linux.git/arch/arm64/include/asm/stacktrace.h, branch v5.10 Linux kernel source tree arm64: stacktrace: Make stack walk callback consistent with generic code 2020-09-18T13:24:16+00:00 Mark Brown broonie@kernel.org 2020-09-14T15:34:08+00:00 baa2cd417053cb674deb90ee66b88afea0517335 As with the generic arch_stack_walk() code the arm64 stack walk code takes a callback that is called per stack frame. Currently the arm64 code always passes a struct stackframe to the callback and the generic code just passes the pc, however none of the users ever reference anything in the struct other than the pc value. The arm64 code also uses a return type of int while the generic code uses a return type of bool though in both cases the return value is a boolean value and the sense is inverted between the two. In order to reduce code duplication when arm64 is converted to use arch_stack_walk() change the signature and return sense of the arm64 specific callback to match that of the generic code. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/20200914153409.25097-3-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org> 
As with the generic arch_stack_walk() code the arm64 stack walk code takes
a callback that is called per stack frame. Currently the arm64 code always
passes a struct stackframe to the callback and the generic code just passes
the pc, however none of the users ever reference anything in the struct
other than the pc value. The arm64 code also uses a return type of int
while the generic code uses a return type of bool though in both cases the
return value is a boolean value and the sense is inverted between the two.

In order to reduce code duplication when arm64 is converted to use
arch_stack_walk() change the signature and return sense of the arm64
specific callback to match that of the generic code.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20200914153409.25097-3-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
arm64: add loglvl to dump_backtrace() 2020-06-09T16:39:11+00:00 Dmitry Safonov dima@arista.com 2020-06-09T04:30:23+00:00 c76898373f9b71586edaf150190c493ae9ed3e77 Currently, the log-level of show_stack() depends on a platform realization. It creates situations where the headers are printed with lower log level or higher than the stacktrace (depending on a platform or user). Furthermore, it forces the logic decision from user to an architecture side. In result, some users as sysrq/kdb/etc are doing tricks with temporary rising console_loglevel while printing their messages. And in result it not only may print unwanted messages from other CPUs, but also omit printing at all in the unlucky case where the printk() was deferred. Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems an easier approach than introducing more printk buffers. Also, it will consolidate printings with headers. Add log level argument to dump_backtrace() as a preparation for introducing show_stack_loglvl(). [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will@kernel.org> Link: http://lkml.kernel.org/r/20200418201944.482088-10-dima@arista.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Currently, the log-level of show_stack() depends on a platform
realization.  It creates situations where the headers are printed with
lower log level or higher than the stacktrace (depending on a platform or
user).

Furthermore, it forces the logic decision from user to an architecture
side.  In result, some users as sysrq/kdb/etc are doing tricks with
temporary rising console_loglevel while printing their messages.  And in
result it not only may print unwanted messages from other CPUs, but also
omit printing at all in the unlucky case where the printk() was deferred.

Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems an easier
approach than introducing more printk buffers.  Also, it will consolidate
printings with headers.

Add log level argument to dump_backtrace() as a preparation for
introducing show_stack_loglvl().

[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will@kernel.org>
Link: http://lkml.kernel.org/r/20200418201944.482088-10-dima@arista.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arm64: stacktrace: Factor out some common code into on_stack() 2020-05-18T17:04:22+00:00 Yunfeng Ye yeyunfeng@huawei.com 2020-05-08T03:15:45+00:00 bd4298c72b56d7faf0ee3671739f3a704a962d0f There are some common codes for stack checking, so factors it out into the function on_stack(). No functional change. Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com> Link: https://lore.kernel.org/r/07b3b0e6-3f58-4fed-07ea-7d17b7508948@huawei.com Signed-off-by: Will Deacon <will@kernel.org> 
There are some common codes for stack checking, so factors it out into
the function on_stack().

No functional change.

Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Link: https://lore.kernel.org/r/07b3b0e6-3f58-4fed-07ea-7d17b7508948@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
arm64: stacktrace: Better handle corrupted stacks 2019-07-22T10:44:15+00:00 Mark Rutland mark.rutland@arm.com 2019-07-02T13:07:29+00:00 592700f094be229b5c9cc1192d5cea46eb4c7afc The arm64 stacktrace code is careful to only dereference frame records in valid stack ranges, ensuring that a corrupted frame record won't result in a faulting access. However, it's still possible for corrupt frame records to result in infinite loops in the stacktrace code, which is also undesirable. This patch ensures that we complete a stacktrace in finite time, by keeping track of which stacks we have already completed unwinding, and verifying that if the next frame record is on the same stack, it is at a higher address. As this has turned out to be particularly subtle, comments are added to explain the procedure. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: James Morse <james.morse@arm.com> Tested-by: James Morse <james.morse@arm.com> Acked-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Tengfei Fan <tengfeif@codeaurora.org> Signed-off-by: Will Deacon <will@kernel.org> 
The arm64 stacktrace code is careful to only dereference frame records
in valid stack ranges, ensuring that a corrupted frame record won't
result in a faulting access.

However, it's still possible for corrupt frame records to result in
infinite loops in the stacktrace code, which is also undesirable.

This patch ensures that we complete a stacktrace in finite time, by
keeping track of which stacks we have already completed unwinding, and
verifying that if the next frame record is on the same stack, it is at a
higher address.

As this has turned out to be particularly subtle, comments are added to
explain the procedure.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Tested-by: James Morse <james.morse@arm.com>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tengfei Fan <tengfeif@codeaurora.org>
Signed-off-by: Will Deacon <will@kernel.org>
arm64: stacktrace: Factor out backtrace initialisation 2019-07-22T10:44:08+00:00 Dave Martin Dave.Martin@arm.com 2019-07-02T13:07:28+00:00 f3dcbe67ed424f1cf92065f9ad0cc647f2b44eac Some common code is required by each stacktrace user to initialise struct stackframe before the first call to unwind_frame(). In preparation for adding to the common code, this patch factors it out into a separate function start_backtrace(), and modifies the stacktrace callers appropriately. No functional change. Signed-off-by: Dave Martin <dave.martin@arm.com> [Mark: drop tsk argument, update more callsites] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: James Morse <james.morse@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will@kernel.org> 
Some common code is required by each stacktrace user to initialise
struct stackframe before the first call to unwind_frame().

In preparation for adding to the common code, this patch factors it
out into a separate function start_backtrace(), and modifies the
stacktrace callers appropriately.

No functional change.

Signed-off-by: Dave Martin <dave.martin@arm.com>
[Mark: drop tsk argument, update more callsites]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
arm64: stacktrace: Constify stacktrace.h functions 2019-07-22T10:44:00+00:00 Dave Martin Dave.Martin@arm.com 2019-07-02T13:07:27+00:00 8caa6e2be72313c170f2b30e8475323526dd7ed1 on_accessible_stack() and on_task_stack() shouldn't (and don't) modify their task argument, so it can be const. This patch adds the appropriate modifiers. Whitespace violations in the parameter lists are fixed at the same time. No functional change. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Dave Martin <dave.martin@arm.com> [Mark: fixup const location, whitespace] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org> 
on_accessible_stack() and on_task_stack() shouldn't (and don't)
modify their task argument, so it can be const.

This patch adds the appropriate modifiers. Whitespace violations in the
parameter lists are fixed at the same time.

