Fix a circa 2005 FIXME by implementing a check to ensure that we actually got into the jprobe break handler() due to the trap in jprobe_return().
Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> --- This is v2 of the patch posted previously (*) to change the WARN() to a pr_debug() as suggested by Masami. (*) https://patchwork.ozlabs.org/patch/762670/ - Naveen arch/powerpc/kernel/kprobes.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index db40b13fd3d1..5b26d5202273 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -648,24 +648,22 @@ NOKPROBE_SYMBOL(setjmp_pre_handler); void __used jprobe_return(void) { - asm volatile("trap" ::: "memory"); + asm volatile("jprobe_return_trap:\n" + "trap\n" + ::: "memory"); } NOKPROBE_SYMBOL(jprobe_return); -static void __used jprobe_return_end(void) -{ -} -NOKPROBE_SYMBOL(jprobe_return_end); - int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - /* - * FIXME - we should ideally be validating that we got here 'cos - * of the "trap" in jprobe_return() above, before restoring the - * saved regs... - */ + if (regs->nip != ppc_kallsyms_lookup_name("jprobe_return_trap")) { + pr_debug("longjmp_break_handler NIP (0x%lx) does not match jprobe_return_trap (0x%lx)\n", + regs->nip, ppc_kallsyms_lookup_name("jprobe_return_trap")); + return 0; + } + memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); /* It's OK to start function graph tracing again */ unpause_graph_tracing(); -- 2.14.1
