hi,
In x86_64 platform, INT1 and INT3 trap stack is IST stack called
DEBUG_STACK, when INT1/INT3 trap happens, system will switch to
DEBUG_STACK by hardware. Current DEBUG_STACK size is 4K, when int1/int3
trap happens, kernel will minus current DEBUG_STACK IST value by 4k. But
if int3/int1 trap is nested, it will destroy other vector's IST stack.
This patch modifies this, it sets DEBUG_STACK size as 8K and allows two
level of nested int1/int3 trap.
Kprobe DEBUG_STACK may be nested, because kprobe hanlder may be probed
by other kprobes. This patch is against 2.6.17-rc3.
Signed-Off-By: bibo, mao <[email protected]>
Thanks
bibo,mao
diff -Nruap 2.6.17-rc3.org/arch/x86_64/kernel/traps.c 2.6.17-rc3/arch/x86_64/kernel/traps.c
--- 2.6.17-rc3.org/arch/x86_64/kernel/traps.c 2006-05-10 12:07:30.000000000 +0800
+++ 2.6.17-rc3/arch/x86_64/kernel/traps.c 2006-05-10 12:18:53.000000000 +0800
@@ -141,50 +141,24 @@ static unsigned long *in_exception_stack
[DOUBLEFAULT_STACK - 1] = "#DF",
[STACKFAULT_STACK - 1] = "#SS",
[MCE_STACK - 1] = "#MC",
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
- [N_EXCEPTION_STACKS ... N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
-#endif
};
- unsigned k;
+ unsigned stack_size, end, k;
for (k = 0; k < N_EXCEPTION_STACKS; k++) {
- unsigned long end;
-
- switch (k + 1) {
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
- case DEBUG_STACK:
- end = cpu_pda(cpu)->debugstack + DEBUG_STKSZ;
- break;
-#endif
- default:
- end = per_cpu(init_tss, cpu).ist[k];
- break;
- }
+ end = per_cpu(init_tss, cpu).ist[k];
if (stack >= end)
continue;
- if (stack >= end - EXCEPTION_STKSZ) {
+ if (k == (DEBUG_STACK - 1))
+ stack_size = DEBUG_STKSZ;
+ else stack_size = EXCEPTION_STKSZ;
+
+ if (stack >= end - stack_size) {
if (*usedp & (1U << k))
break;
*usedp |= 1U << k;
*idp = ids[k];
return (unsigned long *)end;
}
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
- if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
- unsigned j = N_EXCEPTION_STACKS - 1;
-
- do {
- ++j;
- end -= EXCEPTION_STKSZ;
- ids[j][4] = '1' + (j - N_EXCEPTION_STACKS);
- } while (stack < end - EXCEPTION_STKSZ);
- if (*usedp & (1U << j))
- break;
- *usedp |= 1U << j;
- *idp = ids[j];
- return (unsigned long *)end;
- }
-#endif
}
return NULL;
}
diff -Nruap 2.6.17-rc3.org/include/asm-x86_64/page.h 2.6.17-rc3/include/asm-x86_64/page.h
--- 2.6.17-rc3.org/include/asm-x86_64/page.h 2006-05-10 12:07:18.000000000 +0800
+++ 2.6.17-rc3/include/asm-x86_64/page.h 2006-05-10 12:19:24.000000000 +0800
@@ -20,7 +20,7 @@
#define EXCEPTION_STACK_ORDER 0
#define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)
-#define DEBUG_STACK_ORDER EXCEPTION_STACK_ORDER
+#define DEBUG_STACK_ORDER 1
#define DEBUG_STKSZ (PAGE_SIZE << DEBUG_STACK_ORDER)
#define IRQSTACK_ORDER 2
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