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authorAndi Kleen <ak@suse.de>2006-10-05 18:47:22 +0200
committerAndi Kleen <andi@basil.nowhere.org>2006-10-05 18:47:22 +0200
commit51ec28e1b2cb267a09a0b8eac1ccf8d61b7268bf (patch)
tree4686d439a49b98b98fc5048641ddfb50db3fbcd6
parentf015c6c4d733f68cbc1c5d231bb158abaa5c9606 (diff)
downloadop-kernel-dev-51ec28e1b2cb267a09a0b8eac1ccf8d61b7268bf.zip
op-kernel-dev-51ec28e1b2cb267a09a0b8eac1ccf8d61b7268bf.tar.gz
[PATCH] x86: Terminate the kernel stacks for the unwinder
Always make sure RIP/EIP is 0 in the registers stored on the top of the stack of a kernel thread. This makes sure the unwinder code won't try a fallback but knows the stack has ended. AK: this patch is a bit mysterious. in theory they should be terminated anyways, but it seems to fix at least one crash. Anyways double termination probably doesn't hurt. Signed-off-by: Andi Kleen <ak@suse.de>
-rw-r--r--arch/i386/kernel/process.c6
-rw-r--r--arch/x86_64/kernel/entry.S5
2 files changed, 10 insertions, 1 deletions
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index dad02a9..b0a0780 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -328,6 +328,7 @@ extern void kernel_thread_helper(void);
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
struct pt_regs regs;
+ int err;
memset(&regs, 0, sizeof(regs));
@@ -342,7 +343,10 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
/* Ok, create the new process.. */
- return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
+ err = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
+ if (err == 0) /* terminate kernel stack */
+ task_pt_regs(current)->eip = 0;
+ return err;
}
EXPORT_SYMBOL(kernel_thread);
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index b8285cf..ab9b2c4 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -978,6 +978,11 @@ ENTRY(kernel_thread)
call do_fork
movq %rax,RAX(%rsp)
xorl %edi,%edi
+ test %rax,%rax
+ jnz 1f
+ /* terminate stack in child */
+ movq %rdi,RIP(%rsp)
+1:
/*
* It isn't worth to check for reschedule here,
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