linux.git/arch/arm64/kernel/stacktrace.c, branch v5.19 Linux kernel source tree arm64: stacktrace: align with common naming 2022-04-22T14:33:14+00:00 Madhavan T. Venkataraman madvenka@linux.microsoft.com 2022-04-13T14:59:10+00:00 bd5552bc4807a87a6597c629204712c7df7284f4 For historical reasons, the naming of parameters and their types in the arm64 stacktrace code differs from that used in generic code and other architectures, even though the types are equivalent. For consistency and clarity, use the generic names. There should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Mark Brown <broonie@kernel.org> Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series. Link: https://lore.kernel.org/r/20220413145910.3060139-7-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
For historical reasons, the naming of parameters and their types in the
arm64 stacktrace code differs from that used in generic code and other
architectures, even though the types are equivalent.

For consistency and clarity, use the generic names.

There should be no functional change as a result of this patch.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series.
Link: https://lore.kernel.org/r/20220413145910.3060139-7-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: stacktrace: rename stackframe to unwind_state 2022-04-22T14:33:14+00:00 Madhavan T. Venkataraman madvenka@linux.microsoft.com 2022-04-13T14:59:09+00:00 e9d75a0ba87851187fe52493f1527229a7e101b3 Rename "struct stackframe" to "struct unwind_state" for consistency and better naming. Accordingly, rename variable/argument "frame" to "state". There should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Reviewed-by: Mark Brown <broonie@kernel.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series. Link: https://lore.kernel.org/r/20220413145910.3060139-6-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
Rename "struct stackframe" to "struct unwind_state" for consistency and
better naming. Accordingly, rename variable/argument "frame" to "state".

There should be no functional change as a result of this patch.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series.
Link: https://lore.kernel.org/r/20220413145910.3060139-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: stacktrace: rename unwinder functions 2022-04-22T14:33:14+00:00 Madhavan T. Venkataraman madvenka@linux.microsoft.com 2022-04-13T14:59:08+00:00 c797bd45480b41d1d988b0a74d8d5a7c615bd674 Rename unwinder functions for consistency and better naming. - Rename start_backtrace() to unwind_init(). - Rename unwind_frame() to unwind_next(). - Rename walk_stackframe() to unwind(). There should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Reviewed-by: Mark Brown <broonie@kernel.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series. Link: https://lore.kernel.org/r/20220413145910.3060139-5-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
Rename unwinder functions for consistency and better naming.

	- Rename start_backtrace() to unwind_init().
	- Rename unwind_frame() to unwind_next().
	- Rename walk_stackframe() to unwind().

There should be no functional change as a result of this patch.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series.
Link: https://lore.kernel.org/r/20220413145910.3060139-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: stacktrace: make struct stackframe private to stacktrace.c 2022-04-22T14:33:13+00:00 Mark Rutland mark.rutland@arm.com 2022-04-13T14:59:07+00:00 96bb1530c4f9039996bf95d28dcc957861558696 Now that arm64 uses arch_stack_walk() consistently, struct stackframe is only used within stacktrace.c. To make it easier to read and maintain this code, it would be nicer if the definition were there too. Move the definition into stacktrace.c. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Cc: Mark Brown <broonie@kernel.org> Cc: Will Deacon <will@kernel.org> Reviewed-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Reviwed-by: Mark Brown <broonie@kernel.org> Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series. Link: https://lore.kernel.org/r/20220413145910.3060139-4-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
Now that arm64 uses arch_stack_walk() consistently, struct stackframe is
only used within stacktrace.c. To make it easier to read and maintain
this code, it would be nicer if the definition were there too.

Move the definition into stacktrace.c.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviwed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series.
Link: https://lore.kernel.org/r/20220413145910.3060139-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: stacktrace: delete PCS comment 2022-04-22T14:33:13+00:00 Mark Rutland mark.rutland@arm.com 2022-04-13T14:59:06+00:00 cb86a41b35c8f5da93ee7370c11634b57509d22b The comment at the top of stacktrace.c isn't all that helpful, as it's not associated with the code which inspects the frame record, and the code example isn't representative of common code generation today. Delete it. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Cc: Mark Brown <broonie@kernel.org> Cc: Will Deacon <will@kernel.org> Reviewed-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Reviewed-by: Mark Brown <broonie@kernel.org> Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series. Link: https://lore.kernel.org/r/20220413145910.3060139-3-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
The comment at the top of stacktrace.c isn't all that helpful, as it's
not associated with the code which inspects the frame record, and the
code example isn't representative of common code generation today.

