* [PATCH v2 1/6] LoongArch: Get frame info in unwind_start when regs is not supported
2022-12-29 6:15 [PATCH v2 0/5] LoongArch: Some fix and new features for unwinders Jinyang He
@ 2022-12-29 6:15 ` Jinyang He
2022-12-29 6:15 ` [PATCH v2 2/6] LoongArch: Use correct sp value to get graph addr in unwinder guess Jinyang He
` (3 subsequent siblings)
4 siblings, 0 replies; 9+ messages in thread
From: Jinyang He @ 2022-12-29 6:15 UTC (permalink / raw)
To: Huacai Chen, WANG Xuerui, Qing Zhang
Cc: loongarch, linux-kernel, Steven Rostedt, Masami Hiramatsu, Mark Rutland
At unwind_start, it is better to try to get its frame info even we not
support regs rather than get them outside. So that we can simply use
unwind_{start, next_frame, done} outside.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/loongarch/kernel/process.c | 12 +++---------
arch/loongarch/kernel/unwind_guess.c | 6 ++++++
arch/loongarch/kernel/unwind_prologue.c | 16 +++++++++++++---
3 files changed, 22 insertions(+), 12 deletions(-)
diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
index 502b8b950057..6ef45174ad35 100644
--- a/arch/loongarch/kernel/process.c
+++ b/arch/loongarch/kernel/process.c
@@ -197,20 +197,14 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
unsigned long __get_wchan(struct task_struct *task)
{
- unsigned long pc;
+ unsigned long pc = 0;
struct unwind_state state;
if (!try_get_task_stack(task))
return 0;
- unwind_start(&state, task, NULL);
- state.sp = thread_saved_fp(task);
- get_stack_info(state.sp, state.task, &state.stack_info);
- state.pc = thread_saved_ra(task);
-#ifdef CONFIG_UNWINDER_PROLOGUE
- state.type = UNWINDER_PROLOGUE;
-#endif
- for (; !unwind_done(&state); unwind_next_frame(&state)) {
+ for (unwind_start(&state, task, NULL); !unwind_done(&state);
+ unwind_next_frame(&state)) {
pc = unwind_get_return_address(&state);
if (!pc)
break;
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index e2d2e4f3001f..a1bc7c852000 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -26,6 +26,12 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
if (regs) {
state->sp = regs->regs[3];
state->pc = regs->csr_era;
+ } else if (task == current || task == NULL) {
+ state->sp = (unsigned long)__builtin_frame_address(0);
+ state->pc = (unsigned long)__builtin_return_address(0);
+ } else {
+ state->sp = thread_saved_fp(task);
+ state->pc = thread_saved_ra(task);
}
state->task = task;
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index 0f8d1451ebb8..b8b830b69a48 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -141,12 +141,22 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs)
{
memset(state, 0, sizeof(*state));
+ state->type = UNWINDER_PROLOGUE;
- if (regs && __kernel_text_address(regs->csr_era)) {
- state->pc = regs->csr_era;
+ if (regs) {
state->sp = regs->regs[3];
+ state->pc = regs->csr_era;
state->ra = regs->regs[1];
- state->type = UNWINDER_PROLOGUE;
+ if (!__kernel_text_address(state->pc))
+ state->type = UNWINDER_GUESS;
+ } else if (task == current || task == NULL) {
+ state->sp = (unsigned long)__builtin_frame_address(0);
+ state->pc = (unsigned long)__builtin_return_address(0);
+ state->ra = 0;
+ } else {
+ state->sp = thread_saved_fp(task);
+ state->pc = thread_saved_ra(task);
+ state->ra = 0;
}
state->task = task;
--
2.34.3
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 2/6] LoongArch: Use correct sp value to get graph addr in unwinder guess
2022-12-29 6:15 [PATCH v2 0/5] LoongArch: Some fix and new features for unwinders Jinyang He
2022-12-29 6:15 ` [PATCH v2 1/6] LoongArch: Get frame info in unwind_start when regs is not supported Jinyang He
@ 2022-12-29 6:15 ` Jinyang He
2022-12-29 6:15 ` [PATCH v2 3/6] LoongArch: Adjust PC value when unwind next frame in prologue unwinder Jinyang He
` (2 subsequent siblings)
4 siblings, 0 replies; 9+ messages in thread
From: Jinyang He @ 2022-12-29 6:15 UTC (permalink / raw)
To: Huacai Chen, WANG Xuerui, Qing Zhang
Cc: loongarch, linux-kernel, Steven Rostedt, Masami Hiramatsu, Mark Rutland
The stack frame when function_graph enable like follows,
--------- <- function sp_on_entry
|
|
|
FAKE_RA <- sp_on_entry - sizeof(pt_regs) + PT_R1
|
--------- <- sp_on_entry - sizeof(pt_regs)
So if we want to get the &FAKE_RA we should get sp_on_entry first.
In unwinder_prologue case, we can get the sp_on_entry as state->sp,
because we try to calculate each CFA and the ra saved address.
But in unwinder_guess case, we cannot get it because we do not try
to calculate the CFA. Although LoongArch have not fixed frame, the
$ra is saved at CFA - 8 in most cases, we can try guess, too.
