 7fffa41b33f8)
	       cat-127     [000] .....   100.418203: sys_execve -&gt; 0x0
	      echo-128     [000] .....   103.873968: sys_execve(filename:
  7fffa41b3378, argv: 7fffa41b33a0, envp: 7fffa41b33b0)
	      echo-128     [000] .....   103.875102: sys_execve -&gt; 0x0
	      echo-128     [000] .....   103.882097: sys_execveat(fd: 0,
  filename: 1009ac48, argv: 7fffd10d2148, envp: 7fffd10d2158, flags: 0)
	      echo-128     [000] .....   103.883225: sys_execveat -&gt; 0x0

Cc: stable@vger.kernel.org
Signed-off-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Tested-by: Sumit Dubey2 &lt;Sumit.Dubey2@ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220609103328.41306-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit ec6d0dde71d760aa60316f8d1c9a1b0d99213529 upstream.

On execve[at], we are zero'ing out most of the thread register state
including gpr[0], which contains the syscall number. Due to this, we
fail to trigger the syscall exit tracepoint properly. Fix this by
retaining gpr[0] in the thread register state.

Before this patch:
  # tail /sys/kernel/debug/tracing/trace
	       cat-123     [000] .....    61.449351: sys_execve(filename:
  7fffa6b23448, argv: 7fffa6b233e0, envp: 7fffa6b233f8)
	       cat-124     [000] .....    62.428481: sys_execve(filename:
  7fffa6b23448, argv: 7fffa6b233e0, envp: 7fffa6b233f8)
	      echo-125     [000] .....    65.813702: sys_execve(filename:
  7fffa6b23378, argv: 7fffa6b233a0, envp: 7fffa6b233b0)
	      echo-125     [000] .....    65.822214: sys_execveat(fd: 0,
  filename: 1009ac48, argv: 7ffff65d0c98, envp: 7ffff65d0ca8, flags: 0)

After this patch:
  # tail /sys/kernel/debug/tracing/trace
	       cat-127     [000] .....   100.416262: sys_execve(filename:
  7fffa41b3448, argv: 7fffa41b33e0, envp: 7fffa41b33f8)
	       cat-127     [000] .....   100.418203: sys_execve -&gt; 0x0
	      echo-128     [000] .....   103.873968: sys_execve(filename:
  7fffa41b3378, argv: 7fffa41b33a0, envp: 7fffa41b33b0)
	      echo-128     [000] .....   103.875102: sys_execve -&gt; 0x0
	      echo-128     [000] .....   103.882097: sys_execveat(fd: 0,
  filename: 1009ac48, argv: 7fffd10d2148, envp: 7fffd10d2158, flags: 0)
	      echo-128     [000] .....   103.883225: sys_execveat -&gt; 0x0

Cc: stable@vger.kernel.org
Signed-off-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Tested-by: Sumit Dubey2 &lt;Sumit.Dubey2@ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220609103328.41306-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/kasan: Silence KASAN warnings in __get_wchan()</title>
<updated>2022-06-22T12:11:19+00:00</updated>
<author>
<name>He Ying</name>
<email>heying24@huawei.com</email>
</author>
<published>2022-01-21T01:44:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=348831a9e8aa311e6fb09ce8748b8ed29e73cf05'/>
<id>348831a9e8aa311e6fb09ce8748b8ed29e73cf05</id>
<content type='text'>
[ Upstream commit a1b29ba2f2c171b9bea73be993bfdf0a62d37d15 ]

The following KASAN warning was reported in our kernel.

  BUG: KASAN: stack-out-of-bounds in get_wchan+0x188/0x250
  Read of size 4 at addr d216f958 by task ps/14437

  CPU: 3 PID: 14437 Comm: ps Tainted: G           O      5.10.0 #1
  Call Trace:
  [daa63858] [c0654348] dump_stack+0x9c/0xe4 (unreliable)
  [daa63888] [c035cf0c] print_address_description.constprop.3+0x8c/0x570
  [daa63908] [c035d6bc] kasan_report+0x1ac/0x218
  [daa63948] [c00496e8] get_wchan+0x188/0x250
  [daa63978] [c0461ec8] do_task_stat+0xce8/0xe60
  [daa63b98] [c0455ac8] proc_single_show+0x98/0x170
  [daa63bc8] [c03cab8c] seq_read_iter+0x1ec/0x900
  [daa63c38] [c03cb47c] seq_read+0x1dc/0x290
  [daa63d68] [c037fc94] vfs_read+0x164/0x510
  [daa63ea8] [c03808e4] ksys_read+0x144/0x1d0
  [daa63f38] [c005b1dc] ret_from_syscall+0x0/0x38
  --- interrupt: c00 at 0x8fa8f4
      LR = 0x8fa8cc

  The buggy address belongs to the page:
  page:98ebcdd2 refcount:0 mapcount:0 mapping:00000000 index:0x2 pfn:0x1216f
  flags: 0x0()
  raw: 00000000 00000000 01010122 00000000 00000002 00000000 ffffffff 00000000
  raw: 00000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   d216f800: 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 00 00
   d216f880: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  &gt;d216f900: 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00
                                            ^
   d216f980: f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00 00
   d216fa00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

After looking into this issue, I find the buggy address belongs
to the task stack region. It seems KASAN has something wrong.
I look into the code of __get_wchan in x86 architecture and
find the same issue has been resolved by the commit
f7d27c35ddff ("x86/mm, kasan: Silence KASAN warnings in get_wchan()").
The solution could be applied to powerpc architecture too.

As Andrey Ryabinin said, get_wchan() is racy by design, it may
access volatile stack of running task, thus it may access
redzone in a stack frame and cause KASAN to warn about this.

Use READ_ONCE_NOCHECK() to silence these warnings.

Reported-by: Wanming Hu &lt;huwanming@huaweil.com&gt;
Signed-off-by: He Ying &lt;heying24@huawei.com&gt;
Signed-off-by: Chen Jingwen &lt;chenjingwen6@huawei.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220121014418.155675-1-heying24@huawei.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit a1b29ba2f2c171b9bea73be993bfdf0a62d37d15 ]

The following KASAN warning was reported in our kernel.

