diff options
| author |   Christophe Leroy <christophe.leroy@csgroup.eu> | 2022-02-15 19:31:24 +0100 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2022-02-16 23:09:47 +1100 |
| commit | fc75f87337983229b7355d6b77f30fb6e7f359ee (patch) | |
| tree | 32347525d29a13a6f59063034c8236c47319aac5 /arch | |
| parent | powerpc/ftrace: Add recursion protection in prepare_ftrace_return() (diff) | |
| download | linux-dev-fc75f87337983229b7355d6b77f30fb6e7f359ee.tar.xz linux-dev-fc75f87337983229b7355d6b77f30fb6e7f359ee.zip | |
powerpc/ftrace: Have arch_ftrace_get_regs() return NULL unless FL_SAVE_REGS is set
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: 40b035efe288 ("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
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/include/asm/ftrace.h | 3 | ||||
| -rw-r--r-- | arch/powerpc/kernel/trace/ftrace_mprofile.S | 4 |
2 files changed, 6 insertions, 1 deletions
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 |