This stack check implementation leverages the compiler's profiling (gcc -p)

[linux-2.6.git] / arch / i386 / kernel / entry.S

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 3ac7418..dc7ff8f 100644 (file)
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -734,9 +734,62 @@ ENTRY(spurious_interrupt_bug)
        pushl $do_spurious_interrupt_bug
        jmp error_code
 
+#ifdef CONFIG_X86_STACK_CHECK
+ENTRY(mcount)
+       push %eax
+       movl $(THREAD_SIZE - 1),%eax
+       andl %esp,%eax
+       cmpl $STACK_WARN,%eax /* esp reaches into STACK_WARN space */
+       jle 1f
+2:
+       popl %eax
+       ret
+1:
+       lock; btsl $0,stack_overflowed
+       jc 2b
+
+       # switch to overflow stack
+       movl %esp,%eax
+       movl $(stack_overflow_stack + THREAD_SIZE - 4),%esp
+       
+       pushf
+       cli
+       pushl %eax
+
+       # push eip then esp of error for stack_overflow_panic
+       pushl 4(%eax)
+       pushl %eax
+
+       # update the task pointer and cpu in the overflow stack's thread_info.
+       GET_THREAD_INFO_WITH_ESP(%eax)
+       movl TI_task(%eax),%ebx
+       movl %ebx,stack_overflow_stack+TI_task
+       movl TI_cpu(%eax),%ebx
+       movl %ebx,stack_overflow_stack+TI_cpu
+
+       call stack_overflow
+
+       # pop off call arguments
+       addl $8,%esp
+
+       popl %eax
+       popf
+       movl %eax,%esp
+       popl %eax
+       movl $0,stack_overflowed
+       ret
+#warning stack check enabled
+#endif
+
 .previous
 
 .data
+#ifdef CONFIG_X86_STACK_CHECK
+       .globl stack_overflowed
+stack_overflowed:
+       .long 0
+#endif
+
 ENTRY(sys_call_table)
        .long sys_restart_syscall       /* 0 - old "setup()" system call, used for restarting */
        .long sys_exit