  BUG: KASAN: stack-out-of-bounds in get_wchan+0x188/0x250
  Read of size 4 at addr d216f958 by task ps/14437

  CPU: 3 PID: 14437 Comm: ps Tainted: G           O      5.10.0 #1
  Call Trace:
  [daa63858] [c0654348] dump_stack+0x9c/0xe4 (unreliable)
  [daa63888] [c035cf0c] print_address_description.constprop.3+0x8c/0x570
  [daa63908] [c035d6bc] kasan_report+0x1ac/0x218
  [daa63948] [c00496e8] get_wchan+0x188/0x250
  [daa63978] [c0461ec8] do_task_stat+0xce8/0xe60
  [daa63b98] [c0455ac8] proc_single_show+0x98/0x170
  [daa63bc8] [c03cab8c] seq_read_iter+0x1ec/0x900
  [daa63c38] [c03cb47c] seq_read+0x1dc/0x290
  [daa63d68] [c037fc94] vfs_read+0x164/0x510
  [daa63ea8] [c03808e4] ksys_read+0x144/0x1d0
  [daa63f38] [c005b1dc] ret_from_syscall+0x0/0x38
  --- interrupt: c00 at 0x8fa8f4
      LR = 0x8fa8cc

  The buggy address belongs to the page:
  page:98ebcdd2 refcount:0 mapcount:0 mapping:00000000 index:0x2 pfn:0x1216f
  flags: 0x0()
  raw: 00000000 00000000 01010122 00000000 00000002 00000000 ffffffff 00000000
  raw: 00000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   d216f800: 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 00 00
   d216f880: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  &gt;d216f900: 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00
                                            ^
   d216f980: f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00 00
   d216fa00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

After looking into this issue, I find the buggy address belongs
to the task stack region. It seems KASAN has something wrong.
I look into the code of __get_wchan in x86 architecture and
find the same issue has been resolved by the commit
f7d27c35ddff ("x86/mm, kasan: Silence KASAN warnings in get_wchan()").
The solution could be applied to powerpc architecture too.

As Andrey Ryabinin said, get_wchan() is racy by design, it may
access volatile stack of running task, thus it may access
redzone in a stack frame and cause KASAN to warn about this.

Use READ_ONCE_NOCHECK() to silence these warnings.

Reported-by: Wanming Hu &lt;huwanming@huaweil.com&gt;
Signed-off-by: He Ying &lt;heying24@huawei.com&gt;
Signed-off-by: Chen Jingwen &lt;chenjingwen6@huawei.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220121014418.155675-1-heying24@huawei.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/64: Fix stack trace not displaying final frame</title>
<updated>2021-03-17T16:03:43+00:00</updated>
<author>
<name>Michael Ellerman</name>
<email>mpe@ellerman.id.au</email>
</author>
<published>2021-02-09T13:59:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d92afe30a665ce6a3cfd950d5d67ce30cdf682fd'/>
<id>d92afe30a665ce6a3cfd950d5d67ce30cdf682fd</id>
<content type='text'>
[ Upstream commit e3de1e291fa58a1ab0f471a4b458eff2514e4b5f ]

In commit bf13718bc57a ("powerpc: show registers when unwinding
interrupt frames") we changed our stack dumping logic to show the full
registers whenever we find an interrupt frame on the stack.

However we didn't notice that on 64-bit this doesn't show the final
frame, ie. the interrupt that brought us in from userspace, whereas on
32-bit it does.

That is due to confusion about the size of that last frame. The code
in show_stack() calls validate_sp(), passing it STACK_INT_FRAME_SIZE
to check the sp is at least that far below the top of the stack.

However on 64-bit that size is too large for the final frame, because
it includes the red zone, but we don't allocate a red zone for the
first frame.

So add a new define that encodes the correct size for 32-bit and
64-bit, and use it in show_stack().

This results in the full trace being shown on 64-bit, eg:

  sysrq: Trigger a crash
  Kernel panic - not syncing: sysrq triggered crash
  CPU: 0 PID: 83 Comm: sh Not tainted 5.11.0-rc2-gcc-8.2.0-00188-g571abcb96b10-dirty #649
  Call Trace:
  [c00000000a1c3ac0] [c000000000897b70] dump_stack+0xc4/0x114 (unreliable)
  [c00000000a1c3b00] [c00000000014334c] panic+0x178/0x41c
  [c00000000a1c3ba0] [c00000000094e600] sysrq_handle_crash+0x40/0x50
  [c00000000a1c3c00] [c00000000094ef98] __handle_sysrq+0xd8/0x210
  [c00000000a1c3ca0] [c00000000094f820] write_sysrq_trigger+0x100/0x188
  [c00000000a1c3ce0] [c0000000005559dc] proc_reg_write+0x10c/0x1b0
  [c00000000a1c3d10] [c000000000479950] vfs_write+0xf0/0x360
  [c00000000a1c3d60] [c000000000479d9c] ksys_write+0x7c/0x140
  [c00000000a1c3db0] [c00000000002bf5c] system_call_exception+0x19c/0x2c0
  [c00000000a1c3e10] [c00000000000d35c] system_call_common+0xec/0x278
  --- interrupt: c00 at 0x7fff9fbab428
  NIP:  00007fff9fbab428 LR: 000000001000b724 CTR: 0000000000000000
  REGS: c00000000a1c3e80 TRAP: 0c00   Not tainted  (5.11.0-rc2-gcc-8.2.0-00188-g571abcb96b10-dirty)
  MSR:  900000000280f033 &lt;SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE&gt;  CR: 22002884  XER: 00000000
  IRQMASK: 0
  GPR00: 0000000000000004 00007fffc3cb8960 00007fff9fc59900 0000000000000001
  GPR04: 000000002a4b32d0 0000000000000002 0000000000000063 0000000000000063
  GPR08: 000000002a4b32d0 0000000000000000 0000000000000000 0000000000000000
  GPR12: 0000000000000000 00007fff9fcca9a0 0000000000000000 0000000000000000
  GPR16: 0000000000000000 0000000000000000 0000000000000000 00000000100b8fd0
  GPR20: 000000002a4b3485 00000000100b8f90 0000000000000000 0000000000000000
  GPR24: 000000002a4b0440 00000000100e77b8 0000000000000020 000000002a4b32d0
  GPR28: 0000000000000001 0000000000000002 000000002a4b32d0 0000000000000001
  NIP [00007fff9fbab428] 0x7fff9fbab428
  LR [000000001000b724] 0x1000b724
  --- interrupt: c00

Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20210209141627.2898485-1-mpe@ellerman.id.au
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit e3de1e291fa58a1ab0f471a4b458eff2514e4b5f ]

In commit bf13718bc57a ("powerpc: show registers when unwinding
interrupt frames") we changed our stack dumping logic to show the full
registers whenever we find an interrupt frame on the stack.

However we didn't notice that on 64-bit this doesn't show the final
frame, ie. the interrupt that brought us in from userspace, whereas on
32-bit it does.

