<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch, branch v6.1-rc2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2022-10-23T22:00:43+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-10-23T22:00:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=05b4ebd2c7cbb3671c376754b37b4963dd08a3a2'/>
<id>05b4ebd2c7cbb3671c376754b37b4963dd08a3a2</id>
<content type='text'>
Pull kvm fixes from Paolo Bonzini:
 "RISC-V:

   - Fix compilation without RISCV_ISA_ZICBOM

   - Fix kvm_riscv_vcpu_timer_pending() for Sstc

  ARM:

   - Fix a bug preventing restoring an ITS containing mappings for very
     large and very sparse device topology

   - Work around a relocation handling error when compiling the nVHE
     object with profile optimisation

   - Fix for stage-2 invalidation holding the VM MMU lock for too long
     by limiting the walk to the largest block mapping size

   - Enable stack protection and branch profiling for VHE

   - Two selftest fixes

  x86:

   - add compat implementation for KVM_X86_SET_MSR_FILTER ioctl

  selftests:

   - synchronize includes between include/uapi and tools/include/uapi"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  tools: include: sync include/api/linux/kvm.h
  KVM: x86: Add compat handler for KVM_X86_SET_MSR_FILTER
  KVM: x86: Copy filter arg outside kvm_vm_ioctl_set_msr_filter()
  kvm: Add support for arch compat vm ioctls
  RISC-V: KVM: Fix kvm_riscv_vcpu_timer_pending() for Sstc
  RISC-V: Fix compilation without RISCV_ISA_ZICBOM
  KVM: arm64: vgic: Fix exit condition in scan_its_table()
  KVM: arm64: nvhe: Fix build with profile optimization
  KVM: selftests: Fix number of pages for memory slot in memslot_modification_stress_test
  KVM: arm64: selftests: Fix multiple versions of GIC creation
  KVM: arm64: Enable stack protection and branch profiling for VHE
  KVM: arm64: Limit stage2_apply_range() batch size to largest block
  KVM: arm64: Work out supported block level at compile time
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull kvm fixes from Paolo Bonzini:
 "RISC-V:

   - Fix compilation without RISCV_ISA_ZICBOM

   - Fix kvm_riscv_vcpu_timer_pending() for Sstc

  ARM:

   - Fix a bug preventing restoring an ITS containing mappings for very
     large and very sparse device topology

   - Work around a relocation handling error when compiling the nVHE
     object with profile optimisation

   - Fix for stage-2 invalidation holding the VM MMU lock for too long
     by limiting the walk to the largest block mapping size

   - Enable stack protection and branch profiling for VHE

   - Two selftest fixes

  x86:

   - add compat implementation for KVM_X86_SET_MSR_FILTER ioctl

  selftests:

   - synchronize includes between include/uapi and tools/include/uapi"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  tools: include: sync include/api/linux/kvm.h
  KVM: x86: Add compat handler for KVM_X86_SET_MSR_FILTER
  KVM: x86: Copy filter arg outside kvm_vm_ioctl_set_msr_filter()
  kvm: Add support for arch compat vm ioctls
  RISC-V: KVM: Fix kvm_riscv_vcpu_timer_pending() for Sstc
  RISC-V: Fix compilation without RISCV_ISA_ZICBOM
  KVM: arm64: vgic: Fix exit condition in scan_its_table()
  KVM: arm64: nvhe: Fix build with profile optimization
  KVM: selftests: Fix number of pages for memory slot in memslot_modification_stress_test
  KVM: arm64: selftests: Fix multiple versions of GIC creation
  KVM: arm64: Enable stack protection and branch profiling for VHE
  KVM: arm64: Limit stage2_apply_range() batch size to largest block
  KVM: arm64: Work out supported block level at compile time
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'objtool_urgent_for_v6.1_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2022-10-23T17:07:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-10-23T17:07:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6204a81aa3f489e4fb43288d95d27c069bad4e1e'/>
<id>6204a81aa3f489e4fb43288d95d27c069bad4e1e</id>
<content type='text'>
Pull objtool fix from Borislav Petkov:

