linux.git/arch/powerpc/kernel/stacktrace.c, branch v5.10

kernel: rename show_stack_loglvl() => show_stack()

2020-06-09T16:39:13+00:00

Now the last users of show_stack() got converted to use an explicit log
level, show_stack_loglvl() can drop it's redundant suffix and become once
again well known show_stack().

Signed-off-by: Dmitry Safonov 
Signed-off-by: Andrew Morton 
Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com
Signed-off-by: Linus Torvalds

powerpc: Rename current_stack_pointer() to current_stack_frame()

2020-03-04T11:44:28+00:00

current_stack_pointer(), which was called __get_SP(), used to just
return the value in r1.

But that caused problems in some cases, so it was turned into a
function in commit bfe9a2cfe91a ("powerpc: Reimplement __get_SP() as a
function not a define").

Because it's a function in a separate compilation unit to all its
callers, it has the effect of causing a stack frame to be created, and
then returns the address of that frame. This is good in some cases
like those described in the above commit, but in other cases it's
overkill, we just need to know what stack page we're on.

On some other arches current_stack_pointer is just a register global
giving the stack pointer, and we'd like to do that too. So rename our
current_stack_pointer() to current_stack_frame() to make that
possible.

Signed-off-by: Michael Ellerman 
Reviewed-by: Christophe Leroy 
Link: https://lore.kernel.org/r/20200220115141.2707-1-mpe@ellerman.id.au

powerpc/ftrace: Enable HAVE_FUNCTION_GRAPH_RET_ADDR_PTR

2019-09-18T02:24:55+00:00

This associates entries in the ftrace_ret_stack with corresponding stack
frames, enabling more robust stack unwinding. Also update the only user
of ftrace_graph_ret_addr() to pass the stack pointer.

Signed-off-by: Naveen N. Rao 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/0224f2d0971b069c678e2ff678cfc2cd1e114cfe.1567707399.git.naveen.n.rao@linux.vnet.ibm.com

powerpc: Remove export of save_stack_trace_tsk_reliable()

2019-03-02T03:43:05+00:00

As tglx points out, there are no in-tree module users of
save_stack_trace_tsk_reliable() and its x86 counterpart is not
exported, so remove the powerpc symbol export.

Suggested-by: Thomas Gleixner 
Signed-off-by: Joe Lawrence 
Signed-off-by: Michael Ellerman

powerpc: prep stack walkers for THREAD_INFO_IN_TASK

2019-02-23T11:31:40+00:00

[text copied from commit 9bbd4c56b0b6
("arm64: prep stack walkers for THREAD_INFO_IN_TASK")]

When CONFIG_THREAD_INFO_IN_TASK is selected, task stacks may be freed
before a task is destroyed. To account for this, the stacks are
refcounted, and when manipulating the stack of another task, it is
necessary to get/put the stack to ensure it isn't freed and/or re-used
while we do so.

This patch reworks the powerpc stack walking code to account for this.
When CONFIG_THREAD_INFO_IN_TASK is not selected these perform no
refcounting, and this should only be a structural change that does not
affect behaviour.

Acked-by: Mark Rutland 
Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
[mpe: Move try_get_task_stack() below tsk == NULL check in show_stack()]
Signed-off-by: Michael Ellerman

powerpc/livepatch: return -ERRNO values in save_stack_trace_tsk_reliable()

2019-01-31T05:43:38+00:00

To match its x86 counterpart, save_stack_trace_tsk_reliable() should
return -EINVAL in cases that it is currently returning 1.  No caller is
currently differentiating non-zero error codes, but let's keep the
arch-specific implementations consistent.

Signed-off-by: Joe Lawrence 
Signed-off-by: Michael Ellerman

powerpc/livepatch: small cleanups in save_stack_trace_tsk_reliable()

2019-01-31T05:43:38+00:00

Mostly cosmetic changes:

- Group common stack pointer code at the top
- Simplify the first frame logic
- Code stackframe iteration into for...loop construct
- Check for trace->nr_entries overflow before adding any into the array

Suggested-by: Nicolai Stange 
Signed-off-by: Joe Lawrence 
Signed-off-by: Michael Ellerman

powerpc/livepatch: relax reliable stack tracer checks for first-frame

2019-01-31T05:43:38+00:00

The bottom-most stack frame (the first to be unwound) may be largely
uninitialized, for the "Power Architecture 64-Bit ELF V2 ABI" only
requires its backchain pointer to be set.

The reliable stack tracer should be careful when verifying this frame:
skip checks on STACK_FRAME_LR_SAVE and STACK_FRAME_MARKER offsets that
may contain uninitialized residual data.

Fixes: df78d3f61480 ("powerpc/livepatch: Implement reliable stack tracing for the consistency model")
Signed-off-by: Joe Lawrence 
Signed-off-by: Michael Ellerman

powerpc/64s: Fix build failures with CONFIG_NMI_IPI=n

2018-06-19T13:03:50+00:00

I broke the build when CONFIG_NMI_IPI=n with my recent commit to add
arch_trigger_cpumask_backtrace(), eg:

  stacktrace.c:(.text+0x1b0): undefined reference to `.smp_send_safe_nmi_ipi'

We should rework the CONFIG symbols here in future to avoid these
double barrelled ifdefs but for now they fix the build.

Fixes: 5cc05910f26e ("powerpc/64s: Wire up arch_trigger_cpumask_backtrace()")
Reported-by: Christophe LEROY 
Signed-off-by: Michael Ellerman

powerpc/stacktrace: Update copyright

2018-06-03T10:43:43+00:00

This now has new code in it written by Nick and I, and switch to a
SPDX tag.

Signed-off-by: Michael Ellerman 
Reviewed-by: Nicholas Piggin