As we store the pc in state, we not need to dereference state->sp, too.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/loongarch/include/asm/ftrace.h | 2 --
arch/loongarch/include/asm/unwind.h | 9 +++++++++
arch/loongarch/kernel/unwind_guess.c | 12 ++++--------
arch/loongarch/kernel/unwind_prologue.c | 22 ++++++----------------
4 files changed, 19 insertions(+), 26 deletions(-)
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 90f9d3399b2a..3418d32d4fc7 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -10,8 +10,6 @@
#define FTRACE_REGS_PLT_IDX 1
#define NR_FTRACE_PLTS 2
-#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
-
#ifdef CONFIG_FUNCTION_TRACER
#define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */
diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index f2b52b9ea93d..6ece48f0ff77 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -7,8 +7,10 @@
#ifndef _ASM_UNWIND_H
#define _ASM_UNWIND_H
+#include <linux/ftrace.h>
#include <linux/sched.h>
+#include <asm/ptrace.h>
#include <asm/stacktrace.h>
enum unwinder_type {
@@ -40,4 +42,11 @@ static inline bool unwind_error(struct unwind_state *state)
return state->error;
}
+#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
+static inline unsigned long unwind_graph_addr(struct unwind_state *state,
+ unsigned long pc, unsigned long cfa)
+{
+ return ftrace_graph_ret_addr(state->task, &state->graph_idx,
+ pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
+}
#endif /* _ASM_UNWIND_H */
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index a1bc7c852000..935d24f8c95c 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -11,10 +11,7 @@ unsigned long unwind_get_return_address(struct unwind_state *state)
{
if (unwind_done(state))
return 0;
- else if (state->first)
- return state->pc;
-
- return *(unsigned long *)(state->sp);
+ return state->pc;
}
EXPORT_SYMBOL_GPL(unwind_get_return_address);
@@ -36,7 +33,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
state->task = task;
state->first = true;
-
+ state->pc = unwind_graph_addr(state, state->pc, state->sp);
get_stack_info(state->sp, state->task, &state->stack_info);
if (!unwind_done(state) && !__kernel_text_address(state->pc))
@@ -60,9 +57,8 @@ bool unwind_next_frame(struct unwind_state *state)
state->sp < info->end;
state->sp += sizeof(unsigned long)) {
addr = *(unsigned long *)(state->sp);
- state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
- addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
- if (__kernel_text_address(addr))
+ state->pc = unwind_graph_addr(state, addr, state->sp + 8);
+ if (__kernel_text_address(state->pc))
return true;
}
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index b8b830b69a48..3fbb9c65d64e 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -21,16 +21,9 @@ static inline void unwind_state_fixup(struct unwind_state *state)
unsigned long unwind_get_return_address(struct unwind_state *state)
{
-
if (unwind_done(state))
return 0;
- else if (state->type)
- return state->pc;
- else if (state->first)
- return state->pc;
-
- return *(unsigned long *)(state->sp);
-
+ return state->pc;
}
EXPORT_SYMBOL_GPL(unwind_get_return_address);
@@ -43,9 +36,8 @@ static bool unwind_by_guess(struct unwind_state *state)
state->sp < info->end;
state->sp += sizeof(unsigned long)) {
addr = *(unsigned long *)(state->sp);
- state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
- addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
- if (__kernel_text_address(addr))
+ state->pc = unwind_graph_addr(state, addr, state->sp + 8);
+ if (__kernel_text_address(state->pc))
return true;
}
@@ -161,7 +153,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
state->task = task;
state->first = true;
-
+ state->pc = unwind_graph_addr(state, state->pc, state->sp);
get_stack_info(state->sp, state->task, &state->stack_info);
if (!unwind_done(state) && !__kernel_text_address(state->pc))
@@ -188,8 +180,7 @@ bool unwind_next_frame(struct unwind_state *state)
case UNWINDER_PROLOGUE:
if (unwind_by_prologue(state)) {
- state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
- state->pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
+ state->pc = unwind_graph_addr(state, state->pc, state->sp);
return true;
}
@@ -204,8 +195,7 @@ bool unwind_next_frame(struct unwind_state *state)
state->first = true;
state->ra = regs->regs[1];
state->sp = regs->regs[3];
- state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
- pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
+ state->pc = pc;
get_stack_info(state->sp, state->task, info);
return true;
--
2.34.3
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 3/6] LoongArch: Adjust PC value when unwind next frame in prologue unwinder
2022-12-29 6:15 [PATCH v2 0/5] LoongArch: Some fix and new features for unwinders Jinyang He
2022-12-29 6:15 ` [PATCH v2 1/6] LoongArch: Get frame info in unwind_start when regs is not supported Jinyang He
2022-12-29 6:15 ` [PATCH v2 2/6] LoongArch: Use correct sp value to get graph addr in unwinder guess Jinyang He
@ 2022-12-29 6:15 ` Jinyang He
2022-12-29 6:15 ` [PATCH v2 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder Jinyang He
2022-12-29 6:15 ` [PATCH v2 5/6] LoongArch: Add generic ex-handler unwind in prologue unwinder Jinyang He
4 siblings, 0 replies; 9+ messages in thread
From: Jinyang He @ 2022-12-29 6:15 UTC (permalink / raw)
To: Huacai Chen, WANG Xuerui, Qing Zhang
Cc: loongarch, linux-kernel, Steven Rostedt, Masami Hiramatsu, Mark Rutland
When state->first is not set, the PC is a return address in the
previous frame. We need to adjust it value in case overflow to the
next symbol.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/loongarch/kernel/unwind_prologue.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index 3fbb9c65d64e..f7994ed05f04 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -48,7 +48,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
{
long frame_ra = -1;
unsigned long frame_size = 0;
- unsigned long size, offset, pc = state->pc;
+ unsigned long size, offset, pc;
struct pt_regs *regs;
struct stack_info *info = &state->stack_info;
union loongarch_instruction *ip, *ip_end;
@@ -70,6 +70,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
return true;
}
+ /* When first is not set, the PC is a return address in the previous frame.