 - Fix ORC stack unwinding when GCOV is enabled

* tag 'objtool_urgent_for_v6.1_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/unwind/orc: Fix unreliable stack dump with gcov
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull objtool fix from Borislav Petkov:

 - Fix ORC stack unwinding when GCOV is enabled

* tag 'objtool_urgent_for_v6.1_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/unwind/orc: Fix unreliable stack dump with gcov
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'x86_urgent_for_v6.0_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2022-10-23T17:01:34+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-10-23T17:01:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=295dad10bfb5bc35ef0d051aec61299ebeb88855'/>
<id>295dad10bfb5bc35ef0d051aec61299ebeb88855</id>
<content type='text'>
Pull x86 fixes from Borislav Petkov:
 "As usually the case, right after a major release, the tip urgent
  branches accumulate a couple more fixes than normal. And here is the
  x86, a bit bigger, urgent pile.

   - Use the correct CPU capability clearing function on the error path
     in Intel perf LBR

   - A CFI fix to ftrace along with a simplification

   - Adjust handling of zero capacity bit mask for resctrl cache
     allocation on AMD

   - A fix to the AMD microcode loader to attempt patch application on
     every logical thread

   - A couple of topology fixes to handle CPUID leaf 0x1f enumeration
     info properly

   - Drop a -mabi=ms compiler option check as both compilers support it
     now anyway

   - A couple of fixes to how the initial, statically allocated FPU
     buffer state is setup and its interaction with dynamic states at
     runtime"

* tag 'x86_urgent_for_v6.0_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly
  perf/x86/intel/lbr: Use setup_clear_cpu_cap() instead of clear_cpu_cap()
  ftrace,kcfi: Separate ftrace_stub() and ftrace_stub_graph()
  x86/ftrace: Remove ftrace_epilogue()
  x86/resctrl: Fix min_cbm_bits for AMD
  x86/microcode/AMD: Apply the patch early on every logical thread
  x86/topology: Fix duplicated core ID within a package
  x86/topology: Fix multiple packages shown on a single-package system
  hwmon/coretemp: Handle large core ID value
  x86/Kconfig: Drop check for -mabi=ms for CONFIG_EFI_STUB
  x86/fpu: Exclude dynamic states from init_fpstate
  x86/fpu: Fix the init_fpstate size check with the actual size
  x86/fpu: Configure init_fpstate attributes orderly
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 fixes from Borislav Petkov:
 "As usually the case, right after a major release, the tip urgent
  branches accumulate a couple more fixes than normal. And here is the
  x86, a bit bigger, urgent pile.

   - Use the correct CPU capability clearing function on the error path
     in Intel perf LBR

   - A CFI fix to ftrace along with a simplification

   - Adjust handling of zero capacity bit mask for resctrl cache
     allocation on AMD

   - A fix to the AMD microcode loader to attempt patch application on
     every logical thread

   - A couple of topology fixes to handle CPUID leaf 0x1f enumeration
     info properly

   - Drop a -mabi=ms compiler option check as both compilers support it
     now anyway

   - A couple of fixes to how the initial, statically allocated FPU
     buffer state is setup and its interaction with dynamic states at
     runtime"

* tag 'x86_urgent_for_v6.0_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly
  perf/x86/intel/lbr: Use setup_clear_cpu_cap() instead of clear_cpu_cap()
  ftrace,kcfi: Separate ftrace_stub() and ftrace_stub_graph()
  x86/ftrace: Remove ftrace_epilogue()
  x86/resctrl: Fix min_cbm_bits for AMD
  x86/microcode/AMD: Apply the patch early on every logical thread
  x86/topology: Fix duplicated core ID within a package
  x86/topology: Fix multiple packages shown on a single-package system
  hwmon/coretemp: Handle large core ID value
  x86/Kconfig: Drop check for -mabi=ms for CONFIG_EFI_STUB
  x86/fpu: Exclude dynamic states from init_fpstate
  x86/fpu: Fix the init_fpstate size check with the actual size
  x86/fpu: Configure init_fpstate attributes orderly
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: x86: Add compat handler for KVM_X86_SET_MSR_FILTER</title>
<updated>2022-10-22T09:16:04+00:00</updated>
<author>
<name>Alexander Graf</name>
<email>graf@amazon.com</email>
</author>
<published>2022-10-17T18:45:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1739c7017fb1d759965dcbab925ff5980a5318cb'/>
<id>1739c7017fb1d759965dcbab925ff5980a5318cb</id>
<content type='text'>
The KVM_X86_SET_MSR_FILTER ioctls contains a pointer in the passed in
struct which means it has a different struct size depending on whether
it gets called from 32bit or 64bit code.

