summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/unwind_orc.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/unwind_orc.c')
-rw-r--r--arch/x86/kernel/unwind_orc.c88
1 files changed, 37 insertions, 51 deletions
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index a3f973b2c97a..be86a865087a 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -253,22 +253,15 @@ unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
return NULL;
}
-static bool stack_access_ok(struct unwind_state *state, unsigned long addr,
+static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
size_t len)
{
struct stack_info *info = &state->stack_info;
+ void *addr = (void *)_addr;
- /*
- * If the address isn't on the current stack, switch to the next one.
- *
- * We may have to traverse multiple stacks to deal with the possibility
- * that info->next_sp could point to an empty stack and the address
- * could be on a subsequent stack.
- */
- while (!on_stack(info, (void *)addr, len))
- if (get_stack_info(info->next_sp, state->task, info,
- &state->stack_mask))
- return false;
+ if (!on_stack(info, addr, len) &&
+ (get_stack_info(addr, state->task, info, &state->stack_mask)))
+ return false;
return true;
}
@@ -283,42 +276,32 @@ static bool deref_stack_reg(struct unwind_state *state, unsigned long addr,
return true;
}
-#define REGS_SIZE (sizeof(struct pt_regs))
-#define SP_OFFSET (offsetof(struct pt_regs, sp))
-#define IRET_REGS_SIZE (REGS_SIZE - offsetof(struct pt_regs, ip))
-#define IRET_SP_OFFSET (SP_OFFSET - offsetof(struct pt_regs, ip))
-
static bool deref_stack_regs(struct unwind_state *state, unsigned long addr,
- unsigned long *ip, unsigned long *sp, bool full)
+ unsigned long *ip, unsigned long *sp)
{
- size_t regs_size = full ? REGS_SIZE : IRET_REGS_SIZE;
- size_t sp_offset = full ? SP_OFFSET : IRET_SP_OFFSET;
- struct pt_regs *regs = (struct pt_regs *)(addr + regs_size - REGS_SIZE);
-
- if (IS_ENABLED(CONFIG_X86_64)) {
- if (!stack_access_ok(state, addr, regs_size))
- return false;
+ struct pt_regs *regs = (struct pt_regs *)addr;
- *ip = regs->ip;
- *sp = regs->sp;
+ /* x86-32 support will be more complicated due to the &regs->sp hack */
+ BUILD_BUG_ON(IS_ENABLED(CONFIG_X86_32));
- return true;
- }
-
- if (!stack_access_ok(state, addr, sp_offset))
+ if (!stack_access_ok(state, addr, sizeof(struct pt_regs)))
return false;
*ip = regs->ip;
+ *sp = regs->sp;
+ return true;
+}
- if (user_mode(regs)) {
- if (!stack_access_ok(state, addr + sp_offset,
- REGS_SIZE - SP_OFFSET))
- return false;
+static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr,
+ unsigned long *ip, unsigned long *sp)
+{
+ struct pt_regs *regs = (void *)addr - IRET_FRAME_OFFSET;
- *sp = regs->sp;
- } else
- *sp = (unsigned long)&regs->sp;
+ if (!stack_access_ok(state, addr, IRET_FRAME_SIZE))
+ return false;
+ *ip = regs->ip;
+ *sp = regs->sp;
return true;
}
@@ -327,7 +310,6 @@ bool unwind_next_frame(struct unwind_state *state)
unsigned long ip_p, sp, orig_ip, prev_sp = state->sp;
enum stack_type prev_type = state->stack_info.type;
struct orc_entry *orc;
- struct pt_regs *ptregs;
bool indirect = false;
if (unwind_done(state))
@@ -435,7 +417,7 @@ bool unwind_next_frame(struct unwind_state *state)
break;
case ORC_TYPE_REGS:
- if (!deref_stack_regs(state, sp, &state->ip, &state->sp, true)) {
+ if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) {
orc_warn("can't dereference registers at %p for ip %pB\n",
(void *)sp, (void *)orig_ip);
goto done;
@@ -447,20 +429,14 @@ bool unwind_next_frame(struct unwind_state *state)
break;
case ORC_TYPE_REGS_IRET:
- if (!deref_stack_regs(state, sp, &state->ip, &state->sp, false)) {
+ if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) {
orc_warn("can't dereference iret registers at %p for ip %pB\n",
(void *)sp, (void *)orig_ip);
goto done;
}
- ptregs = container_of((void *)sp, struct pt_regs, ip);
- if ((unsigned long)ptregs >= prev_sp &&
- on_stack(&state->stack_info, ptregs, REGS_SIZE)) {
- state->regs = ptregs;
- state->full_regs = false;
- } else
- state->regs = NULL;
-
+ state->regs = (void *)sp - IRET_FRAME_OFFSET;
+ state->full_regs = false;
state->signal = true;
break;
@@ -553,8 +529,18 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
}
if (get_stack_info((unsigned long *)state->sp, state->task,
- &state->stack_info, &state->stack_mask))
- return;
+ &state->stack_info, &state->stack_mask)) {
+ /*
+ * We weren't on a valid stack. It's possible that
+ * we overflowed a valid stack into a guard page.
+ * See if the next page up is valid so that we can
+ * generate some kind of backtrace if this happens.
+ */
+ void *next_page = (void *)PAGE_ALIGN((unsigned long)state->sp);
+ if (get_stack_info(next_page, state->task, &state->stack_info,
+ &state->stack_mask))
+ return;
+ }
/*
* The caller can provide the address of the first frame directly