That is due to confusion about the size of that last frame. The code
in show_stack() calls validate_sp(), passing it STACK_INT_FRAME_SIZE
to check the sp is at least that far below the top of the stack.

However on 64-bit that size is too large for the final frame, because
it includes the red zone, but we don't allocate a red zone for the
first frame.

So add a new define that encodes the correct size for 32-bit and
64-bit, and use it in show_stack().

This results in the full trace being shown on 64-bit, eg:

  sysrq: Trigger a crash
  Kernel panic - not syncing: sysrq triggered crash
  CPU: 0 PID: 83 Comm: sh Not tainted 5.11.0-rc2-gcc-8.2.0-00188-g571abcb96b10-dirty #649
  Call Trace:
  [c00000000a1c3ac0] [c000000000897b70] dump_stack+0xc4/0x114 (unreliable)
  [c00000000a1c3b00] [c00000000014334c] panic+0x178/0x41c
  [c00000000a1c3ba0] [c00000000094e600] sysrq_handle_crash+0x40/0x50
  [c00000000a1c3c00] [c00000000094ef98] __handle_sysrq+0xd8/0x210
  [c00000000a1c3ca0] [c00000000094f820] write_sysrq_trigger+0x100/0x188
  [c00000000a1c3ce0] [c0000000005559dc] proc_reg_write+0x10c/0x1b0
  [c00000000a1c3d10] [c000000000479950] vfs_write+0xf0/0x360
  [c00000000a1c3d60] [c000000000479d9c] ksys_write+0x7c/0x140
  [c00000000a1c3db0] [c00000000002bf5c] system_call_exception+0x19c/0x2c0
  [c00000000a1c3e10] [c00000000000d35c] system_call_common+0xec/0x278
  --- interrupt: c00 at 0x7fff9fbab428
  NIP:  00007fff9fbab428 LR: 000000001000b724 CTR: 0000000000000000
  REGS: c00000000a1c3e80 TRAP: 0c00   Not tainted  (5.11.0-rc2-gcc-8.2.0-00188-g571abcb96b10-dirty)
  MSR:  900000000280f033 &lt;SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE&gt;  CR: 22002884  XER: 00000000
  IRQMASK: 0
  GPR00: 0000000000000004 00007fffc3cb8960 00007fff9fc59900 0000000000000001
  GPR04: 000000002a4b32d0 0000000000000002 0000000000000063 0000000000000063
  GPR08: 000000002a4b32d0 0000000000000000 0000000000000000 0000000000000000
  GPR12: 0000000000000000 00007fff9fcca9a0 0000000000000000 0000000000000000
  GPR16: 0000000000000000 0000000000000000 0000000000000000 00000000100b8fd0
  GPR20: 000000002a4b3485 00000000100b8f90 0000000000000000 0000000000000000
  GPR24: 000000002a4b0440 00000000100e77b8 0000000000000020 000000002a4b32d0
  GPR28: 0000000000000001 0000000000000002 000000002a4b32d0 0000000000000001
  NIP [00007fff9fbab428] 0x7fff9fbab428
  LR [000000001000b724] 0x1000b724
  --- interrupt: c00

Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20210209141627.2898485-1-mpe@ellerman.id.au
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc: Fix kernel crash in show_instructions() w/DEBUG_VIRTUAL</title>
<updated>2020-06-24T15:50:45+00:00</updated>
<author>
<name>Aneesh Kumar K.V</name>
<email>aneesh.kumar@linux.ibm.com</email>
</author>
<published>2020-05-24T09:38:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7b307d292ab26ef6a9b85754a608aa2b5b607318'/>
<id>7b307d292ab26ef6a9b85754a608aa2b5b607318</id>
<content type='text'>
[ Upstream commit a6e2c226c3d51fd93636320e47cabc8a8f0824c5 ]

With CONFIG_DEBUG_VIRTUAL=y, we can hit a BUG() if we take a hard
lockup watchdog interrupt when in OPAL mode.

This happens in show_instructions() if the kernel takes the watchdog
NMI IPI, or any other interrupt, with MSR_IR == 0. show_instructions()
updates the variable pc in the loop and the second iteration will
result in BUG().

We hit the BUG_ON due the below check in  __va()

  #define __va(x)
  ({
  	VIRTUAL_BUG_ON((unsigned long)(x) &gt;= PAGE_OFFSET);
  	(void *)(unsigned long)((phys_addr_t)(x) | PAGE_OFFSET);
  })

Fix it by moving the check out of the loop. Also update nip so that
the nip == pc check still matches.

Fixes: 4dd7554a6456 ("powerpc/64: Add VIRTUAL_BUG_ON checks for __va and __pa addresses")
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
[mpe: Use IS_ENABLED(), massage change log]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20200524093822.423487-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit a6e2c226c3d51fd93636320e47cabc8a8f0824c5 ]

With CONFIG_DEBUG_VIRTUAL=y, we can hit a BUG() if we take a hard
lockup watchdog interrupt when in OPAL mode.

This happens in show_instructions() if the kernel takes the watchdog
NMI IPI, or any other interrupt, with MSR_IR == 0. show_instructions()
updates the variable pc in the loop and the second iteration will
result in BUG().

We hit the BUG_ON due the below check in  __va()

  #define __va(x)
  ({
  	VIRTUAL_BUG_ON((unsigned long)(x) &gt;= PAGE_OFFSET);
  	(void *)(unsigned long)((phys_addr_t)(x) | PAGE_OFFSET);
  })

Fix it by moving the check out of the loop. Also update nip so that
the nip == pc check still matches.

Fixes: 4dd7554a6456 ("powerpc/64: Add VIRTUAL_BUG_ON checks for __va and __pa addresses")
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
[mpe: Use IS_ENABLED(), massage change log]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20200524093822.423487-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'powerpc-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux</title>
<updated>2019-09-20T18:48:06+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-09-20T18:48:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=45824fc0da6e46cc5d563105e1eaaf3098a686f9'/>
<id>45824fc0da6e46cc5d563105e1eaaf3098a686f9</id>
<content type='text'>
Pull powerpc updates from Michael Ellerman:
 "This is a bit late, partly due to me travelling, and partly due to a
  power outage knocking out some of my test systems *while* I was
  travelling.

   - Initial support for running on a system with an Ultravisor, which
     is software that runs below the hypervisor and protects guests
     against some attacks by the hypervisor.

   - Support for building the kernel to run as a "Secure Virtual
     Machine", ie. as a guest capable of running on a system with an
     Ultravisor.