Delete it.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series.
Link: https://lore.kernel.org/r/20220413145910.3060139-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: stacktrace: remove NULL task check from unwind_frame() 2022-04-22T14:33:13+00:00 Madhavan T. Venkataraman madvenka@linux.microsoft.com 2022-04-13T14:59:05+00:00 4f6277e8ac397e5932d9af5c6b3dadefe81d53dc Currently, there is a check for a NULL task in unwind_frame(). It is not needed since all current callers pass a non-NULL task. There should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Reviewed-by: Mark Brown <broonie@kernel.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series. Link: https://lore.kernel.org/r/20220413145910.3060139-2-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
Currently, there is a check for a NULL task in unwind_frame(). It is not
needed since all current callers pass a non-NULL task.

There should be no functional change as a result of this patch.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com> for the series.
Link: https://lore.kernel.org/r/20220413145910.3060139-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: Mark start_backtrace() notrace and NOKPROBE_SYMBOL 2022-01-24T14:25:20+00:00 Masami Hiramatsu mhiramat@kernel.org 2022-01-24T08:17:54+00:00 1e0924bd09916fab795fc2a21ec1d148f24299fd Mark the start_backtrace() as notrace and NOKPROBE_SYMBOL because this function is called from ftrace and lockdep to get the caller address via return_address(). The lockdep is used in kprobes, it should also be NOKPROBE_SYMBOL. Fixes: b07f3499661c ("arm64: stacktrace: Move start_backtrace() out of the header") Cc: <stable@vger.kernel.org> # 5.13.x Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/164301227374.1433152.12808232644267107415.stgit@devnote2 Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
Mark the start_backtrace() as notrace and NOKPROBE_SYMBOL
because this function is called from ftrace and lockdep to
get the caller address via return_address(). The lockdep
is used in kprobes, it should also be NOKPROBE_SYMBOL.

Fixes: b07f3499661c ("arm64: stacktrace: Move start_backtrace() out of the header")
Cc: <stable@vger.kernel.org> # 5.13.x
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/164301227374.1433152.12808232644267107415.stgit@devnote2
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: Make some stacktrace functions private 2021-12-10T14:06:04+00:00 Mark Rutland mark.rutland@arm.com 2021-11-29T14:28:49+00:00 d2d1d2645cfd7230fd958fddbc5e7525c34f1374 Now that open-coded stack unwinds have been converted to arch_stack_walk(), we no longer need to expose any of unwind_frame(), walk_stackframe(), or start_backtrace() outside of stacktrace.c. Make those functions private to stacktrace.c, removing their prototypes from <asm/stacktrace.h> and marking them static. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Mark Brown <broonie@kernel.org> Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> Link: https://lore.kernel.org/r/20211129142849.3056714-10-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
Now that open-coded stack unwinds have been converted to
arch_stack_walk(), we no longer need to expose any of unwind_frame(),
walk_stackframe(), or start_backtrace() outside of stacktrace.c.

Make those functions private to stacktrace.c, removing their prototypes
from <asm/stacktrace.h> and marking them static.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Link: https://lore.kernel.org/r/20211129142849.3056714-10-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: Make dump_backtrace() use arch_stack_walk() 2021-12-10T14:06:04+00:00 Madhavan T. Venkataraman madvenka@linux.microsoft.com 2021-11-29T14:28:48+00:00 2dad6dc17bd0cefd03b42147c6fc9bbd81f7928a To enable RELIABLE_STACKTRACE and LIVEPATCH on arm64, we need to substantially rework arm64's unwinding code. As part of this, we want to minimize the set of unwind interfaces we expose, and avoid open-coding of unwind logic. Currently, dump_backtrace() walks the stack of the current task or a blocked task by calling stact_backtrace() and iterating unwind steps using unwind_frame(). This can be written more simply in terms of arch_stack_walk(), considering three distinct cases: 1) When unwinding a blocked task, start_backtrace() is called with the blocked task's saved PC and FP, and the unwind proceeds immediately from this point without skipping any entries. This is functionally equivalent to calling arch_stack_walk() with the blocked task, which will start with the task's saved PC and FP. There is no functional change to this case. 2) When unwinding the current task without regs, start_backtrace() is called with dump_backtrace() as the PC and __builtin_frame_address(0) as the next frame, and the unwind proceeds immediately without skipping. This is *almost* functionally equivalent to calling arch_stack_walk() for the current task, which will start with its caller (i.e. an offset into dump_backtrace()) as the PC, and the callers frame record as the next frame. The only difference being that dump_backtrace() will be reported with an offset (which is strictly more correct than currently). Otherwise there is no functional cahnge to this case. 3) When unwinding the current task with regs, start_backtrace() is called with dump_backtrace() as the PC and __builtin_frame_address(0) as the next frame, and the unwind is performed silently until the next frame is the frame pointed to by regs->fp. Reporting starts from regs->pc and continues from the frame in regs->fp. Historically, this pre-unwind was necessary to correctly record return addresses rewritten by the ftrace graph calller, but this is no longer necessary as these are now recovered using the FP since commit: c6d3cd32fd0064af ("arm64: ftrace: use HAVE_FUNCTION_GRAPH_RET_ADDR_PTR") This pre-unwind is not necessary to recover return addresses rewritten by kretprobes, which historically were not recovered, and are now recovered using the FP since commit: cd9bc2c9258816dc ("arm64: Recover kretprobe modified return address in stacktrace") Thus, this is functionally equivalent to calling arch_stack_walk() with the current task and regs, which will start with regs->pc as the PC and regs->fp as the next frame, without a pre-unwind. This patch makes dump_backtrace() use arch_stack_walk(). This simplifies dump_backtrace() and will permit subsequent changes to the unwind code. Aside from the improved reporting when unwinding current without regs, there should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> [Mark: elaborate commit message] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211129142849.3056714-9-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
To enable RELIABLE_STACKTRACE and LIVEPATCH on arm64, we need to
substantially rework arm64's unwinding code. As part of this, we want to
minimize the set of unwind interfaces we expose, and avoid open-coding
of unwind logic.

