[Crash-utility] [PATCH v1 3/5] x86_64: Add gdb multi-stack unwind support
Whenever extra stack is found, a user_regs structure is allocated and
regs value copied there. Later the values will be retrived by
get_current_task_reg() by given the thread's tid, aka the index of
stack.
Co-developed-by: Alexey Makhalov <alexey.makhalov(a)broadcom.com>
Co-developed-by: Tao Liu <ltao(a)redhat.com>
Signed-off-by: Tao Liu <ltao(a)redhat.com>
---
x86_64.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 51 insertions(+), 10 deletions(-)
diff --git a/x86_64.c b/x86_64.c
index e544be8..ca745a6 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -3551,6 +3551,7 @@ x86_64_low_budget_back_trace_cmd(struct bt_info *bt_in)
irq_eframe = 0;
last_process_stack_eframe = 0;
bt->call_target = NULL;
+ extra_stacks_idx = 0;
rsp = bt->stkptr;
ms = machdep->machspec;
@@ -4159,6 +4160,7 @@ x86_64_dwarf_back_trace_cmd(struct bt_info *bt_in)
last_process_stack_eframe = 0;
bt->call_target = NULL;
bt->bptr = 0;
+ extra_stacks_idx = 0;
rsp = bt->stkptr;
if (!rsp) {
error(INFO, "cannot determine starting stack pointer\n");
@@ -4546,6 +4548,9 @@ x86_64_back_trace(struct gnu_request *req, struct bt_info *bt)
*
*/
+#define SET_REG_BITMAP(REGMAP, TYPE, MEMBER) \
+ SET_BIT(REGMAP, REG_SEQ(TYPE, MEMBER))
+
long
x86_64_exception_frame(ulong flags, ulong kvaddr, char *local,
struct bt_info *bt, FILE *ofp)
@@ -4799,6 +4804,22 @@ x86_64_exception_frame(ulong flags, ulong kvaddr, char *local,
} else if (machdep->flags & ORC)
bt->bptr = rbp;
+ /*
+ * Preserve registers set for each additional in-kernel stack
+ */
+ if (!(cs & 3) && verified && flags & EFRAME_PRINT &&
+ extra_stacks_idx < MAX_EXCEPTION_STACKS) {
+ if (!extra_stacks_regs[extra_stacks_idx]) {
+ extra_stacks_regs[extra_stacks_idx] = (struct user_regs_bitmap_struct *)
+ GETBUF(sizeof(struct user_regs_bitmap_struct *));
+ }
+ memcpy(&extra_stacks_regs[extra_stacks_idx]->ur,
+ pt_regs_buf, SIZE(pt_regs));
+ for (int i = 0; i < SIZE(pt_regs)/sizeof(long); i++)
+ SET_BIT(extra_stacks_regs[extra_stacks_idx]->bitmap, i);
+ gdb_add_substack(extra_stacks_idx++);
+ }
+
if (kvaddr)
FREEBUF(pt_regs_buf);
@@ -5002,9 +5023,6 @@ get_reg_from_inactive_task_frame(struct bt_info *bt, char
*reg_name,
return reg_value;
}
-#define SET_REG_BITMAP(REGMAP, TYPE, MEMBER) \
- SET_BIT(REGMAP, REG_SEQ(TYPE, MEMBER))
-
/*
* Get a stack frame combination of pc and ra from the most relevent spot.
*/
@@ -5092,11 +5110,22 @@ x86_64_get_stack_frame(struct bt_info *bt, ulong *pcp, ulong
*spp)
* ip and sp in the end of the function.
*/
if (bt->flags & BT_DUMPFILE_SEARCH) {
- FREEBUF(ur_bitmap);
- bt->need_free = FALSE;
*pcp = pcp_save;
*spp = spp_save;
- return x86_64_get_dumpfile_stack_frame(bt, pcp, spp);
+ /*
+ * pcp/spp_save is read from elf notes, for panic
+ * task, we'll continue to use the original elf
+ * notes to get regs; for other active tasks,
+ * we'll update the sp/ip into our own ur_bitmap.
+ */
+ x86_64_get_dumpfile_stack_frame(bt, pcp, spp);
+ if (tt->panic_task == bt->task) {
+ FREEBUF(ur_bitmap);
+ bt->need_free = FALSE;
+ return;
+ } else {
+ sp = *spp;
+ }
}
}
} else {
@@ -5106,11 +5135,16 @@ x86_64_get_stack_frame(struct bt_info *bt, ulong *pcp, ulong
*spp)
SET_REG_BITMAP(ur_bitmap->bitmap, x86_64_user_regs_struct, bp);
} else {
if (bt->flags & BT_DUMPFILE_SEARCH) {
- FREEBUF(ur_bitmap);
- bt->need_free = FALSE;
*pcp = pcp_save;
*spp = spp_save;
- return x86_64_get_dumpfile_stack_frame(bt, pcp, spp);
+ x86_64_get_dumpfile_stack_frame(bt, pcp, spp);
+ if (tt->panic_task == bt->task) {
+ FREEBUF(ur_bitmap);
+ bt->need_free = FALSE;
+ return;
+ } else {
+ sp = *spp;
+ }
}
}
}
@@ -9256,6 +9290,12 @@ x86_64_get_current_task_reg(int regno, const char *name,
if (!tc)
return FALSE;
+ /* Non zero stack ID, use extra stacks regs */
+ if (sid && sid <= extra_stacks_idx) {
+ ur_bitmap = extra_stacks_regs[sid - 1];
+ goto get_sub;
+ }
+
/*
* Task is active, grab CPU's registers
*/
@@ -9280,6 +9320,7 @@ x86_64_get_current_task_reg(int regno, const char *name,
}
/* Get subset registers from stack frame*/
+get_sub:
switch (regno) {
CHECK_REG_CASE(RAX, ax);
CHECK_REG_CASE(RBX, bx);
@@ -9341,7 +9382,7 @@ get_all:
COPY_REG_CASE(ORIG_RAX, orig_ax);
}
- if (bt_info.need_free) {
+ if (!sid && bt_info.need_free) {
FREEBUF(ur_bitmap);
bt_info.need_free = FALSE;
}
--
2.47.0