   - Some changes to our DMA code on bare metal, to allow devices with
     medium sized DMA masks (&gt; 32 &amp;&amp; &lt; 59 bits) to use more than 2GB of
     DMA space.

   - Support for firmware assisted crash dumps on bare metal (powernv).

   - Two series fixing bugs in and refactoring our PCI EEH code.

   - A large series refactoring our exception entry code to use gas
     macros, both to make it more readable and also enable some future
     optimisations.

  As well as many cleanups and other minor features &amp; fixups.

  Thanks to: Adam Zerella, Alexey Kardashevskiy, Alistair Popple, Andrew
  Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Anshuman Khandual,
  Balbir Singh, Benjamin Herrenschmidt, Cédric Le Goater, Christophe
  JAILLET, Christophe Leroy, Christopher M. Riedl, Christoph Hellwig,
  Claudio Carvalho, Daniel Axtens, David Gibson, David Hildenbrand,
  Desnes A. Nunes do Rosario, Ganesh Goudar, Gautham R. Shenoy, Greg
  Kurz, Guerney Hunt, Gustavo Romero, Halil Pasic, Hari Bathini, Joakim
  Tjernlund, Jonathan Neuschafer, Jordan Niethe, Leonardo Bras, Lianbo
  Jiang, Madhavan Srinivasan, Mahesh Salgaonkar, Mahesh Salgaonkar,
  Masahiro Yamada, Maxiwell S. Garcia, Michael Anderson, Nathan
  Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Oliver
  O'Halloran, Qian Cai, Ram Pai, Ravi Bangoria, Reza Arbab, Ryan Grimm,
  Sam Bobroff, Santosh Sivaraj, Segher Boessenkool, Sukadev Bhattiprolu,
  Thiago Bauermann, Thiago Jung Bauermann, Thomas Gleixner, Tom
  Lendacky, Vasant Hegde"

* tag 'powerpc-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (264 commits)
  powerpc/mm/mce: Keep irqs disabled during lockless page table walk
  powerpc: Use ftrace_graph_ret_addr() when unwinding
  powerpc/ftrace: Enable HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
  ftrace: Look up the address of return_to_handler() using helpers
  powerpc: dump kernel log before carrying out fadump or kdump
  docs: powerpc: Add missing documentation reference
  powerpc/xmon: Fix output of XIVE IPI
  powerpc/xmon: Improve output of XIVE interrupts
  powerpc/mm/radix: remove useless kernel messages
  powerpc/fadump: support holes in kernel boot memory area
  powerpc/fadump: remove RMA_START and RMA_END macros
  powerpc/fadump: update documentation about option to release opalcore
  powerpc/fadump: consider f/w load area
  powerpc/opalcore: provide an option to invalidate /sys/firmware/opal/core file
  powerpc/opalcore: export /sys/firmware/opal/core for analysing opal crashes
  powerpc/fadump: update documentation about CONFIG_PRESERVE_FA_DUMP
  powerpc/fadump: add support to preserve crash data on FADUMP disabled kernel
  powerpc/fadump: improve how crashed kernel's memory is reserved
  powerpc/fadump: consider reserved ranges while releasing memory
  powerpc/fadump: make crash memory ranges array allocation generic
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull powerpc updates from Michael Ellerman:
 "This is a bit late, partly due to me travelling, and partly due to a
  power outage knocking out some of my test systems *while* I was
  travelling.

   - Initial support for running on a system with an Ultravisor, which
     is software that runs below the hypervisor and protects guests
     against some attacks by the hypervisor.

   - Support for building the kernel to run as a "Secure Virtual
     Machine", ie. as a guest capable of running on a system with an
     Ultravisor.

   - Some changes to our DMA code on bare metal, to allow devices with
     medium sized DMA masks (&gt; 32 &amp;&amp; &lt; 59 bits) to use more than 2GB of
     DMA space.

   - Support for firmware assisted crash dumps on bare metal (powernv).

   - Two series fixing bugs in and refactoring our PCI EEH code.

   - A large series refactoring our exception entry code to use gas
     macros, both to make it more readable and also enable some future
     optimisations.

  As well as many cleanups and other minor features &amp; fixups.

  Thanks to: Adam Zerella, Alexey Kardashevskiy, Alistair Popple, Andrew
  Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Anshuman Khandual,
  Balbir Singh, Benjamin Herrenschmidt, Cédric Le Goater, Christophe
  JAILLET, Christophe Leroy, Christopher M. Riedl, Christoph Hellwig,
  Claudio Carvalho, Daniel Axtens, David Gibson, David Hildenbrand,
  Desnes A. Nunes do Rosario, Ganesh Goudar, Gautham R. Shenoy, Greg
  Kurz, Guerney Hunt, Gustavo Romero, Halil Pasic, Hari Bathini, Joakim
  Tjernlund, Jonathan Neuschafer, Jordan Niethe, Leonardo Bras, Lianbo
  Jiang, Madhavan Srinivasan, Mahesh Salgaonkar, Mahesh Salgaonkar,
  Masahiro Yamada, Maxiwell S. Garcia, Michael Anderson, Nathan
  Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Oliver
  O'Halloran, Qian Cai, Ram Pai, Ravi Bangoria, Reza Arbab, Ryan Grimm,
  Sam Bobroff, Santosh Sivaraj, Segher Boessenkool, Sukadev Bhattiprolu,
  Thiago Bauermann, Thiago Jung Bauermann, Thomas Gleixner, Tom
  Lendacky, Vasant Hegde"

* tag 'powerpc-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (264 commits)
  powerpc/mm/mce: Keep irqs disabled during lockless page table walk
  powerpc: Use ftrace_graph_ret_addr() when unwinding
  powerpc/ftrace: Enable HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
  ftrace: Look up the address of return_to_handler() using helpers
  powerpc: dump kernel log before carrying out fadump or kdump
  docs: powerpc: Add missing documentation reference
  powerpc/xmon: Fix output of XIVE IPI
  powerpc/xmon: Improve output of XIVE interrupts
  powerpc/mm/radix: remove useless kernel messages
  powerpc/fadump: support holes in kernel boot memory area
  powerpc/fadump: remove RMA_START and RMA_END macros
  powerpc/fadump: update documentation about option to release opalcore
  powerpc/fadump: consider f/w load area
  powerpc/opalcore: provide an option to invalidate /sys/firmware/opal/core file
  powerpc/opalcore: export /sys/firmware/opal/core for analysing opal crashes
  powerpc/fadump: update documentation about CONFIG_PRESERVE_FA_DUMP
  powerpc/fadump: add support to preserve crash data on FADUMP disabled kernel
  powerpc/fadump: improve how crashed kernel's memory is reserved
  powerpc/fadump: consider reserved ranges while releasing memory
  powerpc/fadump: make crash memory ranges array allocation generic
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc: Use ftrace_graph_ret_addr() when unwinding</title>
<updated>2019-09-18T02:24:55+00:00</updated>
<author>
<name>Naveen N. Rao</name>
<email>naveen.n.rao@linux.vnet.ibm.com</email>
</author>
<published>2019-09-05T18:20:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7c1bb6bbf75d8ca5ec878627d3170effcaf54f27'/>
<id>7c1bb6bbf75d8ca5ec878627d3170effcaf54f27</id>
<content type='text'>
With support for HAVE_FUNCTION_GRAPH_RET_ADDR_PTR,
ftrace_graph_ret_addr() provides more robust unwinding when function
graph is in use. Update show_stack() to use the same.