This patch introduces compat code that converts from the 32bit struct to
its 64bit counterpart which then gets used going forward internally.
With this applied, 32bit QEMU can successfully set MSR bitmaps when
running on 64bit kernels.

Reported-by: Andrew Randrianasulu &lt;randrianasulu@gmail.com&gt;
Fixes: 1a155254ff937 ("KVM: x86: Introduce MSR filtering")
Signed-off-by: Alexander Graf &lt;graf@amazon.com&gt;
Message-Id: &lt;20221017184541.2658-4-graf@amazon.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The KVM_X86_SET_MSR_FILTER ioctls contains a pointer in the passed in
struct which means it has a different struct size depending on whether
it gets called from 32bit or 64bit code.

This patch introduces compat code that converts from the 32bit struct to
its 64bit counterpart which then gets used going forward internally.
With this applied, 32bit QEMU can successfully set MSR bitmaps when
running on 64bit kernels.

Reported-by: Andrew Randrianasulu &lt;randrianasulu@gmail.com&gt;
Fixes: 1a155254ff937 ("KVM: x86: Introduce MSR filtering")
Signed-off-by: Alexander Graf &lt;graf@amazon.com&gt;
Message-Id: &lt;20221017184541.2658-4-graf@amazon.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: x86: Copy filter arg outside kvm_vm_ioctl_set_msr_filter()</title>
<updated>2022-10-22T09:15:56+00:00</updated>
<author>
<name>Alexander Graf</name>
<email>graf@amazon.com</email>
</author>
<published>2022-10-17T18:45:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2e3272bc1790825c43d2c39690bf2836b81c6d36'/>
<id>2e3272bc1790825c43d2c39690bf2836b81c6d36</id>
<content type='text'>
In the next patch we want to introduce a second caller to
set_msr_filter() which constructs its own filter list on the stack.
Refactor the original function so it takes it as argument instead of
reading it through copy_from_user().

Signed-off-by: Alexander Graf &lt;graf@amazon.com&gt;
Message-Id: &lt;20221017184541.2658-3-graf@amazon.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In the next patch we want to introduce a second caller to
set_msr_filter() which constructs its own filter list on the stack.
Refactor the original function so it takes it as argument instead of
reading it through copy_from_user().

Signed-off-by: Alexander Graf &lt;graf@amazon.com&gt;
Message-Id: &lt;20221017184541.2658-3-graf@amazon.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kvm-riscv-fixes-6.1-1' of https://github.com/kvm-riscv/linux into HEAD</title>
<updated>2022-10-22T07:33:58+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-10-22T07:33:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=21e6075974c82808fc46ffc72384f2cc8074777f'/>
<id>21e6075974c82808fc46ffc72384f2cc8074777f</id>
<content type='text'>
KVM/riscv fixes for 6.1, take #1

- Fix compilation without RISCV_ISA_ZICBOM
- Fix kvm_riscv_vcpu_timer_pending() for Sstc
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
KVM/riscv fixes for 6.1, take #1

- Fix compilation without RISCV_ISA_ZICBOM
- Fix kvm_riscv_vcpu_timer_pending() for Sstc
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kvmarm-fixes-6.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD</title>
<updated>2022-10-22T07:33:26+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-10-22T07:33:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ebccb53e939d9ee211cd304e659498496c2e29c9'/>
<id>ebccb53e939d9ee211cd304e659498496c2e29c9</id>
<content type='text'>
KVM/arm64 fixes for 6.1, take #2

