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Subject[PATCH 13/14] x86/unwind/orc: Add more unwinder warnings
Date
Make sure warnings are displayed for all error scenarios (except when
encountering an empty unwind hint).

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kernel/unwind_orc.c | 29 ++++++++++++++++++++++++-----
1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 0ebc11a8bb45..4118013a574a 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -450,8 +450,15 @@ bool unwind_next_frame(struct unwind_state *state)

/* End-of-stack check for kernel threads: */
if (orc->sp_reg == ORC_REG_UNDEFINED) {
- if (!orc->end)
+ if (!orc->end) {
+ /*
+ * This is reported as an error for the caller, but
+ * otherwise it isn't worth warning about. In theory
+ * it can only happen when hitting UNWIND_HINT_EMPTY in
+ * entry code, close to a kernel exit point.
+ */
goto err;
+ }

goto the_end;
}
@@ -515,8 +522,11 @@ bool unwind_next_frame(struct unwind_state *state)
}

if (indirect) {
- if (!deref_stack_reg(state, sp, &sp))
+ if (!deref_stack_reg(state, sp, &sp)) {
+ orc_warn_current("can't access indirect SP at %pB\n",
+ (void *)state->ip);
goto err;
+ }
}

/* Find IP, SP and possibly regs: */
@@ -524,8 +534,11 @@ bool unwind_next_frame(struct unwind_state *state)
case ORC_TYPE_CALL:
ip_p = sp - sizeof(long);

- if (!deref_stack_reg(state, ip_p, &state->ip))
+ if (!deref_stack_reg(state, ip_p, &state->ip)) {
+ orc_warn_current("can't access call return IP (0x%lx) at %pB\n",
+ ip_p, (void *)orig_ip);
goto err;
+ }

state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
state->ip, (void *)ip_p);
@@ -577,13 +590,19 @@ bool unwind_next_frame(struct unwind_state *state)
break;

case ORC_REG_PREV_SP:
- if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp))
+ if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp)) {
+ orc_warn_current("can't access BP (from SP) at %pB\n",
+ (void *)orig_ip);
goto err;
+ }
break;

case ORC_REG_BP:
- if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp))
+ if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp)) {
+ orc_warn_current("can't access BP at %pB\n",
+ (void *)orig_ip);
goto err;
+ }
break;

default:
--
2.21.1
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