Commit 98272ed0 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86: use kernel_stack_pointer() in kprobes.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.

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
parent 5ca6c0ca

arch/x86/kernel/kprobes.c

+1 −13
Original line number Original line Diff line number Diff line
@@ -60,19 +60,7 @@ void jprobe_return_end(void); 
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;

DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;

DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);

DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);





#ifdef CONFIG_X86_64

#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))

#define stack_addr(regs) ((unsigned long *)regs->sp)

#else

/*

 * "&regs->sp" looks wrong, but it's correct for x86_32.  x86_32 CPUs

 * don't save the ss and esp registers if the CPU is already in kernel

 * mode when it traps.  So for kprobes, regs->sp and regs->ss are not

 * the [nonexistent] saved stack pointer and ss register, but rather

 * the top 8 bytes of the pre-int3 stack.  So &regs->sp happens to

 * point to the top of the pre-int3 stack.

 */

#define stack_addr(regs) ((unsigned long *)&regs->sp)

#endif





#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\

#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\

	(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \

	(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \

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