- Fix a bug preventing restoring an ITS containing mappings
  for very large and very sparse device topology

- Work around a relocation handling error when compiling
  the nVHE object with profile optimisation
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
KVM/arm64 fixes for 6.1, take #2

- Fix a bug preventing restoring an ITS containing mappings
  for very large and very sparse device topology

- Work around a relocation handling error when compiling
  the nVHE object with profile optimisation
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kvmarm-fixes-6.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD</title>
<updated>2022-10-22T07:32:23+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-10-22T07:32:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5834816829e6b80871d8ee1c3d173e0259a02d1f'/>
<id>5834816829e6b80871d8ee1c3d173e0259a02d1f</id>
<content type='text'>
KVM/arm64 fixes for 6.1, take #1

- Fix for stage-2 invalidation holding the VM MMU lock
  for too long by limiting the walk to the largest
  block mapping size

- Enable stack protection and branch profiling for VHE

- Two selftest fixes
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
KVM/arm64 fixes for 6.1, take #1

- Fix for stage-2 invalidation holding the VM MMU lock
  for too long by limiting the walk to the largest
  block mapping size

- Enable stack protection and branch profiling for VHE

- Two selftest fixes
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly</title>
<updated>2022-10-21T22:22:09+00:00</updated>
<author>
<name>Chang S. Bae</name>
<email>chang.seok.bae@intel.com</email>
</author>
<published>2022-10-21T18:58:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=471f0aa7fa64e23766a1473b32d9ec3f0718895a'/>
<id>471f0aa7fa64e23766a1473b32d9ec3f0718895a</id>
<content type='text'>
When an extended state component is not present in fpstate, but in init
state, the function copies from init_fpstate via copy_feature().

But, dynamic states are not present in init_fpstate because of all-zeros
init states. Then retrieving them from init_fpstate will explode like this:

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 ...
 RIP: 0010:memcpy_erms+0x6/0x10
  ? __copy_xstate_to_uabi_buf+0x381/0x870
  fpu_copy_guest_fpstate_to_uabi+0x28/0x80
  kvm_arch_vcpu_ioctl+0x14c/0x1460 [kvm]
  ? __this_cpu_preempt_check+0x13/0x20
  ? vmx_vcpu_put+0x2e/0x260 [kvm_intel]
  kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
  ? kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
  ? __fget_light+0xd4/0x130
  __x64_sys_ioctl+0xe3/0x910
  ? debug_smp_processor_id+0x17/0x20
  ? fpregs_assert_state_consistent+0x27/0x50
  do_syscall_64+0x3f/0x90
  entry_SYSCALL_64_after_hwframe+0x63/0xcd

Adjust the 'mask' to zero out the userspace buffer for the features that
are not available both from fpstate and from init_fpstate.

The dynamic features depend on the compacted XSAVE format. Ensure it is
enabled before reading XCOMP_BV in init_fpstate.

Fixes: 2308ee57d93d ("x86/fpu/amx: Enable the AMX feature in 64-bit mode")
Reported-by: Yuan Yao &lt;yuan.yao@intel.com&gt;
Suggested-by: Dave Hansen &lt;dave.hansen@intel.com&gt;
Signed-off-by: Chang S. Bae &lt;chang.seok.bae@intel.com&gt;
Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Tested-by: Yuan Yao &lt;yuan.yao@intel.com&gt;
Link: https://lore.kernel.org/lkml/BYAPR11MB3717EDEF2351C958F2C86EED95259@BYAPR11MB3717.namprd11.prod.outlook.com/
Link: https://lkml.kernel.org/r/20221021185844.13472-1-chang.seok.bae@intel.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When an extended state component is not present in fpstate, but in init
state, the function copies from init_fpstate via copy_feature().

