[PATCH v4 5/7] powerpc/64s: Un-blacklist system_call() from kprobes
From: Naveen N. Rao <hidden>
Date: 2017-06-29 10:41:48
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
It is actually safe to probe system_call() in entry_64.S, but only till we unset MSR_RI. To allow this, add a new symbol system_call_exit() after the mtmsrd and blacklist that. Though the mtmsrd instruction itself is now whitelisted, we won't be allowed to probe on it as we don't allow probing on rfi and mtmsr instructions (checked for in arch_prepare_kprobe()). Suggested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Naveen N. Rao <redacted> --- arch/powerpc/kernel/entry_64.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index c39436706555..7a87427a67cd 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S@@ -205,6 +205,7 @@ system_call: /* label this so stack traces look sane */ mtmsrd r11,1 #endif /* CONFIG_PPC_BOOK3E */ +system_call_exit: ld r9,TI_FLAGS(r12) li r11,-MAX_ERRNO andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
@@ -413,7 +414,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) b . /* prevent speculative execution */ #endif _ASM_NOKPROBE_SYMBOL(system_call_common); -_ASM_NOKPROBE_SYMBOL(system_call); +_ASM_NOKPROBE_SYMBOL(system_call_exit); /* Save non-volatile GPRs, if not already saved. */ _GLOBAL(save_nvgprs)
--
2.13.1