+ * We need to adjust it value in case overflow to the next symbol.
+ */
+ pc = state->pc - (state->first ? 0 : LOONGARCH_INSN_SIZE);
if (!kallsyms_lookup_size_offset(pc, &size, &offset))
return false;
--
2.34.3
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder
2022-12-29 6:15 [PATCH v2 0/5] LoongArch: Some fix and new features for unwinders Jinyang He
` (2 preceding siblings ...)
2022-12-29 6:15 ` [PATCH v2 3/6] LoongArch: Adjust PC value when unwind next frame in prologue unwinder Jinyang He
@ 2022-12-29 6:15 ` Jinyang He
2023-01-01 9:56 ` Huacai Chen
2022-12-29 6:15 ` [PATCH v2 5/6] LoongArch: Add generic ex-handler unwind in prologue unwinder Jinyang He
4 siblings, 1 reply; 9+ messages in thread
From: Jinyang He @ 2022-12-29 6:15 UTC (permalink / raw)
To: Huacai Chen, WANG Xuerui, Qing Zhang
Cc: loongarch, linux-kernel, Steven Rostedt, Masami Hiramatsu, Mark Rutland
The prolugue unwinder rely on symbol info. When PC is not in kernel
text address, it cannot find relative symbol info and it will be broken.
The guess unwinder will be used in this case. And the guess unwinder
codes in prolugue unwinder is redundant. Strip it out and set the
unwinder info in unwind_state.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/loongarch/include/asm/unwind.h | 26 ++++-
arch/loongarch/kernel/Makefile | 3 +-
arch/loongarch/kernel/traps.c | 3 -
arch/loongarch/kernel/unwind.c | 52 +++++++++
arch/loongarch/kernel/unwind_guess.c | 41 ++------
arch/loongarch/kernel/unwind_prologue.c | 133 +++++++++---------------
6 files changed, 132 insertions(+), 126 deletions(-)
create mode 100644 arch/loongarch/kernel/unwind.c
diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index 6ece48f0ff77..4a55fd7b77ad 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -13,20 +13,30 @@
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
-enum unwinder_type {
- UNWINDER_GUESS,
- UNWINDER_PROLOGUE,
-};
+struct unwinder_ops;
struct unwind_state {
- char type; /* UNWINDER_XXX */
struct stack_info stack_info;
struct task_struct *task;
bool first, error, is_ftrace;
int graph_idx;
unsigned long sp, pc, ra;
+ const struct unwinder_ops *ops;
+};
+
+struct unwinder_ops {
+ void (*unwind_start)(struct unwind_state *state,
+ struct task_struct *task, struct pt_regs *regs);
+ bool (*unwind_next_frame)(struct unwind_state *state);
+ unsigned long (*unwind_get_return_address)(struct unwind_state *state);
};
+extern const struct unwinder_ops *default_unwinder;
+extern const struct unwinder_ops unwinder_guess;
+#ifdef CONFIG_UNWINDER_PROLOGUE
+extern const struct unwinder_ops unwinder_prologue;
+#endif
+
void unwind_start(struct unwind_state *state,
struct task_struct *task, struct pt_regs *regs);
bool unwind_next_frame(struct unwind_state *state);
@@ -49,4 +59,10 @@ static inline unsigned long unwind_graph_addr(struct unwind_state *state,
return ftrace_graph_ret_addr(state->task, &state->graph_idx,
pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
}
+
+static inline void unwind_register_unwinder(struct unwind_state *state,
+ const struct unwinder_ops *unwinder)
+{
+ state->ops = unwinder;
+}
#endif /* _ASM_UNWIND_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 7ca65195f7f8..cb6029ea3ea9 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -8,7 +8,7 @@ extra-y := vmlinux.lds
obj-y += head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \
- alternative.o unaligned.o
+ alternative.o unaligned.o unwind.o unwind_guess.o
obj-$(CONFIG_ACPI) += acpi.o
obj-$(CONFIG_EFI) += efi.o
@@ -42,7 +42,6 @@ obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
-obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index 3adc44832205..1ea14f6c18d3 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -72,9 +72,6 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
if (!task)
task = current;
- if (user_mode(regs))
- state.type = UNWINDER_GUESS;
-
printk("%sCall Trace:", loglvl);
for (unwind_start(&state, task, pregs);
!unwind_done(&state); unwind_next_frame(&state)) {
diff --git a/arch/loongarch/kernel/unwind.c b/arch/loongarch/kernel/unwind.c
new file mode 100644
index 000000000000..24d2cf99bfb6
--- /dev/null
+++ b/arch/loongarch/kernel/unwind.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <asm/unwind.h>
+
+#if defined(CONFIG_UNWINDER_GUESS)
+const struct unwinder_ops *default_unwinder = &unwinder_guess;
+#elif defined(CONFIG_UNWINDER_PROLOGUE)
+const struct unwinder_ops *default_unwinder = &unwinder_prologue;
+#endif
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+ if (!state->ops || unwind_done(state))
+ return 0;
+ return state->ops->unwind_get_return_address(state);
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs)
+{
+ memset(state, 0, sizeof(*state));
+ unwind_register_unwinder(state, default_unwinder);
+ if (regs) {
+ state->sp = regs->regs[3];
+ state->pc = regs->csr_era;
+ state->ra = regs->regs[1];
+ } else if (task == current || task == NULL) {
+ state->sp = (unsigned long)__builtin_frame_address(0);
+ state->pc = (unsigned long)__builtin_return_address(0);
+ state->ra = 0;
+ } else {
+ state->sp = thread_saved_fp(task);
+ state->pc = thread_saved_ra(task);
+ state->ra = 0;
+ }
+ state->task = task;
+ get_stack_info(state->sp, state->task, &state->stack_info);
+ state->pc = unwind_graph_addr(state, state->pc, state->sp);
+ state->ops->unwind_start(state, task, regs);