With dump_stack() added to sysrq_sysctl_handler(), before this patch:
  root@(none):/sys/kernel/debug/tracing# cat /proc/sys/kernel/sysrq
  CPU: 0 PID: 218 Comm: cat Not tainted 5.3.0-rc7-00868-g8453ad4a078c-dirty #20
  Call Trace:
  [c0000000d1e13c30] [c00000000006ab98] return_to_handler+0x0/0x40 (dump_stack+0xe8/0x164) (unreliable)
  [c0000000d1e13c80] [c000000000145680] sysrq_sysctl_handler+0x48/0xb8
  [c0000000d1e13cd0] [c00000000006ab98] return_to_handler+0x0/0x40 (proc_sys_call_handler+0x274/0x2a0)
  [c0000000d1e13d60] [c00000000006ab98] return_to_handler+0x0/0x40 (return_to_handler+0x0/0x40)
  [c0000000d1e13d80] [c00000000006ab98] return_to_handler+0x0/0x40 (__vfs_read+0x3c/0x70)
  [c0000000d1e13dd0] [c00000000006ab98] return_to_handler+0x0/0x40 (vfs_read+0xb8/0x1b0)
  [c0000000d1e13e20] [c00000000006ab98] return_to_handler+0x0/0x40 (ksys_read+0x7c/0x140)

After this patch:
  Call Trace:
  [c0000000d1e33c30] [c00000000006ab58] return_to_handler+0x0/0x40 (dump_stack+0xe8/0x164) (unreliable)
  [c0000000d1e33c80] [c000000000145680] sysrq_sysctl_handler+0x48/0xb8
  [c0000000d1e33cd0] [c00000000006ab58] return_to_handler+0x0/0x40 (proc_sys_call_handler+0x274/0x2a0)
  [c0000000d1e33d60] [c00000000006ab58] return_to_handler+0x0/0x40 (__vfs_read+0x3c/0x70)
  [c0000000d1e33d80] [c00000000006ab58] return_to_handler+0x0/0x40 (vfs_read+0xb8/0x1b0)
  [c0000000d1e33dd0] [c00000000006ab58] return_to_handler+0x0/0x40 (ksys_read+0x7c/0x140)
  [c0000000d1e33e20] [c00000000006ab58] return_to_handler+0x0/0x40 (system_call+0x5c/0x68)

Signed-off-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/dc89c9a887121342d9c7819482c3dabdece2a323.1567707399.git.naveen.n.rao@linux.vnet.ibm.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
With support for HAVE_FUNCTION_GRAPH_RET_ADDR_PTR,
ftrace_graph_ret_addr() provides more robust unwinding when function
graph is in use. Update show_stack() to use the same.

With dump_stack() added to sysrq_sysctl_handler(), before this patch:
  root@(none):/sys/kernel/debug/tracing# cat /proc/sys/kernel/sysrq
  CPU: 0 PID: 218 Comm: cat Not tainted 5.3.0-rc7-00868-g8453ad4a078c-dirty #20
  Call Trace:
  [c0000000d1e13c30] [c00000000006ab98] return_to_handler+0x0/0x40 (dump_stack+0xe8/0x164) (unreliable)
  [c0000000d1e13c80] [c000000000145680] sysrq_sysctl_handler+0x48/0xb8
  [c0000000d1e13cd0] [c00000000006ab98] return_to_handler+0x0/0x40 (proc_sys_call_handler+0x274/0x2a0)
  [c0000000d1e13d60] [c00000000006ab98] return_to_handler+0x0/0x40 (return_to_handler+0x0/0x40)
  [c0000000d1e13d80] [c00000000006ab98] return_to_handler+0x0/0x40 (__vfs_read+0x3c/0x70)
  [c0000000d1e13dd0] [c00000000006ab98] return_to_handler+0x0/0x40 (vfs_read+0xb8/0x1b0)
  [c0000000d1e13e20] [c00000000006ab98] return_to_handler+0x0/0x40 (ksys_read+0x7c/0x140)

After this patch:
  Call Trace:
  [c0000000d1e33c30] [c00000000006ab58] return_to_handler+0x0/0x40 (dump_stack+0xe8/0x164) (unreliable)
  [c0000000d1e33c80] [c000000000145680] sysrq_sysctl_handler+0x48/0xb8
  [c0000000d1e33cd0] [c00000000006ab58] return_to_handler+0x0/0x40 (proc_sys_call_handler+0x274/0x2a0)
  [c0000000d1e33d60] [c00000000006ab58] return_to_handler+0x0/0x40 (__vfs_read+0x3c/0x70)
  [c0000000d1e33d80] [c00000000006ab58] return_to_handler+0x0/0x40 (vfs_read+0xb8/0x1b0)
  [c0000000d1e33dd0] [c00000000006ab58] return_to_handler+0x0/0x40 (ksys_read+0x7c/0x140)
  [c0000000d1e33e20] [c00000000006ab58] return_to_handler+0x0/0x40 (system_call+0x5c/0x68)

Signed-off-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/dc89c9a887121342d9c7819482c3dabdece2a323.1567707399.git.naveen.n.rao@linux.vnet.ibm.com
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/tm: Fix restoring FP/VMX facility incorrectly on interrupts</title>
<updated>2019-09-04T12:31:13+00:00</updated>
<author>
<name>Gustavo Romero</name>
<email>gromero@linux.ibm.com</email>
</author>
<published>2019-09-04T04:55:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a8318c13e79badb92bc6640704a64cc022a6eb97'/>
<id>a8318c13e79badb92bc6640704a64cc022a6eb97</id>
<content type='text'>
When in userspace and MSR FP=0 the hardware FP state is unrelated to
the current process. This is extended for transactions where if tbegin
is run with FP=0, the hardware checkpoint FP state will also be
unrelated to the current process. Due to this, we need to ensure this
hardware checkpoint is updated with the correct state before we enable
FP for this process.

