diff options
| author | Steven Rostedt <srostedt@redhat.com> | 2011-08-16 13:57:10 (GMT) |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2012-04-28 01:10:44 (GMT) |
| commit | 08d636b6d4fb80647fe8869ea1cd97b2c26a4751 (patch) | |
| tree | eb85c37e3a67e1c21df9b82e2d302d5d1899343a /arch/x86/kernel/traps.c | |
| parent | 438ced1720b584000a9e8a4349d1f6bb7ee3ad6d (diff) | |
| download | linux-08d636b6d4fb80647fe8869ea1cd97b2c26a4751.tar.xz | |
ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine
This method changes x86 to add a breakpoint to the mcount locations
instead of calling stop machine.
Now that iret can be handled by NMIs, we perform the following to
update code:
1) Add a breakpoint to all locations that will be modified
2) Sync all cores
3) Update all locations to be either a nop or call (except breakpoint
op)
4) Sync all cores
5) Remove the breakpoint with the new code.
6) Sync all cores
[
Added updates that Masami suggested:
Use unlikely(modifying_ftrace_code) in int3 trap to keep kprobes efficient.
Don't use NOTIFY_* in ftrace handler in int3 as it is not a notifier.
]
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index ff9281f1..92d5756 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -50,6 +50,7 @@ #include <asm/processor.h> #include <asm/debugreg.h> #include <linux/atomic.h> +#include <asm/ftrace.h> #include <asm/traps.h> #include <asm/desc.h> #include <asm/i387.h> @@ -303,8 +304,13 @@ gp_in_kernel: } /* May run on IST stack. */ -dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code) +dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code) { +#ifdef CONFIG_DYNAMIC_FTRACE + /* ftrace must be first, everything else may cause a recursive crash */ + if (unlikely(modifying_ftrace_code) && ftrace_int3_handler(regs)) + return; +#endif #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP, SIGTRAP) == NOTIFY_STOP) |