+}
+EXPORT_SYMBOL_GPL(unwind_start);
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+ if (!state->ops || unwind_done(state))
+ return false;
+ return state->ops->unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index 935d24f8c95c..b7ca2b88ac63 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -7,51 +7,23 @@
#include <asm/unwind.h>
-unsigned long unwind_get_return_address(struct unwind_state *state)
+static unsigned long get_return_address(struct unwind_state *state)
{
- if (unwind_done(state))
- return 0;
return state->pc;
}
-EXPORT_SYMBOL_GPL(unwind_get_return_address);
-void unwind_start(struct unwind_state *state, struct task_struct *task,
+static void start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs)
{
- memset(state, 0, sizeof(*state));
-
- if (regs) {
- state->sp = regs->regs[3];
- state->pc = regs->csr_era;
- } else if (task == current || task == NULL) {
- state->sp = (unsigned long)__builtin_frame_address(0);
- state->pc = (unsigned long)__builtin_return_address(0);
- } else {
- state->sp = thread_saved_fp(task);
- state->pc = thread_saved_ra(task);
- }
-
- state->task = task;
- state->first = true;
- state->pc = unwind_graph_addr(state, state->pc, state->sp);
- get_stack_info(state->sp, state->task, &state->stack_info);
-
if (!unwind_done(state) && !__kernel_text_address(state->pc))
unwind_next_frame(state);
}
-EXPORT_SYMBOL_GPL(unwind_start);
-bool unwind_next_frame(struct unwind_state *state)
+static bool next_frame(struct unwind_state *state)
{
struct stack_info *info = &state->stack_info;
unsigned long addr;
- if (unwind_done(state))
- return false;
-
- if (state->first)
- state->first = false;
-
do {
for (state->sp += sizeof(unsigned long);
state->sp < info->end;
@@ -68,4 +40,9 @@ bool unwind_next_frame(struct unwind_state *state)
return false;
}
-EXPORT_SYMBOL_GPL(unwind_next_frame);
+
+const struct unwinder_ops unwinder_guess = {
+ .unwind_start = start,
+ .unwind_next_frame = next_frame,
+ .unwind_get_return_address = get_return_address,
+};
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index f7994ed05f04..beb57ea24da2 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -19,31 +19,19 @@ static inline void unwind_state_fixup(struct unwind_state *state)
#endif
}
-unsigned long unwind_get_return_address(struct unwind_state *state)
+static unsigned long get_return_address(struct unwind_state *state)
{
- if (unwind_done(state))
- return 0;
return state->pc;
}
-EXPORT_SYMBOL_GPL(unwind_get_return_address);
-
-static bool unwind_by_guess(struct unwind_state *state)
-{
- struct stack_info *info = &state->stack_info;
- unsigned long addr;
-
- for (state->sp += sizeof(unsigned long);
- state->sp < info->end;
- state->sp += sizeof(unsigned long)) {
- addr = *(unsigned long *)(state->sp);
- state->pc = unwind_graph_addr(state, addr, state->sp + 8);
- if (__kernel_text_address(state->pc))
- return true;
- }
-
- return false;
-}
+/*
+ * LoongArch function prologue like follows,
+ * [others instructions not use stack var]
+ * addi.d sp, sp, -imm
+ * st.d xx, sp, offset <- save callee saved regs and
+ * st.d yy, sp, offset save ra if function is nest.
+ * [others instructions]
+ */
static bool unwind_by_prologue(struct unwind_state *state)
{
long frame_ra = -1;
@@ -89,6 +77,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
ip++;
}
+ /*
+ * Not find stack alloc action, PC may be in a leaf function. Only the
+ * first being true is reasonable, otherwise indicate analysis is broken.
+ */
if (!frame_size) {
if (state->first)
goto first;
@@ -106,6 +98,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
ip++;
}
+ /* Not find save $ra action, PC may be in a leaf function, too. */
if (frame_ra < 0) {
if (state->first) {
state->sp = state->sp + frame_size;
@@ -114,96 +107,63 @@ static bool unwind_by_prologue(struct unwind_state *state)
return false;
}
- if (state->first)
- state->first = false;
-
state->pc = *(unsigned long *)(state->sp + frame_ra);
state->sp = state->sp + frame_size;
goto out;
first:
- state->first = false;
- if (state->pc == state->ra)
- return false;
-
state->pc = state->ra;
out:
+ state->first = false;
unwind_state_fixup(state);
return !!__kernel_text_address(state->pc);
}
-void unwind_start(struct unwind_state *state, struct task_struct *task,
+static void start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs)
{
- memset(state, 0, sizeof(*state));
- state->type = UNWINDER_PROLOGUE;
-
- if (regs) {
- state->sp = regs->regs[3];
- state->pc = regs->csr_era;
- state->ra = regs->regs[1];
- if (!__kernel_text_address(state->pc))
- state->type = UNWINDER_GUESS;
- } else if (task == current || task == NULL) {
- state->sp = (unsigned long)__builtin_frame_address(0);
- state->pc = (unsigned long)__builtin_return_address(0);
- state->ra = 0;
- } else {
- state->sp = thread_saved_fp(task);
- state->pc = thread_saved_ra(task);
- state->ra = 0;
- }
-
- state->task = task;
state->first = true;
- state->pc = unwind_graph_addr(state, state->pc, state->sp);
- get_stack_info(state->sp, state->task, &state->stack_info);
- if (!unwind_done(state) && !__kernel_text_address(state->pc))
- unwind_next_frame(state);
+ /*
+ * The current PC is not kernel text address, we cannot find its
+ * relative symbol. Thus, prologue analysis will be broken. Luckly,
+ * we can use the guess unwinder.