But, dynamic states are not present in init_fpstate because of all-zeros
init states. Then retrieving them from init_fpstate will explode like this:

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 ...
 RIP: 0010:memcpy_erms+0x6/0x10
  ? __copy_xstate_to_uabi_buf+0x381/0x870
  fpu_copy_guest_fpstate_to_uabi+0x28/0x80
  kvm_arch_vcpu_ioctl+0x14c/0x1460 [kvm]
  ? __this_cpu_preempt_check+0x13/0x20
  ? vmx_vcpu_put+0x2e/0x260 [kvm_intel]
  kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
  ? kvm_vcpu_ioctl+0xea/0x6b0 [kvm]
  ? __fget_light+0xd4/0x130
  __x64_sys_ioctl+0xe3/0x910
  ? debug_smp_processor_id+0x17/0x20
  ? fpregs_assert_state_consistent+0x27/0x50
  do_syscall_64+0x3f/0x90
  entry_SYSCALL_64_after_hwframe+0x63/0xcd

Adjust the 'mask' to zero out the userspace buffer for the features that
are not available both from fpstate and from init_fpstate.

The dynamic features depend on the compacted XSAVE format. Ensure it is
enabled before reading XCOMP_BV in init_fpstate.

Fixes: 2308ee57d93d ("x86/fpu/amx: Enable the AMX feature in 64-bit mode")
Reported-by: Yuan Yao &lt;yuan.yao@intel.com&gt;
Suggested-by: Dave Hansen &lt;dave.hansen@intel.com&gt;
Signed-off-by: Chang S. Bae &lt;chang.seok.bae@intel.com&gt;
Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Tested-by: Yuan Yao &lt;yuan.yao@intel.com&gt;
Link: https://lore.kernel.org/lkml/BYAPR11MB3717EDEF2351C958F2C86EED95259@BYAPR11MB3717.namprd11.prod.outlook.com/
Link: https://lkml.kernel.org/r/20221021185844.13472-1-chang.seok.bae@intel.com
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/unwind/orc: Fix unreliable stack dump with gcov</title>
<updated>2022-10-21T12:56:42+00:00</updated>
<author>
<name>Chen Zhongjin</name>
<email>chenzhongjin@huawei.com</email>
</author>
<published>2022-07-27T03:15:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=230db82413c091bc16acee72650f48d419cebe49'/>
<id>230db82413c091bc16acee72650f48d419cebe49</id>
<content type='text'>
When a console stack dump is initiated with CONFIG_GCOV_PROFILE_ALL
enabled, show_trace_log_lvl() gets out of sync with the ORC unwinder,
causing the stack trace to show all text addresses as unreliable:

  # echo l &gt; /proc/sysrq-trigger
  [  477.521031] sysrq: Show backtrace of all active CPUs
  [  477.523813] NMI backtrace for cpu 0
  [  477.524492] CPU: 0 PID: 1021 Comm: bash Not tainted 6.0.0 #65
  [  477.525295] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-1.fc36 04/01/2014
  [  477.526439] Call Trace:
  [  477.526854]  &lt;TASK&gt;
  [  477.527216]  ? dump_stack_lvl+0xc7/0x114
  [  477.527801]  ? dump_stack+0x13/0x1f
  [  477.528331]  ? nmi_cpu_backtrace.cold+0xb5/0x10d
  [  477.528998]  ? lapic_can_unplug_cpu+0xa0/0xa0
  [  477.529641]  ? nmi_trigger_cpumask_backtrace+0x16a/0x1f0
  [  477.530393]  ? arch_trigger_cpumask_backtrace+0x1d/0x30
  [  477.531136]  ? sysrq_handle_showallcpus+0x1b/0x30
  [  477.531818]  ? __handle_sysrq.cold+0x4e/0x1ae
  [  477.532451]  ? write_sysrq_trigger+0x63/0x80
  [  477.533080]  ? proc_reg_write+0x92/0x110
  [  477.533663]  ? vfs_write+0x174/0x530
  [  477.534265]  ? handle_mm_fault+0x16f/0x500
  [  477.534940]  ? ksys_write+0x7b/0x170
  [  477.535543]  ? __x64_sys_write+0x1d/0x30
  [  477.536191]  ? do_syscall_64+0x6b/0x100
  [  477.536809]  ? entry_SYSCALL_64_after_hwframe+0x63/0xcd
  [  477.537609]  &lt;/TASK&gt;