Currently, dump_backtrace() walks the stack of the current task or a
blocked task by calling stact_backtrace() and iterating unwind steps
using unwind_frame(). This can be written more simply in terms of
arch_stack_walk(), considering three distinct cases:

1) When unwinding a blocked task, start_backtrace() is called with the
   blocked task's saved PC and FP, and the unwind proceeds immediately
   from this point without skipping any entries. This is functionally
   equivalent to calling arch_stack_walk() with the blocked task, which
   will start with the task's saved PC and FP.

   There is no functional change to this case.

2) When unwinding the current task without regs, start_backtrace() is
   called with dump_backtrace() as the PC and __builtin_frame_address(0)
   as the next frame, and the unwind proceeds immediately without
   skipping. This is *almost* functionally equivalent to calling
   arch_stack_walk() for the current task, which will start with its
   caller (i.e. an offset into dump_backtrace()) as the PC, and the
   callers frame record as the next frame.

   The only difference being that dump_backtrace() will be reported with
   an offset (which is strictly more correct than currently). Otherwise
   there is no functional cahnge to this case.

3) When unwinding the current task with regs, start_backtrace() is
   called with dump_backtrace() as the PC and __builtin_frame_address(0)
   as the next frame, and the unwind is performed silently until the
   next frame is the frame pointed to by regs->fp. Reporting starts
   from regs->pc and continues from the frame in regs->fp.

   Historically, this pre-unwind was necessary to correctly record
   return addresses rewritten by the ftrace graph calller, but this is
   no longer necessary as these are now recovered using the FP since
   commit:

   c6d3cd32fd0064af ("arm64: ftrace: use HAVE_FUNCTION_GRAPH_RET_ADDR_PTR")

   This pre-unwind is not necessary to recover return addresses
   rewritten by kretprobes, which historically were not recovered, and
   are now recovered using the FP since commit:

   cd9bc2c9258816dc ("arm64: Recover kretprobe modified return address in stacktrace")

   Thus, this is functionally equivalent to calling arch_stack_walk()
   with the current task and regs, which will start with regs->pc as the
   PC and regs->fp as the next frame, without a pre-unwind.

This patch makes dump_backtrace() use arch_stack_walk(). This simplifies
dump_backtrace() and will permit subsequent changes to the unwind code.

Aside from the improved reporting when unwinding current without regs,
there should be no functional change as a result of this patch.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
[Mark: elaborate commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211129142849.3056714-9-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arch: Make ARCH_STACKWALK independent of STACKTRACE 2021-12-10T14:06:03+00:00 Peter Zijlstra peterz@infradead.org 2021-11-29T14:28:41+00:00 1614b2b11fab29dd4ff31ebba9d266961f5af69e Make arch_stack_walk() available for ARCH_STACKWALK architectures without it being entangled in STACKTRACE. Link: https://lore.kernel.org/lkml/20211022152104.356586621@infradead.org/ Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [Mark: rebase, drop unnecessary arm change] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Borislav Petkov <bp@alien8.de> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Link: https://lore.kernel.org/r/20211129142849.3056714-2-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
Make arch_stack_walk() available for ARCH_STACKWALK architectures
without it being entangled in STACKTRACE.

Link: https://lore.kernel.org/lkml/20211022152104.356586621@infradead.org/
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[Mark: rebase, drop unnecessary arm change]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20211129142849.3056714-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>