Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 3dc26f9..a224b5a 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
@@ -69,15 +70,6 @@
}
}
-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;
@@ -197,12 +189,6 @@
}
#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)
{
@@ -213,7 +199,7 @@
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;
@@ -221,7 +207,7 @@
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;
@@ -245,14 +231,6 @@
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;
@@ -320,10 +298,14 @@
}
/* Get the next frame pointer: */
- if (state->regs)
+ if (state->next_bp) {
+ next_bp = state->next_bp;
+ state->next_bp = NULL;
+ } else if (state->regs) {
next_bp = (unsigned long *)state->regs->bp;
- else
+ } else {
next_bp = (unsigned long *)READ_ONCE_TASK_STACK(state->task, *state->bp);
+ }
/* Move to the next frame if it's safe: */
if (!update_stack_state(state, next_bp))
@@ -398,6 +380,20 @@
bp = get_frame_pointer(task, regs);
+ /*
+ * If we crash with IP==0, the last successfully executed instruction
+ * was probably an indirect function call with a NULL function pointer.
+ * That means that SP points into the middle of an incomplete frame:
+ * *SP is a return pointer, and *(SP-sizeof(unsigned long)) is where we
+ * would have written a frame pointer if we hadn't crashed.
+ * 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 *)regs->sp >= first_frame) {
+ state->next_bp = bp;
+ bp = ((unsigned long *)regs->sp) - 1;
+ }
+
/* Initialize stack info and make sure the frame data is accessible: */
get_stack_info(bp, state->task, &state->stack_info,
&state->stack_mask);
@@ -410,7 +406,7 @@
*/
while (!unwind_done(state) &&
(!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
- state->bp < first_frame))
+ (state->next_bp == NULL && state->bp < first_frame)))
unwind_next_frame(state);
}
EXPORT_SYMBOL_GPL(__unwind_start);