No functional change.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Dave Martin <dave.martin@arm.com>
[Mark: fixup const location, whitespace]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234 2019-06-19T15:09:07+00:00 Thomas Gleixner tglx@linutronix.de 2019-06-03T05:44:50+00:00 caab277b1de0a22b675c4c95fc7b285ec2eb5bf5 Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 503 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Enrico Weigelt <info@metux.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation this program is
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details you should have received a copy of the gnu general
  public license along with this program if not see http www gnu org
  licenses

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 503 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arm64: Add stack information to on_accessible_stack 2018-07-26T10:36:07+00:00 Laura Abbott labbott@redhat.com 2018-07-20T21:41:53+00:00 8a1ccfbc9e0256baafbbce85ccdb72ec89af2aab In preparation for enabling the stackleak plugin on arm64, we need a way to get the bounds of the current stack. Extend on_accessible_stack to get this information. Acked-by: Alexander Popov <alex.popov@linux.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Laura Abbott <labbott@redhat.com> [will: folded in fix for allmodconfig build breakage w/ sdei] Signed-off-by: Will Deacon <will.deacon@arm.com> 
In preparation for enabling the stackleak plugin on arm64,
we need a way to get the bounds of the current stack. Extend
on_accessible_stack to get this information.

Acked-by: Alexander Popov <alex.popov@linux.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
[will: folded in fix for allmodconfig build breakage w/ sdei]
Signed-off-by: Will Deacon <will.deacon@arm.com>
arm64: fix unwind_frame() for filtered out fn for function graph tracing 2018-02-23T13:46:38+00:00 Pratyush Anand panand@redhat.com 2018-02-05T13:28:01+00:00 9f416319f40cd857d2bb517630e5855a905ef3fb do_task_stat() calls get_wchan(), which further does unwind_frame(). unwind_frame() restores frame->pc to original value in case function graph tracer has modified a return address (LR) in a stack frame to hook a function return. However, if function graph tracer has hit a filtered function, then we can't unwind it as ftrace_push_return_trace() has biased the index(frame->graph) with a 'huge negative' offset(-FTRACE_NOTRACE_DEPTH). Moreover, arm64 stack walker defines index(frame->graph) as unsigned int, which can not compare a -ve number. Similar problem we can have with calling of walk_stackframe() from save_stack_trace_tsk() or dump_backtrace(). This patch fixes unwind_frame() to test the index for -ve value and restore index accordingly before we can restore frame->pc. Reproducer: cd /sys/kernel/debug/tracing/ echo schedule > set_graph_notrace echo 1 > options/display-graph echo wakeup > current_tracer ps -ef | grep -i agent Above commands result in: Unable to handle kernel paging request at virtual address ffff801bd3d1e000 pgd = ffff8003cbe97c00 [ffff801bd3d1e000] *pgd=0000000000000000, *pud=0000000000000000 Internal error: Oops: 96000006 [#1] SMP [...] CPU: 5 PID: 11696 Comm: ps Not tainted 4.11.0+ #33 [...] task: ffff8003c21ba000 task.stack: ffff8003cc6c0000 PC is at unwind_frame+0x12c/0x180 LR is at get_wchan+0xd4/0x134 pc : [<ffff00000808892c>] lr : [<ffff0000080860b8>] pstate: 60000145 sp : ffff8003cc6c3ab0 x29: ffff8003cc6c3ab0 x28: 0000000000000001 x27: 0000000000000026 x26: 0000000000000026 x25: 00000000000012d8 x24: 0000000000000000 x23: ffff8003c1c04000 x22: ffff000008c83000 x21: ffff8003c1c00000 x20: 000000000000000f x19: ffff8003c1bc0000 x18: 0000fffffc593690 x17: 0000000000000000 x16: 0000000000000001 x15: 0000b855670e2b60 x14: 0003e97f22cf1d0f x13: 0000000000000001 x12: 0000000000000000 x11: 00000000e8f4883e x10: 0000000154f47ec8 x9 : 0000000070f367c0 x8 : 0000000000000000 x7 : 00008003f7290000 x6 : 0000000000000018 x5 : 0000000000000000 x4 : ffff8003c1c03cb0 x3 : ffff8003c1c03ca0 x2 : 00000017ffe80000 x1 : ffff8003cc6c3af8 x0 : ffff8003d3e9e000 Process ps (pid: 11696, stack limit = 0xffff8003cc6c0000) Stack: (0xffff8003cc6c3ab0 to 0xffff8003cc6c4000) [...] [<ffff00000808892c>] unwind_frame+0x12c/0x180 [<ffff000008305008>] do_task_stat+0x864/0x870 [<ffff000008305c44>] proc_tgid_stat+0x3c/0x48 [<ffff0000082fde0c>] proc_single_show+0x5c/0xb8 [<ffff0000082b27e0>] seq_read+0x160/0x414 [<ffff000008289e6c>] __vfs_read+0x58/0x164 [<ffff00000828b164>] vfs_read+0x88/0x144 [<ffff00000828c2e8>] SyS_read+0x60/0xc0 [<ffff0000080834a0>] __sys_trace_return+0x0/0x4 Fixes: 20380bb390a4 (arm64: ftrace: fix a stack tracer's output under function graph tracer) Signed-off-by: Pratyush Anand <panand@redhat.com> Signed-off-by: Jerome Marchand <jmarchan@redhat.com> [catalin.marinas@arm.com: replace WARN_ON with WARN_ON_ONCE] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
do_task_stat() calls get_wchan(), which further does unwind_frame().
unwind_frame() restores frame->pc to original value in case function
graph tracer has modified a return address (LR) in a stack frame to hook
a function return. However, if function graph tracer has hit a filtered
function, then we can't unwind it as ftrace_push_return_trace() has
biased the index(frame->graph) with a 'huge negative'
offset(-FTRACE_NOTRACE_DEPTH).

