linux-stable.git/arch/powerpc/kernel, branch linux-6.3.y

powerpc: update ppc_save_regs to save current r1 in pt_regs

2023-07-11T17:39:48+00:00

[ Upstream commit b684c09f09e7a6af3794d4233ef785819e72db79 ]

ppc_save_regs() skips one stack frame while saving the CPU register states.
Instead of saving current R1, it pulls the previous stack frame pointer.

When vmcores caused by direct panic call (such as `echo c >
/proc/sysrq-trigger`), are debugged with gdb, gdb fails to show the
backtrace correctly. On further analysis, it was found that it was because
of mismatch between r1 and NIP.

GDB uses NIP to get current function symbol and uses corresponding debug
info of that function to unwind previous frames, but due to the
mismatching r1 and NIP, the unwinding does not work, and it fails to
unwind to the 2nd frame and hence does not show the backtrace.

GDB backtrace with vmcore of kernel without this patch:

---------
(gdb) bt
 #0  0xc0000000002a53e8 in crash_setup_regs (oldregs=,
    newregs=0xc000000004f8f8d8) at ./arch/powerpc/include/asm/kexec.h:69
 #1  __crash_kexec (regs=) at kernel/kexec_core.c:974
 #2  0x0000000000000063 in ?? ()
 #3  0xc000000003579320 in ?? ()
---------

Further analysis revealed that the mismatch occurred because
"ppc_save_regs" was saving the previous stack's SP instead of the current
r1. This patch fixes this by storing current r1 in the saved pt_regs.

GDB backtrace with vmcore of patched kernel:

--------
(gdb) bt
 #0  0xc0000000002a53e8 in crash_setup_regs (oldregs=0x0, newregs=0xc00000000670b8d8)
    at ./arch/powerpc/include/asm/kexec.h:69
 #1  __crash_kexec (regs=regs@entry=0x0) at kernel/kexec_core.c:974
 #2  0xc000000000168918 in panic (fmt=fmt@entry=0xc000000001654a60 "sysrq triggered crash\n")
    at kernel/panic.c:358
 #3  0xc000000000b735f8 in sysrq_handle_crash (key=) at drivers/tty/sysrq.c:155
 #4  0xc000000000b742cc in __handle_sysrq (key=key@entry=99, check_mask=check_mask@entry=false)
    at drivers/tty/sysrq.c:602
 #5  0xc000000000b7506c in write_sysrq_trigger (file=, buf=,
    count=2, ppos=) at drivers/tty/sysrq.c:1163
 #6  0xc00000000069a7bc in pde_write (ppos=, count=,
    buf=, file=, pde=0xc00000000362cb40) at fs/proc/inode.c:340
 #7  proc_reg_write (file=, buf=, count=,
    ppos=) at fs/proc/inode.c:352
 #8  0xc0000000005b3bbc in vfs_write (file=file@entry=0xc000000006aa6b00,
    buf=buf@entry=0x61f498b4f60 ,
    count=count@entry=2, pos=pos@entry=0xc00000000670bda0) at fs/read_write.c:582
 #9  0xc0000000005b4264 in ksys_write (fd=,
    buf=0x61f498b4f60 , count=2)
    at fs/read_write.c:637
 #10 0xc00000000002ea2c in system_call_exception (regs=0xc00000000670be80, r0=)
    at arch/powerpc/kernel/syscall.c:171
 #11 0xc00000000000c270 in system_call_vectored_common ()
    at arch/powerpc/kernel/interrupt_64.S:192
--------

Nick adds:
  So this now saves regs as though it was an interrupt taken in the
  caller, at the instruction after the call to ppc_save_regs, whereas
  previously the NIP was there, but R1 came from the caller's caller and
  that mismatch is what causes gdb's dwarf unwinder to go haywire.

Signed-off-by: Aditya Gupta 
Fixes: d16a58f8854b1 ("powerpc: Improve ppc_save_regs()")
Reivewed-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230615091047.90433-1-adityag@linux.ibm.com
Signed-off-by: Sasha Levin

powerpc/signal32: Force inlining of __unsafe_save_user_regs() and save_tm_user_regs_unsafe()

2023-07-11T17:39:47+00:00

[ Upstream commit a03b1a0b19398a47489fdcef02ec19c2ba05a15d ]

Looking at generated code for handle_signal32() shows calls to a
function called __unsafe_save_user_regs.constprop.0 while user access
is open.

And that __unsafe_save_user_regs.constprop.0 function has two nops at
the begining, allowing it to be traced, which is unexpected during
user access open window.

The solution could be to mark __unsafe_save_user_regs() no trace, but
to be on the safe side the most efficient is to flag it __always_inline
as already done for function __unsafe_restore_general_regs(). The
function is relatively small and only called twice, so the size
increase will remain in the noise.

Do the same with save_tm_user_regs_unsafe() as it may suffer the
same issue.