+ */
+ if (!__kernel_text_address(state->pc)) {
+ unwind_register_unwinder(state, &unwinder_guess);
+ if (!unwind_done(state))
+ unwind_next_frame(state);
+ }
}
-EXPORT_SYMBOL_GPL(unwind_start);
-bool unwind_next_frame(struct unwind_state *state)
+static bool next_frame(struct unwind_state *state)
{
struct stack_info *info = &state->stack_info;
struct pt_regs *regs;
unsigned long pc;
- if (unwind_done(state))
- return false;
-
do {
- switch (state->type) {
- case UNWINDER_GUESS:
- state->first = false;
- if (unwind_by_guess(state))
- return true;
- break;
-
- case UNWINDER_PROLOGUE:
- if (unwind_by_prologue(state)) {
- state->pc = unwind_graph_addr(state, state->pc, state->sp);
- return true;
- }
+ if (unwind_by_prologue(state)) {
+ state->pc = unwind_graph_addr(state, state->pc, state->sp);
+ return true;
+ }
- if (info->type == STACK_TYPE_IRQ &&
- info->end == state->sp) {
- regs = (struct pt_regs *)info->next_sp;
- pc = regs->csr_era;
+ if (info->type == STACK_TYPE_IRQ &&
+ info->end == state->sp) {
+ regs = (struct pt_regs *)info->next_sp;
+ pc = regs->csr_era;
- if (user_mode(regs) || !__kernel_text_address(pc))
- return false;
+ if (user_mode(regs) || !__kernel_text_address(pc))
+ return false;
- state->first = true;
- state->ra = regs->regs[1];
- state->sp = regs->regs[3];
- state->pc = pc;
- get_stack_info(state->sp, state->task, info);
+ state->first = true;
+ state->ra = regs->regs[1];
+ state->sp = regs->regs[3];
+ state->pc = pc;
+ get_stack_info(state->sp, state->task, info);
- return true;
- }
+ return true;
}
state->sp = info->next_sp;
@@ -212,4 +172,9 @@ bool unwind_next_frame(struct unwind_state *state)
return false;
}
-EXPORT_SYMBOL_GPL(unwind_next_frame);
+
+const struct unwinder_ops unwinder_prologue = {
+ .unwind_start = start,
+ .unwind_next_frame = next_frame,
+ .unwind_get_return_address = get_return_address,
+};
--
2.34.3
^ permalink raw reply related [flat|nested] 9+ messages in thread* Re: [PATCH v2 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder
2022-12-29 6:15 ` [PATCH v2 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder Jinyang He
@ 2023-01-01 9:56 ` Huacai Chen
2023-01-03 8:40 ` Jinyang He
0 siblings, 1 reply; 9+ messages in thread
From: Huacai Chen @ 2023-01-01 9:56 UTC (permalink / raw)
To: Jinyang He
Cc: WANG Xuerui, Qing Zhang, loongarch, linux-kernel, Steven Rostedt,
Masami Hiramatsu, Mark Rutland
Hi, Jinyang,
On Thu, Dec 29, 2022 at 2:15 PM Jinyang He <hejinyang@loongson.cn> wrote:
>
> The prolugue unwinder rely on symbol info. When PC is not in kernel
> text address, it cannot find relative symbol info and it will be broken.
> The guess unwinder will be used in this case. And the guess unwinder
> codes in prolugue unwinder is redundant. Strip it out and set the
> unwinder info in unwind_state.
