From f0a996eeeda214f4293e234df33b29bec003b536 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 10 Aug 2012 12:21:15 -0500 Subject: mips,kgdb: fix recursive page fault with CONFIG_KPROBES This fault was detected using the kgdb test suite on boot and it crashes recursively due to the fact that CONFIG_KPROBES on mips adds an extra die notifier in the page fault handler. The crash signature looks like this: kgdbts:RUN bad memory access test KGDB: re-enter exception: ALL breakpoints killed Call Trace: [<807b7548>] dump_stack+0x20/0x54 [<807b7548>] dump_stack+0x20/0x54 The fix for now is to have kgdb return immediately if the fault type is DIE_PAGE_FAULT and allow the kprobe code to decide what is supposed to happen. Cc: Masami Hiramatsu Cc: David S. Miller Cc: Signed-off-by: Jason Wessel --- arch/mips/kernel/kgdb.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch') diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index f4546e97c60..23817a6e32b 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -283,6 +283,15 @@ static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd, struct pt_regs *regs = args->regs; int trap = (regs->cp0_cause & 0x7c) >> 2; +#ifdef CONFIG_KPROBES + /* + * Return immediately if the kprobes fault notifier has set + * DIE_PAGE_FAULT. + */ + if (cmd == DIE_PAGE_FAULT) + return NOTIFY_DONE; +#endif /* CONFIG_KPROBES */ + /* Userspace events, ignore. */ if (user_mode(regs)) return NOTIFY_DONE; -- cgit v1.2.3-18-g5258 From 42c12213141d7c88e8f649b4bacd19ba14577658 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Wed, 8 Aug 2012 21:12:19 -0500 Subject: kgdb,x86: fix warning about unused variable When compiling without CONFIG_DEBUG_RODATA the following compiler warning is generated: arch/x86/kernel/kgdb.c: In function 'kgdb_arch_set_breakpoint': arch/x86/kernel/kgdb.c:749: warning: unused variable 'opc' The variable instantiation needs to be inside the #ifdef to make the warning go away. Reported-by: Thiago Rafael Becker Signed-off-by: Jason Wessel --- arch/x86/kernel/kgdb.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch') diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 3f61904365c..836f8322960 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -746,7 +746,9 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) { int err; +#ifdef CONFIG_DEBUG_RODATA char opc[BREAK_INSTR_SIZE]; +#endif /* CONFIG_DEBUG_RODATA */ bpt->type = BP_BREAKPOINT; err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, -- cgit v1.2.3-18-g5258