The following commit has been merged in the linux branch: commit d1705c558c95418378b11a0be963fe1b3e2fa381 Author: H. Peter Anvin hpa@zytor.com Date: Mon Oct 12 11:32:31 2009 -0700
x86: fix kernel panic on 32 bits when profiling
Latest kernel has a kernel panic in booting on i386 machine when profile=2 setting in cmdline. It is due to 'sp' being incorrect in profile_pc().
BUG: unable to handle kernel NULL pointer dereference at 00000246 IP: [<c01288b6>] profile_pc+0x2a/0x48 *pde = 00000000 Oops: 0000 [#1] SMP
This differs from the original version by Alex Shi in that we use the kernel_stack_pointer() inline already defined in <asm/ptrace.h> for this purpose, instead of #ifdef.
Originally-by: Alex Shi alex.shi@intel.com Cc: "Chen, Tim C" tim.c.chen@intel.com Cc: "Rafael J. Wysocki" rjw@sisk.pl Cc: Andrew Morton akpm@linux-foundation.org Signed-off-by: H. Peter Anvin hpa@zytor.com
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c index dcb00d2..be25734 100644 --- a/arch/x86/kernel/time.c +++ b/arch/x86/kernel/time.c @@ -38,7 +38,8 @@ unsigned long profile_pc(struct pt_regs *regs) #ifdef CONFIG_FRAME_POINTER return *(unsigned long *)(regs->bp + sizeof(long)); #else - unsigned long *sp = (unsigned long *)regs->sp; + unsigned long *sp = + (unsigned long *)kernel_stack_pointer(regs); /* * Return address is either directly at stack pointer * or above a saved flags. Eflags has bits 22-31 zero,