Fixes: ef75e7318294 ("powerpc/signal32: Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version")
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/7e469c8f01860a69c1ada3ca6a5e2aa65f0f74b2.1685955220.git.christophe.leroy@csgroup.eu
Signed-off-by: Sasha Levin

powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare()

2023-07-11T17:39:47+00:00

[ Upstream commit 0eb089a72fda3f7969e6277804bde75dc1474a14 ]

A disassembly of interrupt_exit_kernel_prepare() shows a useless read
of MSR register. This is shown by r9 being re-used immediately without
doing anything with the value read.

  c000e0e0:       60 00 00 00     nop
  c000e0e4:       7d 3a c2 a6     mfmd_ap r9
  c000e0e8:       7d 20 00 a6     mfmsr   r9
  c000e0ec:       7c 51 13 a6     mtspr   81,r2
  c000e0f0:       81 3f 00 84     lwz     r9,132(r31)
  c000e0f4:       71 29 80 00     andi.   r9,r9,32768

This is due to the use of local_irq_save(). The flags read by
local_irq_save() are never used, use local_irq_disable() instead.

Fixes: 13799748b957 ("powerpc/64: use interrupt restart table to speed up return from interrupt")
Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/df36c6205ab64326fb1b991993c82057e92ace2f.1685955214.git.christophe.leroy@csgroup.eu
Signed-off-by: Sasha Levin

powerpc/iommu: Incorrect DDW Table is referenced for SR-IOV device

2023-05-24T16:30:23+00:00

commit 1f7aacc5eb9ed2cc17be7a90da5cd559effb9d59 upstream.

For an SR-IOV device, while enabling DDW, a new table is created and
added at index 1 in the group. In the below 2 scenarios, the table is
incorrectly referenced at index 0 (which is where the table is for
default DMA window).

1. When adding DDW

   This issue is exposed with "slub_debug". Error thrown out from
   dma_iommu_dma_supported()

   Warning: IOMMU offset too big for device mask
   mask: 0xffffffff, table offset: 0x800000000000000

2. During Dynamic removal of the PCI device.

   Error is from iommu_tce_table_put() since a NULL table pointer is
   passed in.

Fixes: 381ceda88c4c ("powerpc/pseries/iommu: Make use of DDW for indirect mapping")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Gaurav Batra 
Reviewed-by: Brian King 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230505184701.91613-1-gbatra@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman

powerpc/iommu: DMA address offset is incorrectly calculated with 2MB TCEs

2023-05-24T16:30:23+00:00

commit 096339ab84f36beae0b1db25e0ce63fb3873e8b2 upstream.

When DMA window is backed by 2MB TCEs, the DMA address for the mapped
page should be the offset of the page relative to the 2MB TCE. The code
was incorrectly setting the DMA address to the beginning of the TCE
range.

Mellanox driver is reporting timeout trying to ENABLE_HCA for an SR-IOV
ethernet port, when DMA window is backed by 2MB TCEs.

Fixes: 387273118714 ("powerps/pseries/dma: Add support for 2M IOMMU page size")
Cc: stable@vger.kernel.org # v5.16+
Signed-off-by: Gaurav Batra 
Reviewed-by: Greg Joyce 
Reviewed-by: Brian King 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230504175913.83844-1-gbatra@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman

powerpc: Use of_property_present() for testing DT property presence

2023-05-24T16:30:10+00:00

[ Upstream commit 857d423c74228cfa064f79ff3a16b163fdb8d542 ]

It is preferred to use typed property access functions (i.e.
of_property_read_ functions) rather than low-level
of_get_property/of_find_property functions for reading properties. As
part of this, convert of_get_property/of_find_property calls to the
recently added of_property_present() helper when we just want to test
for presence of a property and nothing more.

Signed-off-by: Rob Herring 
[mpe: Drop change in ppc4xx_probe_pci_bridge(), formatting]
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230310144657.1541039-1-robh@kernel.org
Signed-off-by: Sasha Levin

powerpc/rtas: use memmove for potentially overlapping buffer copy

2023-05-11T14:17:29+00:00

[ Upstream commit 271208ee5e335cb1ad280d22784940daf7ddf820 ]

Using memcpy() isn't safe when buf is identical to rtas_err_buf, which
can happen during boot before slab is up. Full context which may not
be obvious from the diff:

	if (altbuf) {
		buf = altbuf;
	} else {
		buf = rtas_err_buf;
		if (slab_is_available())
			buf = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
	}
	if (buf)
		memcpy(buf, rtas_err_buf, RTAS_ERROR_LOG_MAX);

This was found by inspection and I'm not aware of it causing problems
in practice. It appears to have been introduced by commit
033ef338b6e0 ("powerpc: Merge rtas.c into arch/powerpc/kernel"); the
old ppc64 version of this code did not have this problem.

Use memmove() instead.

