x86: use kernel_stack_pointer() in dumpstack.c

The way to obtain a kernel-mode stack pointer from a struct pt_regs in
32-bit mode is "subtle": the stack doesn't actually contain the stack
pointer, but rather the location where it would have been marks the
actual previous stack frame.  For clarity, use kernel_stack_pointer()
instead of coding this weirdness explicitly.

Furthermore, user_mode() is only valid when the process is known to
not run in V86 mode.  Use the safer user_mode_vm() instead.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2009-10-12 14:11:09 -07:00
parent def3c5d0a3
commit a343c75d33

View File

@ -268,11 +268,12 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
show_registers(regs);
#ifdef CONFIG_X86_32
sp = (unsigned long) (&regs->sp);
savesegment(ss, ss);
if (user_mode(regs)) {
if (user_mode_vm(regs)) {
sp = regs->sp;
ss = regs->ss & 0xffff;
} else {
sp = kernel_stack_pointer(regs);
savesegment(ss, ss);
}
printk(KERN_EMERG "EIP: [<%08lx>] ", regs->ip);
print_symbol("%s", regs->ip);