Commit-ID:  ecd50f714c421c759354632dd00f70c718c95b10
Gitweb:     http://git.kernel.org/tip/ecd50f714c421c759354632dd00f70c718c95b10
Author:     Masami Hiramatsu <[email protected]>
AuthorDate: Thu, 17 Apr 2014 17:17:40 +0900
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu, 24 Apr 2014 10:03:00 +0200

kprobes, x86: Call exception_enter after kprobes handled

Move exception_enter() call after kprobes handler
is done. Since the exception_enter() involves
many other functions (like printk), it can cause
recursive int3/break loop when kprobes probe such
functions.

Signed-off-by: Masami Hiramatsu <[email protected]>
Reviewed-by: Steven Rostedt <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Seiji Aguchi <[email protected]>
Link: 
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 arch/x86/kernel/traps.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index e5d4a70..ba9abe9 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -327,7 +327,6 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs 
*regs, long error_co
        if (poke_int3_handler(regs))
                return;
 
-       prev_state = exception_enter();
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
        if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
                                SIGTRAP) == NOTIFY_STOP)
@@ -338,6 +337,7 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs 
*regs, long error_co
        if (kprobe_int3_handler(regs))
                return;
 #endif
+       prev_state = exception_enter();
 
        if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
                        SIGTRAP) == NOTIFY_STOP)
@@ -415,8 +415,6 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, 
long error_code)
        unsigned long dr6;
        int si_code;
 
-       prev_state = exception_enter();
-
        get_debugreg(dr6, 6);
 
        /* Filter out all the reserved bits which are preset to 1 */
@@ -449,6 +447,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, 
long error_code)
        if (kprobe_debug_handler(regs))
                goto exit;
 #endif
+       prev_state = exception_enter();
 
        if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
                                                        SIGTRAP) == NOTIFY_STOP)
--
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