leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

powerpc/ftrace: Have arch_ftrace_get_regs() return NULL unless FL_SAVE_REGS is set

Browse Source 
When FL_SAVE_REGS is not set we get here via ftrace_caller()
which doesn't save all registers.

ftrace_caller() explicitely clears regs.msr, so we can rely
on it to know where we come from. We don't expect MSR register
to be 0 at all when involving ftrace.

Fixes: 40b035efe2 ("powerpc/ftrace: Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS")
Reported-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2f9a7e898c93cc7438ef5ccd47cb9c3a9c5b53ef.1644949750.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy
2022-02-15 19:31:24 +01:00
committed by Michael Ellerman
parent df45a55788
commit fc75f87337
2 changed files with 6 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/powerpc/include/asm/ftrace.h
View File

@@ -30,7 +30,8 @@ struct ftrace_regs {
static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)
{
return &fregs->regs;
/* We clear regs.msr in ftrace_call */
return fregs->regs.msr ? &fregs->regs : NULL;
}
static __always_inline void ftrace_instruction_pointer_set(struct ftrace_regs *fregs,