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unwind: Implement compat fp unwind

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It is important to be able to unwind compat tasks too.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20250924080119.613695709@infradead.org
This commit is contained in:
Peter Zijlstra
2025-09-23 13:27:34 +02:00
parent 5578534e4b
commit c79dd946e3
2 changed files with 30 additions and 11 deletions
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1
include/linux/unwind_user_types.h
View File

@@ -36,6 +36,7 @@ struct unwind_user_state {
unsigned long ip;
unsigned long sp;
unsigned long fp;
unsigned int ws;
enum unwind_user_type current_type;
unsigned int available_types;
bool done;

40
kernel/unwind/user.c
View File

@@ -8,19 +8,32 @@
#include <linux/unwind_user.h>
#include <linux/uaccess.h>
static const struct unwind_user_frame fp_frame = {
ARCH_INIT_USER_FP_FRAME
};
#define for_each_user_frame(state) \
for (unwind_user_start(state); !(state)->done; unwind_user_next(state))
static inline int
get_user_word(unsigned long *word, unsigned long base, int off, unsigned int ws)
{
unsigned long __user *addr = (void __user *)base + off;
#ifdef CONFIG_COMPAT
if (ws == sizeof(int)) {
unsigned int data;
int ret = get_user(data, (unsigned int __user *)addr);
*word = data;
return ret;
}
#endif
return get_user(*word, addr);
}
static int unwind_user_next_fp(struct unwind_user_state *state)
{
const struct unwind_user_frame *frame = &fp_frame;
const struct unwind_user_frame frame = {
ARCH_INIT_USER_FP_FRAME(state->ws)
};
unsigned long cfa, fp, ra;
if (frame->use_fp) {
if (frame.use_fp) {
if (state->fp < state->sp)
return -EINVAL;
cfa = state->fp;
@@ -29,26 +42,26 @@ static int unwind_user_next_fp(struct unwind_user_state *state)
}
/* Get the Canonical Frame Address (CFA) */
cfa += frame->cfa_off;
cfa += frame.cfa_off;
/* stack going in wrong direction? */
if (cfa <= state->sp)
return -EINVAL;
/* Make sure that the address is word aligned */
if (cfa & (sizeof(long) - 1))
if (cfa & (state->ws - 1))
return -EINVAL;
/* Find the Return Address (RA) */
if (get_user(ra, (unsigned long *)(cfa + frame->ra_off)))
if (get_user_word(&ra, cfa, frame.ra_off, state->ws))
return -EINVAL;
if (frame->fp_off && get_user(fp, (unsigned long __user *)(cfa + frame->fp_off)))
if (frame.fp_off && get_user_word(&fp, cfa, frame.fp_off, state->ws))
return -EINVAL;
state->ip = ra;
state->sp = cfa;
if (frame->fp_off)
if (frame.fp_off)
state->fp = fp;
return 0;
}
@@ -100,6 +113,11 @@ static int unwind_user_start(struct unwind_user_state *state)
state->ip = instruction_pointer(regs);
state->sp = user_stack_pointer(regs);
state->fp = frame_pointer(regs);
state->ws = unwind_user_word_size(regs);
if (!state->ws) {
state->done = true;
return -EINVAL;
}
return 0;
}