| Message ID | 2f9a7e898c93cc7438ef5ccd47cb9c3a9c5b53ef.1644949750.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v1,1/4] powerpc/ftrace: Also save r1 in ftrace_caller() | expand |
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 70b457097098..ff034ae4e472 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -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, diff --git a/arch/powerpc/kernel/trace/ftrace_mprofile.S b/arch/powerpc/kernel/trace/ftrace_mprofile.S index 8443902d5a05..eb077270ec2f 100644 --- a/arch/powerpc/kernel/trace/ftrace_mprofile.S +++ b/arch/powerpc/kernel/trace/ftrace_mprofile.S @@ -205,6 +205,10 @@ _GLOBAL(ftrace_caller) PPC_STL r0, _LINK(r1) mr r4, r0 + /* Clear MSR to flag as ftrace_caller versus frace_regs_caller */ + li r8, 0 + PPC_STL r8, _MSR(r1) + /* Load &pt_regs in r6 for call below */ addi r6, r1 ,STACK_FRAME_OVERHEAD
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. Reported-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Fixes: 40b035efe288 ("powerpc/ftrace: Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/powerpc/include/asm/ftrace.h | 3 ++- arch/powerpc/kernel/trace/ftrace_mprofile.S | 4 ++++ 2 files changed, 6 insertions(+), 1 deletion(-)