From: H. Peter Anvin Date: Mon, 12 Oct 2009 21:14:10 +0000 (-0700) Subject: x86: use kernel_stack_pointer() in kprobes.c X-Git-Tag: firefly_0821_release~9833^2~3975^2~4 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=98272ed0d2e6509fe7dc571e77956c99bf653bb6;p=firefly-linux-kernel-4.4.55.git 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: H. Peter Anvin Cc: Ananth N Mavinakayanahalli Cc: Anil S Keshavamurthy Cc: "David S. Miller" Cc: Masami Hiramatsu --- diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 7b5169d2b000..2ee4fa3a3f01 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -60,19 +60,7 @@ void jprobe_return_end(void); DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); -#ifdef CONFIG_X86_64 -#define stack_addr(regs) ((unsigned long *)regs->sp) -#else -/* - * "®s->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 ®s->sp happens to - * point to the top of the pre-int3 stack. - */ -#define stack_addr(regs) ((unsigned long *)®s->sp) -#endif +#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs)) #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) | \