>
> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
> ---
> arch/loongarch/include/asm/unwind.h | 26 ++++-
> arch/loongarch/kernel/Makefile | 3 +-
> arch/loongarch/kernel/traps.c | 3 -
> arch/loongarch/kernel/unwind.c | 52 +++++++++
> arch/loongarch/kernel/unwind_guess.c | 41 ++------
> arch/loongarch/kernel/unwind_prologue.c | 133 +++++++++---------------
> 6 files changed, 132 insertions(+), 126 deletions(-)
> create mode 100644 arch/loongarch/kernel/unwind.c
>
> diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
> index 6ece48f0ff77..4a55fd7b77ad 100644
> --- a/arch/loongarch/include/asm/unwind.h
> +++ b/arch/loongarch/include/asm/unwind.h
> @@ -13,20 +13,30 @@
> #include <asm/ptrace.h>
> #include <asm/stacktrace.h>
>
> -enum unwinder_type {
> - UNWINDER_GUESS,
> - UNWINDER_PROLOGUE,
> -};
> +struct unwinder_ops;
>
> struct unwind_state {
> - char type; /* UNWINDER_XXX */
> struct stack_info stack_info;
> struct task_struct *task;
> bool first, error, is_ftrace;
> int graph_idx;
> unsigned long sp, pc, ra;
> + const struct unwinder_ops *ops;
> +};
> +
> +struct unwinder_ops {
> + void (*unwind_start)(struct unwind_state *state,
> + struct task_struct *task, struct pt_regs *regs);
> + bool (*unwind_next_frame)(struct unwind_state *state);
> + unsigned long (*unwind_get_return_address)(struct unwind_state *state);
> };
>
> +extern const struct unwinder_ops *default_unwinder;
> +extern const struct unwinder_ops unwinder_guess;
> +#ifdef CONFIG_UNWINDER_PROLOGUE
> +extern const struct unwinder_ops unwinder_prologue;
> +#endif
> +
> void unwind_start(struct unwind_state *state,
> struct task_struct *task, struct pt_regs *regs);
> bool unwind_next_frame(struct unwind_state *state);
> @@ -49,4 +59,10 @@ static inline unsigned long unwind_graph_addr(struct unwind_state *state,
> return ftrace_graph_ret_addr(state->task, &state->graph_idx,
> pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
> }
> +
> +static inline void unwind_register_unwinder(struct unwind_state *state,
> + const struct unwinder_ops *unwinder)
> +{
> + state->ops = unwinder;
> +}
> #endif /* _ASM_UNWIND_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 7ca65195f7f8..cb6029ea3ea9 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -8,7 +8,7 @@ extra-y := vmlinux.lds
> obj-y += head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
> traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
> elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \
> - alternative.o unaligned.o
> + alternative.o unaligned.o unwind.o unwind_guess.o
>
> obj-$(CONFIG_ACPI) += acpi.o
> obj-$(CONFIG_EFI) += efi.o
> @@ -42,7 +42,6 @@ obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o
> obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
> obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
>
> -obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
We do have CONFIG_UNWINDER_GUESS and I don't like to build guess
unwinder unconditionally, maybe we can refactor it to make the
unwinder still user selectable.
Huacai
>
> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> index 3adc44832205..1ea14f6c18d3 100644
> --- a/arch/loongarch/kernel/traps.c
> +++ b/arch/loongarch/kernel/traps.c
> @@ -72,9 +72,6 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
> if (!task)
> task = current;
>
> - if (user_mode(regs))
> - state.type = UNWINDER_GUESS;
> -
> printk("%sCall Trace:", loglvl);
> for (unwind_start(&state, task, pregs);
> !unwind_done(&state); unwind_next_frame(&state)) {
> diff --git a/arch/loongarch/kernel/unwind.c b/arch/loongarch/kernel/unwind.c
> new file mode 100644
> index 000000000000..24d2cf99bfb6
> --- /dev/null
> +++ b/arch/loongarch/kernel/unwind.c
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +#include <asm/unwind.h>
> +
> +#if defined(CONFIG_UNWINDER_GUESS)
> +const struct unwinder_ops *default_unwinder = &unwinder_guess;
> +#elif defined(CONFIG_UNWINDER_PROLOGUE)
> +const struct unwinder_ops *default_unwinder = &unwinder_prologue;
> +#endif
> +
> +unsigned long unwind_get_return_address(struct unwind_state *state)
> +{
> + if (!state->ops || unwind_done(state))
> + return 0;
> + return state->ops->unwind_get_return_address(state);
> +}
> +EXPORT_SYMBOL_GPL(unwind_get_return_address);
> +
> +void unwind_start(struct unwind_state *state, struct task_struct *task,
> + struct pt_regs *regs)
> +{
> + memset(state, 0, sizeof(*state));
> + unwind_register_unwinder(state, default_unwinder);
> + if (regs) {
> + state->sp = regs->regs[3];
> + state->pc = regs->csr_era;
> + state->ra = regs->regs[1];
> + } else if (task == current || task == NULL) {
> + state->sp = (unsigned long)__builtin_frame_address(0);
> + state->pc = (unsigned long)__builtin_return_address(0);
> + state->ra = 0;
> + } else {
> + state->sp = thread_saved_fp(task);
> + state->pc = thread_saved_ra(task);
> + state->ra = 0;
> + }
> + state->task = task;
> + get_stack_info(state->sp, state->task, &state->stack_info);
> + state->pc = unwind_graph_addr(state, state->pc, state->sp);
> + state->ops->unwind_start(state, task, regs);
> +}
> +EXPORT_SYMBOL_GPL(unwind_start);
> +
> +bool unwind_next_frame(struct unwind_state *state)
> +{
> + if (!state->ops || unwind_done(state))
> + return false;
> + return state->ops->unwind_next_frame(state);
> +}
> +EXPORT_SYMBOL_GPL(unwind_next_frame);
> diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
> index 935d24f8c95c..b7ca2b88ac63 100644
> --- a/arch/loongarch/kernel/unwind_guess.c