Moreover, arm64 stack walker defines index(frame->graph) as unsigned
int, which can not compare a -ve number.

Similar problem we can have with calling of walk_stackframe() from
save_stack_trace_tsk() or dump_backtrace().

This patch fixes unwind_frame() to test the index for -ve value and
restore index accordingly before we can restore frame->pc.

Reproducer:

cd /sys/kernel/debug/tracing/
echo schedule > set_graph_notrace
echo 1 > options/display-graph
echo wakeup > current_tracer
ps -ef | grep -i agent

Above commands result in:
Unable to handle kernel paging request at virtual address ffff801bd3d1e000
pgd = ffff8003cbe97c00
[ffff801bd3d1e000] *pgd=0000000000000000, *pud=0000000000000000
Internal error: Oops: 96000006 [#1] SMP
[...]
CPU: 5 PID: 11696 Comm: ps Not tainted 4.11.0+ #33
[...]
task: ffff8003c21ba000 task.stack: ffff8003cc6c0000
PC is at unwind_frame+0x12c/0x180
LR is at get_wchan+0xd4/0x134
pc : [<ffff00000808892c>] lr : [<ffff0000080860b8>] pstate: 60000145
sp : ffff8003cc6c3ab0
x29: ffff8003cc6c3ab0 x28: 0000000000000001
x27: 0000000000000026 x26: 0000000000000026
x25: 00000000000012d8 x24: 0000000000000000
x23: ffff8003c1c04000 x22: ffff000008c83000
x21: ffff8003c1c00000 x20: 000000000000000f
x19: ffff8003c1bc0000 x18: 0000fffffc593690
x17: 0000000000000000 x16: 0000000000000001
x15: 0000b855670e2b60 x14: 0003e97f22cf1d0f
x13: 0000000000000001 x12: 0000000000000000
x11: 00000000e8f4883e x10: 0000000154f47ec8
x9 : 0000000070f367c0 x8 : 0000000000000000
x7 : 00008003f7290000 x6 : 0000000000000018
x5 : 0000000000000000 x4 : ffff8003c1c03cb0
x3 : ffff8003c1c03ca0 x2 : 00000017ffe80000
x1 : ffff8003cc6c3af8 x0 : ffff8003d3e9e000

