Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 asm updates from Ingo Molnar:
 "Most of the changes relate to Peter Zijlstra's cleanup of ptregs
  handling, in particular the i386 part is now much simplified and
  standardized - no more partial ptregs stack frames via the esp/ss
  oddity. This simplifies ftrace, kprobes, the unwinder, ptrace, kdump
  and kgdb.

  There's also a CR4 hardening enhancements by Kees Cook, to make the
  generic platform functions such as native_write_cr4() less useful as
  ROP gadgets that disable SMEP/SMAP. Also protect the WP bit of CR0
  against similar attacks.

  The rest is smaller cleanups/fixes"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/alternatives: Add int3_emulate_call() selftest
  x86/stackframe/32: Allow int3_emulate_push()
  x86/stackframe/32: Provide consistent pt_regs
  x86/stackframe, x86/ftrace: Add pt_regs frame annotations
  x86/stackframe, x86/kprobes: Fix frame pointer annotations
  x86/stackframe: Move ENCODE_FRAME_POINTER to asm/frame.h
  x86/entry/32: Clean up return from interrupt preemption path
  x86/asm: Pin sensitive CR0 bits
  x86/asm: Pin sensitive CR4 bits
  Documentation/x86: Fix path to entry_32.S
  x86/asm: Remove unused TASK_TI_flags from asm-offsets.c

1 files changed, 4 insertions, 28 deletions

diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 6106760de716..a224b5ab103f 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -70,15 +70,6 @@ static void unwind_dump(struct unwind_state *state)
 	}
 }
 
-static size_t regs_size(struct pt_regs *regs)
-{
-	/* x86_32 regs from kernel mode are two words shorter: */
-	if (IS_ENABLED(CONFIG_X86_32) && !user_mode(regs))
-		return sizeof(*regs) - 2*sizeof(long);
-
-	return sizeof(*regs);
-}
-
 static bool in_entry_code(unsigned long ip)
 {
 	char *addr = (char *)ip;
@@ -198,12 +189,6 @@ static struct pt_regs *decode_frame_pointer(unsigned long *bp)
 }
 #endif
 
-#ifdef CONFIG_X86_32
-#define KERNEL_REGS_SIZE (sizeof(struct pt_regs) - 2*sizeof(long))
-#else
-#define KERNEL_REGS_SIZE (sizeof(struct pt_regs))
-#endif
-
 static bool update_stack_state(struct unwind_state *state,
 			       unsigned long *next_bp)
 {
@@ -214,7 +199,7 @@ static bool update_stack_state(struct unwind_state *state,
 	size_t len;
 
 	if (state->regs)
-		prev_frame_end = (void *)state->regs + regs_size(state->regs);
+		prev_frame_end = (void *)state->regs + sizeof(*state->regs);
 	else
 		prev_frame_end = (void *)state->bp + FRAME_HEADER_SIZE;
 
@@ -222,7 +207,7 @@ static bool update_stack_state(struct unwind_state *state,
 	regs = decode_frame_pointer(next_bp);
 	if (regs) {
 		frame = (unsigned long *)regs;
-		len = KERNEL_REGS_SIZE;
+		len = sizeof(*regs);
 		state->got_irq = true;
 	} else {
 		frame = next_bp;
@@ -246,14 +231,6 @@ static bool update_stack_state(struct unwind_state *state,
 	    frame < prev_frame_end)
 		return false;
 
-	/*
-	 * On 32-bit with user mode regs, make sure the last two regs are safe
-	 * to access:
-	 */
-	if (IS_ENABLED(CONFIG_X86_32) && regs && user_mode(regs) &&
-	    !on_stack(info, frame, len + 2*sizeof(long)))
-		return false;
-
 	/* Move state to the next frame: */
 	if (regs) {
 		state->regs = regs;
@@ -412,10 +389,9 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 	 * Pretend that the frame is complete and that BP points to it, but save
 	 * the real BP so that we can use it when looking for the next frame.
 	 */
-	if (regs && regs->ip == 0 &&
-	    (unsigned long *)kernel_stack_pointer(regs) >= first_frame) {
+	if (regs && regs->ip == 0 && (unsigned long *)regs->sp >= first_frame) {
 		state->next_bp = bp;
-		bp = ((unsigned long *)kernel_stack_pointer(regs)) - 1;
+		bp = ((unsigned long *)regs->sp) - 1;
 	}
 
 	/* Initialize stack info and make sure the frame data is accessible: */