> +++ b/arch/loongarch/kernel/unwind_guess.c
> @@ -7,51 +7,23 @@
>
> #include <asm/unwind.h>
>
> -unsigned long unwind_get_return_address(struct unwind_state *state)
> +static unsigned long get_return_address(struct unwind_state *state)
> {
> - if (unwind_done(state))
> - return 0;
> return state->pc;
> }
> -EXPORT_SYMBOL_GPL(unwind_get_return_address);
>
> -void unwind_start(struct unwind_state *state, struct task_struct *task,
> +static void start(struct unwind_state *state, struct task_struct *task,
> struct pt_regs *regs)
> {
> - memset(state, 0, sizeof(*state));
> -
> - if (regs) {
> - state->sp = regs->regs[3];
> - state->pc = regs->csr_era;
> - } else if (task == current || task == NULL) {
> - state->sp = (unsigned long)__builtin_frame_address(0);
> - state->pc = (unsigned long)__builtin_return_address(0);
> - } else {
> - state->sp = thread_saved_fp(task);
> - state->pc = thread_saved_ra(task);
> - }
> -
> - state->task = task;
> - state->first = true;
> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
> - get_stack_info(state->sp, state->task, &state->stack_info);
> -
> if (!unwind_done(state) && !__kernel_text_address(state->pc))
> unwind_next_frame(state);
> }
> -EXPORT_SYMBOL_GPL(unwind_start);
>
> -bool unwind_next_frame(struct unwind_state *state)
> +static bool next_frame(struct unwind_state *state)
> {
> struct stack_info *info = &state->stack_info;
> unsigned long addr;
>
> - if (unwind_done(state))
> - return false;
> -
> - if (state->first)
> - state->first = false;
> -
> do {
> for (state->sp += sizeof(unsigned long);
> state->sp < info->end;
> @@ -68,4 +40,9 @@ bool unwind_next_frame(struct unwind_state *state)
>
> return false;
> }
> -EXPORT_SYMBOL_GPL(unwind_next_frame);
> +
> +const struct unwinder_ops unwinder_guess = {
> + .unwind_start = start,
> + .unwind_next_frame = next_frame,
> + .unwind_get_return_address = get_return_address,
> +};
> diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
> index f7994ed05f04..beb57ea24da2 100644
> --- a/arch/loongarch/kernel/unwind_prologue.c
> +++ b/arch/loongarch/kernel/unwind_prologue.c
> @@ -19,31 +19,19 @@ static inline void unwind_state_fixup(struct unwind_state *state)
> #endif
> }
>
> -unsigned long unwind_get_return_address(struct unwind_state *state)
> +static unsigned long get_return_address(struct unwind_state *state)
> {
> - if (unwind_done(state))
> - return 0;
> return state->pc;
> }
> -EXPORT_SYMBOL_GPL(unwind_get_return_address);
> -
> -static bool unwind_by_guess(struct unwind_state *state)
> -{
> - struct stack_info *info = &state->stack_info;
> - unsigned long addr;
> -
> - for (state->sp += sizeof(unsigned long);
> - state->sp < info->end;
> - state->sp += sizeof(unsigned long)) {
> - addr = *(unsigned long *)(state->sp);
> - state->pc = unwind_graph_addr(state, addr, state->sp + 8);
> - if (__kernel_text_address(state->pc))
> - return true;
> - }
> -
> - return false;
> -}
>
> +/*
> + * LoongArch function prologue like follows,
> + * [others instructions not use stack var]
> + * addi.d sp, sp, -imm
> + * st.d xx, sp, offset <- save callee saved regs and
> + * st.d yy, sp, offset save ra if function is nest.
> + * [others instructions]
> + */
> static bool unwind_by_prologue(struct unwind_state *state)
> {
> long frame_ra = -1;
> @@ -89,6 +77,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
> ip++;
> }
>
> + /*
> + * Not find stack alloc action, PC may be in a leaf function. Only the
> + * first being true is reasonable, otherwise indicate analysis is broken.
> + */
> if (!frame_size) {
> if (state->first)
> goto first;
> @@ -106,6 +98,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
> ip++;
> }
>
> + /* Not find save $ra action, PC may be in a leaf function, too. */
> if (frame_ra < 0) {
> if (state->first) {
> state->sp = state->sp + frame_size;
> @@ -114,96 +107,63 @@ static bool unwind_by_prologue(struct unwind_state *state)
> return false;
> }
>
> - if (state->first)
> - state->first = false;
> -
> state->pc = *(unsigned long *)(state->sp + frame_ra);
> state->sp = state->sp + frame_size;
> goto out;
>
> first:
> - state->first = false;
> - if (state->pc == state->ra)
> - return false;
> -
> state->pc = state->ra;
>
> out:
> + state->first = false;
> unwind_state_fixup(state);
> return !!__kernel_text_address(state->pc);
> }
>
> -void unwind_start(struct unwind_state *state, struct task_struct *task,
> +static void start(struct unwind_state *state, struct task_struct *task,
> struct pt_regs *regs)
> {
> - memset(state, 0, sizeof(*state));
> - state->type = UNWINDER_PROLOGUE;
> -
> - if (regs) {
> - state->sp = regs->regs[3];
> - state->pc = regs->csr_era;
> - state->ra = regs->regs[1];
> - if (!__kernel_text_address(state->pc))
> - state->type = UNWINDER_GUESS;
> - } else if (task == current || task == NULL) {
> - state->sp = (unsigned long)__builtin_frame_address(0);
> - state->pc = (unsigned long)__builtin_return_address(0);
> - state->ra = 0;
> - } else {
> - state->sp = thread_saved_fp(task);
> - state->pc = thread_saved_ra(task);
> - state->ra = 0;
> - }
> -
> - state->task = task;
> state->first = true;
> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
> - get_stack_info(state->sp, state->task, &state->stack_info);
>
> - if (!unwind_done(state) && !__kernel_text_address(state->pc))
> - unwind_next_frame(state);
> + /*
> + * The current PC is not kernel text address, we cannot find its
> + * relative symbol. Thus, prologue analysis will be broken. Luckly,
> + * we can use the guess unwinder.