Process ps (pid: 11696, stack limit = 0xffff8003cc6c0000)
Stack: (0xffff8003cc6c3ab0 to 0xffff8003cc6c4000)
[...]
[<ffff00000808892c>] unwind_frame+0x12c/0x180
[<ffff000008305008>] do_task_stat+0x864/0x870
[<ffff000008305c44>] proc_tgid_stat+0x3c/0x48
[<ffff0000082fde0c>] proc_single_show+0x5c/0xb8
[<ffff0000082b27e0>] seq_read+0x160/0x414
[<ffff000008289e6c>] __vfs_read+0x58/0x164
[<ffff00000828b164>] vfs_read+0x88/0x144
[<ffff00000828c2e8>] SyS_read+0x60/0xc0
[<ffff0000080834a0>] __sys_trace_return+0x0/0x4

Fixes: 20380bb390a4 (arm64: ftrace: fix a stack tracer's output under function graph tracer)
Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
[catalin.marinas@arm.com: replace WARN_ON with WARN_ON_ONCE]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arm64: kernel: Add arch-specific SDEI entry code and CPU masking 2018-01-13T10:45:17+00:00 James Morse james.morse@arm.com 2018-01-08T15:38:12+00:00 f5df26961853d6809d704cedcaf082c57f635a64 The Software Delegated Exception Interface (SDEI) is an ARM standard for registering callbacks from the platform firmware into the OS. This is typically used to implement RAS notifications. Such notifications enter the kernel at the registered entry-point with the register values of the interrupted CPU context. Because this is not a CPU exception, it cannot reuse the existing entry code. (crucially we don't implicitly know which exception level we interrupted), Add the entry point to entry.S to set us up for calling into C code. If the event interrupted code that had interrupts masked, we always return to that location. Otherwise we pretend this was an IRQ, and use SDEI's complete_and_resume call to return to vbar_el1 + offset. This allows the kernel to deliver signals to user space processes. For KVM this triggers the world switch, a quick spin round vcpu_run, then back into the guest, unless there are pending signals. Add sdei_mask_local_cpu() calls to the smp_send_stop() code, this covers the panic() code-path, which doesn't invoke cpuhotplug notifiers. Because we can interrupt entry-from/exit-to another EL, we can't trust the value in sp_el0 or x29, even if we interrupted the kernel, in this case the code in entry.S will save/restore sp_el0 and use the value in __entry_task. When we have VMAP stacks we can interrupt the stack-overflow test, which stirs x0 into sp, meaning we have to have our own VMAP stacks. For now these are allocated when we probe the interface. Future patches will add refcounting hooks to allow the arch code to allocate them lazily. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> 
The Software Delegated Exception Interface (SDEI) is an ARM standard
for registering callbacks from the platform firmware into the OS.
This is typically used to implement RAS notifications.

Such notifications enter the kernel at the registered entry-point
with the register values of the interrupted CPU context. Because this
is not a CPU exception, it cannot reuse the existing entry code.
(crucially we don't implicitly know which exception level we interrupted),

Add the entry point to entry.S to set us up for calling into C code. If
the event interrupted code that had interrupts masked, we always return
to that location. Otherwise we pretend this was an IRQ, and use SDEI's
complete_and_resume call to return to vbar_el1 + offset.

This allows the kernel to deliver signals to user space processes. For
KVM this triggers the world switch, a quick spin round vcpu_run, then
back into the guest, unless there are pending signals.

Add sdei_mask_local_cpu() calls to the smp_send_stop() code, this covers
the panic() code-path, which doesn't invoke cpuhotplug notifiers.

Because we can interrupt entry-from/exit-to another EL, we can't trust the
value in sp_el0 or x29, even if we interrupted the kernel, in this case
the code in entry.S will save/restore sp_el0 and use the value in
__entry_task.

When we have VMAP stacks we can interrupt the stack-overflow test, which
stirs x0 into sp, meaning we have to have our own VMAP stacks. For now
these are allocated when we probe the interface. Future patches will add
refcounting hooks to allow the arch code to allocate them lazily.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>