[PATCH] x86_64: Allow nesting of int3 by default for kprobes

This unbreaks recursive kprobes which didn't work anymore
due to an earlier patch which converted the debug entry point
to use an IST.

This also allows nesting of the debug entry point too.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 7 insertions, 10 deletions

diff --git a/arch/x86_64/kernel/asm-offsets.c b/arch/x86_64/kernel/asm-offsets.c
index cfb4f9cebea..38834bbbae1 100644
--- a/arch/x86_64/kernel/asm-offsets.c
+++ b/arch/x86_64/kernel/asm-offsets.c
@@ -43,6 +43,7 @@ int main(void)
         ENTRY(irqcount);
         ENTRY(cpunumber);
         ENTRY(irqstackptr);
+        ENTRY(data_offset);
         BLANK();
 #undef ENTRY
 #ifdef CONFIG_IA32_EMULATION
@@ -66,8 +67,6 @@ int main(void)
         DEFINE(pbe_orig_address, offsetof(struct pbe, orig_address));
         DEFINE(pbe_next, offsetof(struct pbe, next));
         BLANK();
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
-        DEFINE(DEBUG_IST, DEBUG_STACK);
-#endif
+        DEFINE(TSS_ist, offsetof(struct tss_struct, ist));
         return 0;
 }
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 632fc0f59fc..dbdba56e8fa 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -41,6 +41,7 @@
 #include <asm/unistd.h>
 #include <asm/thread_info.h>
 #include <asm/hw_irq.h>
+#include <asm/page.h>
 
         .code64
 
@@ -674,9 +675,6 @@ ENTRY(spurious_interrupt)
 
         /* error code is on the stack already */
         /* handle NMI like exceptions that can happen everywhere */
-#ifndef DEBUG_IST
-# define DEBUG_IST 0
-#endif
         .macro paranoidentry sym, ist=0
         SAVE_ALL
         cld
@@ -695,11 +693,11 @@ ENTRY(spurious_interrupt)
         movq ORIG_RAX(%rsp),%rsi
         movq $-1,ORIG_RAX(%rsp)
         .if \ist
-        subq    $EXCEPTION_STACK_SIZE, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
+        subq    $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
         .endif
         call \sym
         .if \ist
-        addq    $EXCEPTION_STACK_SIZE, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
+        addq    $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
         .endif
         cli
         .endm
@@ -918,7 +916,7 @@ KPROBE_ENTRY(debug)
         INTR_FRAME
         pushq $0
         CFI_ADJUST_CFA_OFFSET 8         
-        paranoidentry do_debug, DEBUG_IST
+        paranoidentry do_debug, DEBUG_STACK
         jmp paranoid_exit
         CFI_ENDPROC
         .previous .text
@@ -976,7 +974,7 @@ KPROBE_ENTRY(int3)
         INTR_FRAME
         pushq $0
         CFI_ADJUST_CFA_OFFSET 8
-        paranoidentry do_int3, DEBUG_IST
+        paranoidentry do_int3, DEBUG_STACK
         jmp paranoid_exit
         CFI_ENDPROC
         .previous .text