shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-07 11:26:02 +09:00
Code Issues Packages Projects Releases Wiki Activity

UPSTREAM: arm64: ftrace: modify a stack frame in a safe way

Browse Source 
Function graph tracer modifies a return address (LR) in a stack frame by
calling ftrace_prepare_return() in a traced function's function prologue.
The current code does this modification before preserving an original
address at ftrace_push_return_trace() and there is always a small window
of inconsistency when an interrupt occurs.

This doesn't matter, as far as an interrupt stack is introduced, because
stack tracer won't be invoked in an interrupt context. But it would be
better to proactively minimize such a window by moving the LR modification
after ftrace_push_return_trace().

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Bug: 30369029
Patchset: rework-pagetable

(cherry picked from commit 79fdee9b63)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: Ief0a136aa01348b4d0d3f447544f21fd77835c67
This commit is contained in:
AKASHI Takahiro
2015-12-15 17:33:39 +09:00
committed by Jeff Vander Stoep
parent 0c6cdfec12
commit cc6027395e
1 changed files with 4 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
arch/arm64/kernel/ftrace.c
View File

@@ -129,23 +129,20 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
* on other archs. It's unlikely on AArch64.
*/
old = *parent;
*parent = return_hooker;
trace.func = self_addr;
trace.depth = current->curr_ret_stack + 1;
/* Only trace if the calling function expects to */
if (!ftrace_graph_entry(&trace)) {
*parent = old;
if (!ftrace_graph_entry(&trace))
return;
}
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer);
if (err == -EBUSY) {
*parent = old;
if (err == -EBUSY)
return;
}
else
*parent = return_hooker;
}
#ifdef CONFIG_DYNAMIC_FTRACE