Unfortunately we get this wrong when returning to a process from a
hardware interrupt. A process that starts a transaction with FP=0 can
take an interrupt. When the kernel returns back to that process, we
change to FP=1 but with hardware checkpoint FP state not updated. If
this transaction is then rolled back, the FP registers now contain the
wrong state.

The process looks like this:
   Userspace:                      Kernel

               Start userspace
                with MSR FP=0 TM=1
                  &lt; -----
   ...
   tbegin
   bne
               Hardware interrupt
                   ---- &gt;
                                    &lt;do_IRQ...&gt;
                                    ....
                                    ret_from_except
                                      restore_math()
				        /* sees FP=0 */
                                        restore_fp()
                                          tm_active_with_fp()
					    /* sees FP=1 (Incorrect) */
                                          load_fp_state()
                                        FP = 0 -&gt; 1
                  &lt; -----
               Return to userspace
                 with MSR TM=1 FP=1
                 with junk in the FP TM checkpoint
   TM rollback
   reads FP junk

When returning from the hardware exception, tm_active_with_fp() is
incorrectly making restore_fp() call load_fp_state() which is setting
FP=1.

The fix is to remove tm_active_with_fp().

tm_active_with_fp() is attempting to handle the case where FP state
has been changed inside a transaction. In this case the checkpointed
and transactional FP state is different and hence we must restore the
FP state (ie. we can't do lazy FP restore inside a transaction that's
used FP). It's safe to remove tm_active_with_fp() as this case is
handled by restore_tm_state(). restore_tm_state() detects if FP has
been using inside a transaction and will set load_fp and call
restore_math() to ensure the FP state (checkpoint and transaction) is
restored.

This is a data integrity problem for the current process as the FP
registers are corrupted. It's also a security problem as the FP
registers from one process may be leaked to another.

Similarly for VMX.

A simple testcase to replicate this will be posted to
tools/testing/selftests/powerpc/tm/tm-poison.c

This fixes CVE-2019-15031.

Fixes: a7771176b439 ("powerpc: Don't enable FP/Altivec if not checkpointed")
Cc: stable@vger.kernel.org # 4.15+
Signed-off-by: Gustavo Romero &lt;gromero@linux.ibm.com&gt;
Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190904045529.23002-2-gromero@linux.vnet.ibm.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When in userspace and MSR FP=0 the hardware FP state is unrelated to
the current process. This is extended for transactions where if tbegin
is run with FP=0, the hardware checkpoint FP state will also be
unrelated to the current process. Due to this, we need to ensure this
hardware checkpoint is updated with the correct state before we enable
FP for this process.

Unfortunately we get this wrong when returning to a process from a
hardware interrupt. A process that starts a transaction with FP=0 can
take an interrupt. When the kernel returns back to that process, we
change to FP=1 but with hardware checkpoint FP state not updated. If
this transaction is then rolled back, the FP registers now contain the
wrong state.

The process looks like this:
   Userspace:                      Kernel

               Start userspace
                with MSR FP=0 TM=1
                  &lt; -----
   ...
   tbegin
   bne
               Hardware interrupt
                   ---- &gt;
                                    &lt;do_IRQ...&gt;
                                    ....
                                    ret_from_except
                                      restore_math()
				        /* sees FP=0 */
                                        restore_fp()
                                          tm_active_with_fp()
					    /* sees FP=1 (Incorrect) */
                                          load_fp_state()
                                        FP = 0 -&gt; 1
                  &lt; -----
               Return to userspace
                 with MSR TM=1 FP=1
                 with junk in the FP TM checkpoint
   TM rollback
   reads FP junk

When returning from the hardware exception, tm_active_with_fp() is
incorrectly making restore_fp() call load_fp_state() which is setting
FP=1.

The fix is to remove tm_active_with_fp().

tm_active_with_fp() is attempting to handle the case where FP state
has been changed inside a transaction. In this case the checkpointed
and transactional FP state is different and hence we must restore the
FP state (ie. we can't do lazy FP restore inside a transaction that's
used FP). It's safe to remove tm_active_with_fp() as this case is
handled by restore_tm_state(). restore_tm_state() detects if FP has
been using inside a transaction and will set load_fp and call
restore_math() to ensure the FP state (checkpoint and transaction) is
restored.

This is a data integrity problem for the current process as the FP
registers are corrupted. It's also a security problem as the FP
registers from one process may be leaked to another.

Similarly for VMX.

A simple testcase to replicate this will be posted to
tools/testing/selftests/powerpc/tm/tm-poison.c

This fixes CVE-2019-15031.

Fixes: a7771176b439 ("powerpc: Don't enable FP/Altivec if not checkpointed")
Cc: stable@vger.kernel.org # 4.15+
Signed-off-by: Gustavo Romero &lt;gromero@linux.ibm.com&gt;
Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190904045529.23002-2-gromero@linux.vnet.ibm.com
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/tm: Fix FP/VMX unavailable exceptions inside a transaction</title>
<updated>2019-09-04T12:31:13+00:00</updated>
<author>
<name>Gustavo Romero</name>
<email>gromero@linux.ibm.com</email>
</author>
<published>2019-09-04T04:55:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8205d5d98ef7f155de211f5e2eb6ca03d95a5a60'/>
<id>8205d5d98ef7f155de211f5e2eb6ca03d95a5a60</id>
<content type='text'>
When we take an FP unavailable exception in a transaction we have to
account for the hardware FP TM checkpointed registers being
incorrect. In this case for this process we know the current and
checkpointed FP registers must be the same (since FP wasn't used
inside the transaction) hence in the thread_struct we copy the current
FP registers to the checkpointed ones.

This copy is done in tm_reclaim_thread(). We use thread-&gt;ckpt_regs.msr
to determine if FP was on when in userspace. thread-&gt;ckpt_regs.msr
represents the state of the MSR when exiting userspace. This is setup
by check_if_tm_restore_required().

Unfortunatley there is an optimisation in giveup_all() which returns
early if tsk-&gt;thread.regs-&gt;msr (via local variable `usermsr`) has
FP=VEC=VSX=SPE=0. This optimisation means that
check_if_tm_restore_required() is not called and hence
thread-&gt;ckpt_regs.msr is not updated and will contain an old value.