This happens when the compiled code for show_stack() has a single word
on the stack, and doesn't use a tail call to show_stack_log_lvl().
(CONFIG_GCOV_PROFILE_ALL=y is the only known case of this.)  Then the
__unwind_start() skip logic hits an off-by-one bug and fails to unwind
all the way to the intended starting frame.

Fix it by reverting the following commit:

  f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks")

The original justification for that commit no longer exists.  That
original issue was later fixed in a different way, with the following
commit:

  f2ac57a4c49d ("x86/unwind/orc: Fix inactive tasks with stack pointer in %sp on GCC 10 compiled kernels")

Fixes: f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks")
Signed-off-by: Chen Zhongjin &lt;chenzhongjin@huawei.com&gt;
[jpoimboe: rewrite commit log]
Signed-off-by: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
Signed-off-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When a console stack dump is initiated with CONFIG_GCOV_PROFILE_ALL
enabled, show_trace_log_lvl() gets out of sync with the ORC unwinder,
causing the stack trace to show all text addresses as unreliable:

  # echo l &gt; /proc/sysrq-trigger
  [  477.521031] sysrq: Show backtrace of all active CPUs
  [  477.523813] NMI backtrace for cpu 0
  [  477.524492] CPU: 0 PID: 1021 Comm: bash Not tainted 6.0.0 #65
  [  477.525295] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-1.fc36 04/01/2014
  [  477.526439] Call Trace:
  [  477.526854]  &lt;TASK&gt;
  [  477.527216]  ? dump_stack_lvl+0xc7/0x114
  [  477.527801]  ? dump_stack+0x13/0x1f
  [  477.528331]  ? nmi_cpu_backtrace.cold+0xb5/0x10d
  [  477.528998]  ? lapic_can_unplug_cpu+0xa0/0xa0
  [  477.529641]  ? nmi_trigger_cpumask_backtrace+0x16a/0x1f0
  [  477.530393]  ? arch_trigger_cpumask_backtrace+0x1d/0x30
  [  477.531136]  ? sysrq_handle_showallcpus+0x1b/0x30
  [  477.531818]  ? __handle_sysrq.cold+0x4e/0x1ae
  [  477.532451]  ? write_sysrq_trigger+0x63/0x80
  [  477.533080]  ? proc_reg_write+0x92/0x110
  [  477.533663]  ? vfs_write+0x174/0x530
  [  477.534265]  ? handle_mm_fault+0x16f/0x500
  [  477.534940]  ? ksys_write+0x7b/0x170
  [  477.535543]  ? __x64_sys_write+0x1d/0x30
  [  477.536191]  ? do_syscall_64+0x6b/0x100
  [  477.536809]  ? entry_SYSCALL_64_after_hwframe+0x63/0xcd
  [  477.537609]  &lt;/TASK&gt;

This happens when the compiled code for show_stack() has a single word
on the stack, and doesn't use a tail call to show_stack_log_lvl().
(CONFIG_GCOV_PROFILE_ALL=y is the only known case of this.)  Then the
__unwind_start() skip logic hits an off-by-one bug and fails to unwind
all the way to the intended starting frame.

Fix it by reverting the following commit:

  f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks")

The original justification for that commit no longer exists.  That
original issue was later fixed in a different way, with the following
commit:

  f2ac57a4c49d ("x86/unwind/orc: Fix inactive tasks with stack pointer in %sp on GCC 10 compiled kernels")

Fixes: f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks")
Signed-off-by: Chen Zhongjin &lt;chenzhongjin@huawei.com&gt;
[jpoimboe: rewrite commit log]
Signed-off-by: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
Signed-off-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
