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| author | Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> | 2017-06-29 19:49:18 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-07-03 15:12:01 +0200 |
| commit | 3639d6619c249acf3b8ecc4fd4552486f217dec0 (patch) | |
| tree | c3a58958d2b6cac71919a7190793220424e0bdc9 /arch/powerpc/kernel/entry_64.S | |
| parent | powerpc/64s: Move system_call() symbol to just after setting MSR_EE (diff) | |
| download | linux-3639d6619c249acf3b8ecc4fd4552486f217dec0.tar.xz linux-3639d6619c249acf3b8ecc4fd4552486f217dec0.zip | |
powerpc/64s: Un-blacklist system_call() from kprobes
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.
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index e5cf98d755db..ed45e86673c0 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -188,6 +188,18 @@ system_call: /* label this so stack traces look sane */ andi. r10,r8,MSR_RI beq- unrecov_restore #endif + +/* + * This is a few instructions into the actual syscall exit path (which actually + * starts at .Lsyscall_exit) to cater to kprobe blacklisting and to reduce the + * number of visible symbols for profiling purposes. + * + * We can probe from system_call until this point as MSR_RI is set. But once it + * is cleared below, we won't be able to take a trap. + * + * This is blacklisted from kprobes further below with _ASM_NOKPROBE_SYMBOL(). + */ +system_call_exit: /* * Disable interrupts so current_thread_info()->flags can't change, * and so that we don't get interrupted after loading SRR0/1. @@ -414,7 +426,7 @@ 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) |