This can happen if due to load_fp=255 we start a userspace process
with MSR FP=1 and then we are context switched out. In this case
thread-&gt;ckpt_regs.msr will contain FP=1. If that same process is then
context switched in and load_fp overflows, MSR will have FP=0. If that
process now enters a transaction and does an FP instruction, the FP
unavailable will not update thread-&gt;ckpt_regs.msr (the bug) and MSR
FP=1 will be retained in thread-&gt;ckpt_regs.msr.  tm_reclaim_thread()
will then not perform the required memcpy and the checkpointed FP regs
in the thread struct will contain the wrong values.

The code path for this happening is:

       Userspace:                      Kernel
                   Start userspace
                    with MSR FP/VEC/VSX/SPE=0 TM=1
                      &lt; -----
       ...
       tbegin
       bne
       fp instruction
                   FP unavailable
                       ---- &gt;
                                        fp_unavailable_tm()
					  tm_reclaim_current()
					    tm_reclaim_thread()
					      giveup_all()
					        return early since FP/VMX/VSX=0
						/* ckpt MSR not updated (Incorrect) */
					      tm_reclaim()
					        /* thread_struct ckpt FP regs contain junk (OK) */
                                              /* Sees ckpt MSR FP=1 (Incorrect) */
					      no memcpy() performed
					        /* thread_struct ckpt FP regs not fixed (Incorrect) */
					  tm_recheckpoint()
					     /* Put junk in hardware checkpoint FP regs */
                                         ....
                      &lt; -----
                   Return to userspace
                     with MSR TM=1 FP=1
                     with junk in the FP TM checkpoint
       TM rollback
       reads FP junk

This is a data integrity problem for the current process as the FP
registers are corrupted. It's also a security problem as the FP
registers from one process may be leaked to another.

This patch moves up check_if_tm_restore_required() in giveup_all() to
ensure thread-&gt;ckpt_regs.msr is updated correctly.

A simple testcase to replicate this will be posted to
tools/testing/selftests/powerpc/tm/tm-poison.c

Similarly for VMX.

This fixes CVE-2019-15030.

Fixes: f48e91e87e67 ("powerpc/tm: Fix FP and VMX register corruption")
Cc: stable@vger.kernel.org # 4.12+
Signed-off-by: Gustavo Romero &lt;gromero@linux.vnet.ibm.com&gt;
Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190904045529.23002-1-gromero@linux.vnet.ibm.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When we take an FP unavailable exception in a transaction we have to
account for the hardware FP TM checkpointed registers being
incorrect. In this case for this process we know the current and
checkpointed FP registers must be the same (since FP wasn't used
inside the transaction) hence in the thread_struct we copy the current
FP registers to the checkpointed ones.

This copy is done in tm_reclaim_thread(). We use thread-&gt;ckpt_regs.msr
to determine if FP was on when in userspace. thread-&gt;ckpt_regs.msr
represents the state of the MSR when exiting userspace. This is setup
by check_if_tm_restore_required().

Unfortunatley there is an optimisation in giveup_all() which returns
early if tsk-&gt;thread.regs-&gt;msr (via local variable `usermsr`) has
FP=VEC=VSX=SPE=0. This optimisation means that
check_if_tm_restore_required() is not called and hence
thread-&gt;ckpt_regs.msr is not updated and will contain an old value.

This can happen if due to load_fp=255 we start a userspace process
with MSR FP=1 and then we are context switched out. In this case
thread-&gt;ckpt_regs.msr will contain FP=1. If that same process is then
context switched in and load_fp overflows, MSR will have FP=0. If that
process now enters a transaction and does an FP instruction, the FP
unavailable will not update thread-&gt;ckpt_regs.msr (the bug) and MSR
FP=1 will be retained in thread-&gt;ckpt_regs.msr.  tm_reclaim_thread()
will then not perform the required memcpy and the checkpointed FP regs
in the thread struct will contain the wrong values.

The code path for this happening is:

       Userspace:                      Kernel
                   Start userspace
                    with MSR FP/VEC/VSX/SPE=0 TM=1
                      &lt; -----
       ...
       tbegin
       bne
       fp instruction
                   FP unavailable
                       ---- &gt;
                                        fp_unavailable_tm()
					  tm_reclaim_current()
					    tm_reclaim_thread()
					      giveup_all()
					        return early since FP/VMX/VSX=0
						/* ckpt MSR not updated (Incorrect) */
					      tm_reclaim()
					        /* thread_struct ckpt FP regs contain junk (OK) */
                                              /* Sees ckpt MSR FP=1 (Incorrect) */
					      no memcpy() performed
					        /* thread_struct ckpt FP regs not fixed (Incorrect) */
					  tm_recheckpoint()
					     /* Put junk in hardware checkpoint FP regs */
                                         ....
                      &lt; -----
                   Return to userspace
                     with MSR TM=1 FP=1
                     with junk in the FP TM checkpoint
       TM rollback
       reads FP junk

This is a data integrity problem for the current process as the FP
registers are corrupted. It's also a security problem as the FP
registers from one process may be leaked to another.

This patch moves up check_if_tm_restore_required() in giveup_all() to
ensure thread-&gt;ckpt_regs.msr is updated correctly.

A simple testcase to replicate this will be posted to
tools/testing/selftests/powerpc/tm/tm-poison.c

Similarly for VMX.

This fixes CVE-2019-15030.

Fixes: f48e91e87e67 ("powerpc/tm: Fix FP and VMX register corruption")
Cc: stable@vger.kernel.org # 4.12+
Signed-off-by: Gustavo Romero &lt;gromero@linux.vnet.ibm.com&gt;
Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190904045529.23002-1-gromero@linux.vnet.ibm.com
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc: convert to copy_thread_tls</title>
<updated>2019-08-28T13:19:34+00:00</updated>
<author>
<name>Nicholas Piggin</name>
<email>npiggin@gmail.com</email>
</author>
<published>2019-08-27T03:30:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=facd04a904ff6cdc6ee85d6e85d500f478a1bec4'/>
<id>facd04a904ff6cdc6ee85d6e85d500f478a1bec4</id>
<content type='text'>
Commit 3033f14ab78c3 ("clone: support passing tls argument via C rather
than pt_regs magic") introduced the HAVE_COPY_THREAD_TLS option. Use it
to avoid a subtle assumption about the argument ordering of clone type
syscalls.

Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190827033010.28090-2-npiggin@gmail.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit 3033f14ab78c3 ("clone: support passing tls argument via C rather
than pt_regs magic") introduced the HAVE_COPY_THREAD_TLS option. Use it
to avoid a subtle assumption about the argument ordering of clone type
syscalls.

Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190827033010.28090-2-npiggin@gmail.com
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux</title>
<updated>2019-07-13T23:08:36+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-07-13T23:08:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=192f0f8e9db7efe4ac98d47f5fa4334e43c1204d'/>
<id>192f0f8e9db7efe4ac98d47f5fa4334e43c1204d</id>
<content type='text'>
Pull powerpc updates from Michael Ellerman:
 "Notable changes:

   - Removal of the NPU DMA code, used by the out-of-tree Nvidia driver,
     as well as some other functions only used by drivers that haven't
     (yet?) made it upstream.

   - A fix for a bug in our handling of hardware watchpoints (eg. perf
     record -e mem: ...) which could lead to register corruption and
     kernel crashes.

   - Enable HAVE_ARCH_HUGE_VMAP, which allows us to use large pages for
     vmalloc when using the Radix MMU.

   - A large but incremental rewrite of our exception handling code to
     use gas macros rather than multiple levels of nested CPP macros.

  And the usual small fixes, cleanups and improvements.

  Thanks to: Alastair D'Silva, Alexey Kardashevskiy, Andreas Schwab,
  Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann,
  Athira Rajeev, Cédric Le Goater, Christian Lamparter, Christophe
  Leroy, Christophe Lombard, Christoph Hellwig, Daniel Axtens, Denis
  Efremov, Enrico Weigelt, Frederic Barrat, Gautham R. Shenoy, Geert
  Uytterhoeven, Geliang Tang, Gen Zhang, Greg Kroah-Hartman, Greg Kurz,
  Gustavo Romero, Krzysztof Kozlowski, Madhavan Srinivasan, Masahiro
  Yamada, Mathieu Malaterre, Michael Neuling, Nathan Lynch, Naveen N.
  Rao, Nicholas Piggin, Nishad Kamdar, Oliver O'Halloran, Qian Cai, Ravi
  Bangoria, Sachin Sant, Sam Bobroff, Satheesh Rajendran, Segher
  Boessenkool, Shaokun Zhang, Shawn Anastasio, Stewart Smith, Suraj
  Jitindar Singh, Thiago Jung Bauermann, YueHaibing"

* tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (163 commits)
  powerpc/powernv/idle: Fix restore of SPRN_LDBAR for POWER9 stop state.
  powerpc/eeh: Handle hugepages in ioremap space
  ocxl: Update for AFU descriptor template version 1.1
  powerpc/boot: pass CONFIG options in a simpler and more robust way
  powerpc/boot: add {get, put}_unaligned_be32 to xz_config.h
  powerpc/irq: Don't WARN continuously in arch_local_irq_restore()
  powerpc/module64: Use symbolic instructions names.
  powerpc/module32: Use symbolic instructions names.
  powerpc: Move PPC_HA() PPC_HI() and PPC_LO() to ppc-opcode.h
  powerpc/module64: Fix comment in R_PPC64_ENTRY handling
  powerpc/boot: Add lzo support for uImage
  powerpc/boot: Add lzma support for uImage
  powerpc/boot: don't force gzipped uImage
  powerpc/8xx: Add microcode patch to move SMC parameter RAM.
  powerpc/8xx: Use IO accessors in microcode programming.
  powerpc/8xx: replace #ifdefs by IS_ENABLED() in microcode.c
  powerpc/8xx: refactor programming of microcode CPM params.
  powerpc/8xx: refactor printing of microcode patch name.
  powerpc/8xx: Refactor microcode write
  powerpc/8xx: refactor writing of CPM microcode arrays
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull powerpc updates from Michael Ellerman:
 "Notable changes:

   - Removal of the NPU DMA code, used by the out-of-tree Nvidia driver,
     as well as some other functions only used by drivers that haven't
     (yet?) made it upstream.

   - A fix for a bug in our handling of hardware watchpoints (eg. perf
     record -e mem: ...) which could lead to register corruption and
     kernel crashes.

   - Enable HAVE_ARCH_HUGE_VMAP, which allows us to use large pages for
     vmalloc when using the Radix MMU.

   - A large but incremental rewrite of our exception handling code to
     use gas macros rather than multiple levels of nested CPP macros.

  And the usual small fixes, cleanups and improvements.

  Thanks to: Alastair D'Silva, Alexey Kardashevskiy, Andreas Schwab,
  Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann,
  Athira Rajeev, Cédric Le Goater, Christian Lamparter, Christophe
  Leroy, Christophe Lombard, Christoph Hellwig, Daniel Axtens, Denis
  Efremov, Enrico Weigelt, Frederic Barrat, Gautham R. Shenoy, Geert
  Uytterhoeven, Geliang Tang, Gen Zhang, Greg Kroah-Hartman, Greg Kurz,
  Gustavo Romero, Krzysztof Kozlowski, Madhavan Srinivasan, Masahiro
  Yamada, Mathieu Malaterre, Michael Neuling, Nathan Lynch, Naveen N.
  Rao, Nicholas Piggin, Nishad Kamdar, Oliver O'Halloran, Qian Cai, Ravi
  Bangoria, Sachin Sant, Sam Bobroff, Satheesh Rajendran, Segher
  Boessenkool, Shaokun Zhang, Shawn Anastasio, Stewart Smith, Suraj
  Jitindar Singh, Thiago Jung Bauermann, YueHaibing"

* tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (163 commits)
  powerpc/powernv/idle: Fix restore of SPRN_LDBAR for POWER9 stop state.
  powerpc/eeh: Handle hugepages in ioremap space
  ocxl: Update for AFU descriptor template version 1.1
  powerpc/boot: pass CONFIG options in a simpler and more robust way
  powerpc/boot: add {get, put}_unaligned_be32 to xz_config.h
  powerpc/irq: Don't WARN continuously in arch_local_irq_restore()
  powerpc/module64: Use symbolic instructions names.
  powerpc/module32: Use symbolic instructions names.
  powerpc: Move PPC_HA() PPC_HI() and PPC_LO() to ppc-opcode.h
  powerpc/module64: Fix comment in R_PPC64_ENTRY handling
  powerpc/boot: Add lzo support for uImage
  powerpc/boot: Add lzma support for uImage
  powerpc/boot: don't force gzipped uImage
  powerpc/8xx: Add microcode patch to move SMC parameter RAM.
  powerpc/8xx: Use IO accessors in microcode programming.
  powerpc/8xx: replace #ifdefs by IS_ENABLED() in microcode.c
  powerpc/8xx: refactor programming of microcode CPM params.
  powerpc/8xx: refactor printing of microcode patch name.
  powerpc/8xx: Refactor microcode write
  powerpc/8xx: refactor writing of CPM microcode arrays
  ...
</pre>
</div>
</content>
</entry>
</feed>