Fixes: 033ef338b6e0 ("powerpc: Merge rtas.c into arch/powerpc/kernel")
Signed-off-by: Nathan Lynch 
Reviewed-by: Andrew Donnellan 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230220-rtas-queue-for-6-4-v1-2-010e4416f13f@linux.ibm.com
Signed-off-by: Sasha Levin

Merge tag 'powerpc-6.3-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2023-04-02T17:01:56+00:00

Pull powerpc fixes from Michael Ellerman:

 - Fix a false positive warning in __pte_needs_flush() (with DEBUG_VM=y)

 - Fix oops when a PF_IO_WORKER thread tries to core dump

 - Don't try to reconfigure VAS when it's disabled

Thanks to Benjamin Gray, Haren Myneni, Jens Axboe, Nathan Lynch, and
Russell Currey.

* tag 'powerpc-6.3-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled
  powerpc: Don't try to copy PPR for task with NULL pt_regs
  powerpc/64s: Fix __pte_needs_flush() false positive warning

powerpc: Don't try to copy PPR for task with NULL pt_regs

2023-03-28T11:11:41+00:00

powerpc sets up PF_KTHREAD and PF_IO_WORKER with a NULL pt_regs, which
from my (arguably very short) checking is not commonly done for other
archs. This is fine, except when PF_IO_WORKER's have been created and
the task does something that causes a coredump to be generated. Then we
get this crash:

  Kernel attempted to read user page (160) - exploit attempt? (uid: 1000)
  BUG: Kernel NULL pointer dereference on read at 0x00000160
  Faulting instruction address: 0xc0000000000c3a60
  Oops: Kernel access of bad area, sig: 11 [#1]
  LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=32 NUMA pSeries
  Modules linked in: bochs drm_vram_helper drm_kms_helper xts binfmt_misc ecb ctr syscopyarea sysfillrect cbc sysimgblt drm_ttm_helper aes_generic ttm sg libaes evdev joydev virtio_balloon vmx_crypto gf128mul drm dm_mod fuse loop configfs drm_panel_orientation_quirks ip_tables x_tables autofs4 hid_generic usbhid hid xhci_pci xhci_hcd usbcore usb_common sd_mod
  CPU: 1 PID: 1982 Comm: ppc-crash Not tainted 6.3.0-rc2+ #88
  Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries
  NIP:  c0000000000c3a60 LR: c000000000039944 CTR: c0000000000398e0
  REGS: c0000000041833b0 TRAP: 0300   Not tainted  (6.3.0-rc2+)
  MSR:  800000000280b033   CR: 88082828  XER: 200400f8
  ...
  NIP memcpy_power7+0x200/0x7d0
  LR  ppr_get+0x64/0xb0
  Call Trace:
    ppr_get+0x40/0xb0 (unreliable)
    __regset_get+0x180/0x1f0
    regset_get_alloc+0x64/0x90
    elf_core_dump+0xb98/0x1b60
    do_coredump+0x1c34/0x24a0
    get_signal+0x71c/0x1410
    do_notify_resume+0x140/0x6f0
    interrupt_exit_user_prepare_main+0x29c/0x320
    interrupt_exit_user_prepare+0x6c/0xa0
    interrupt_return_srr_user+0x8/0x138

Because ppr_get() is trying to copy from a PF_IO_WORKER with a NULL
pt_regs.

Check for a valid pt_regs in both ppc_get/ppr_set, and return an error
if not set. The actual error value doesn't seem to be important here, so
just pick -EINVAL.

Fixes: fa439810cc1b ("powerpc/ptrace: Enable support for NT_PPPC_TAR, NT_PPC_PPR, NT_PPC_DSCR")
Cc: stable@vger.kernel.org # v4.8+
Signed-off-by: Jens Axboe 
[mpe: Trim oops in change log, add Fixes & Cc stable]
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/d9f63344-fe7c-56ae-b420-4a1a04a2ae4c@kernel.dk

kasan, powerpc: don't rename memintrinsics if compiler adds prefixes

2023-03-24T00:18:33+00:00

With appropriate compiler support [1], KASAN builds use __asan prefixed
meminstrinsics, and KASAN no longer overrides memcpy/memset/memmove.

If compiler support is detected (CC_HAS_KASAN_MEMINTRINSIC_PREFIX), define
memintrinsics normally (do not prefix '__').

On powerpc, KASAN is the only user of __mem functions, which are used to
define instrumented memintrinsics.  Alias the normal versions for KASAN to
use in its implementation.

Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/ [1]
Link: https://lore.kernel.org/oe-kbuild-all/202302271348.U5lvmo0S-lkp@intel.com/
Link: https://lkml.kernel.org/r/20230227094726.3833247-1-elver@google.com
Signed-off-by: Marco Elver 
Reported-by: kernel test robot 
Acked-by: Michael Ellerman 	[powerpc]
Cc: Alexander Potapenko 
Cc: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Christophe Leroy 
Cc: Daniel Axtens 
Cc: Dmitry Vyukov 
Cc: Liam R. Howlett 
Cc: Nicholas Piggin 
Cc: Vincenzo Frascino 
Signed-off-by: Andrew Morton