> + */
> + if (!__kernel_text_address(state->pc)) {
> + unwind_register_unwinder(state, &unwinder_guess);
> + if (!unwind_done(state))
> + unwind_next_frame(state);
> + }
> }
> -EXPORT_SYMBOL_GPL(unwind_start);
>
> -bool unwind_next_frame(struct unwind_state *state)
> +static bool next_frame(struct unwind_state *state)
> {
> struct stack_info *info = &state->stack_info;
> struct pt_regs *regs;
> unsigned long pc;
>
> - if (unwind_done(state))
> - return false;
> -
> do {
> - switch (state->type) {
> - case UNWINDER_GUESS:
> - state->first = false;
> - if (unwind_by_guess(state))
> - return true;
> - break;
> -
> - case UNWINDER_PROLOGUE:
> - if (unwind_by_prologue(state)) {
> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
> - return true;
> - }
> + if (unwind_by_prologue(state)) {
> + state->pc = unwind_graph_addr(state, state->pc, state->sp);
> + return true;
> + }
>
> - if (info->type == STACK_TYPE_IRQ &&
> - info->end == state->sp) {
> - regs = (struct pt_regs *)info->next_sp;
> - pc = regs->csr_era;
> + if (info->type == STACK_TYPE_IRQ &&
> + info->end == state->sp) {
> + regs = (struct pt_regs *)info->next_sp;
> + pc = regs->csr_era;
>
> - if (user_mode(regs) || !__kernel_text_address(pc))
> - return false;
> + if (user_mode(regs) || !__kernel_text_address(pc))
> + return false;
>
> - state->first = true;
> - state->ra = regs->regs[1];
> - state->sp = regs->regs[3];
> - state->pc = pc;
> - get_stack_info(state->sp, state->task, info);
> + state->first = true;
> + state->ra = regs->regs[1];
> + state->sp = regs->regs[3];
> + state->pc = pc;
> + get_stack_info(state->sp, state->task, info);
>
> - return true;
> - }
> + return true;
> }
>
> state->sp = info->next_sp;
> @@ -212,4 +172,9 @@ bool unwind_next_frame(struct unwind_state *state)
>
> return false;
> }
> -EXPORT_SYMBOL_GPL(unwind_next_frame);
> +
> +const struct unwinder_ops unwinder_prologue = {
> + .unwind_start = start,
> + .unwind_next_frame = next_frame,
> + .unwind_get_return_address = get_return_address,
> +};
> --
> 2.34.3
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH v2 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder
2023-01-01 9:56 ` Huacai Chen
@ 2023-01-03 8:40 ` Jinyang He
2023-01-03 8:58 ` Huacai Chen
0 siblings, 1 reply; 9+ messages in thread
From: Jinyang He @ 2023-01-03 8:40 UTC (permalink / raw)
To: Huacai Chen
Cc: WANG Xuerui, Qing Zhang, loongarch, linux-kernel, Steven Rostedt,
Masami Hiramatsu, Mark Rutland
On 2023-01-01 17:56, Huacai Chen wrote:
> Hi, Jinyang,
>
> On Thu, Dec 29, 2022 at 2:15 PM Jinyang He <hejinyang@loongson.cn> wrote:
>> The prolugue unwinder rely on symbol info. When PC is not in kernel
>> text address, it cannot find relative symbol info and it will be broken.
>> The guess unwinder will be used in this case. And the guess unwinder
>> codes in prolugue unwinder is redundant. Strip it out and set the
>> unwinder info in unwind_state.
>>
>> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
>> ---
>> arch/loongarch/include/asm/unwind.h | 26 ++++-
>> arch/loongarch/kernel/Makefile | 3 +-
>> arch/loongarch/kernel/traps.c | 3 -
>> arch/loongarch/kernel/unwind.c | 52 +++++++++
>> arch/loongarch/kernel/unwind_guess.c | 41 ++------
>> arch/loongarch/kernel/unwind_prologue.c | 133 +++++++++---------------
>> 6 files changed, 132 insertions(+), 126 deletions(-)
>> create mode 100644 arch/loongarch/kernel/unwind.c
>>
>> diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
>> index 6ece48f0ff77..4a55fd7b77ad 100644
>> --- a/arch/loongarch/include/asm/unwind.h
>> +++ b/arch/loongarch/include/asm/unwind.h
>> @@ -13,20 +13,30 @@
>> #include <asm/ptrace.h>
>> #include <asm/stacktrace.h>
>>
>> -enum unwinder_type {
>> - UNWINDER_GUESS,
>> - UNWINDER_PROLOGUE,
>> -};
>> +struct unwinder_ops;
>>
>> struct unwind_state {
>> - char type; /* UNWINDER_XXX */
>> struct stack_info stack_info;
>> struct task_struct *task;
>> bool first, error, is_ftrace;
>> int graph_idx;
>> unsigned long sp, pc, ra;
>> + const struct unwinder_ops *ops;
>> +};
>> +
>> +struct unwinder_ops {
>> + void (*unwind_start)(struct unwind_state *state,
>> + struct task_struct *task, struct pt_regs *regs);
>> + bool (*unwind_next_frame)(struct unwind_state *state);
>> + unsigned long (*unwind_get_return_address)(struct unwind_state *state);
>> };
>>
>> +extern const struct unwinder_ops *default_unwinder;
>> +extern const struct unwinder_ops unwinder_guess;
>> +#ifdef CONFIG_UNWINDER_PROLOGUE
>> +extern const struct unwinder_ops unwinder_prologue;
>> +#endif
>> +
>> void unwind_start(struct unwind_state *state,
>> struct task_struct *task, struct pt_regs *regs);
>> bool unwind_next_frame(struct unwind_state *state);
>> @@ -49,4 +59,10 @@ static inline unsigned long unwind_graph_addr(struct unwind_state *state,
>> return ftrace_graph_ret_addr(state->task, &state->graph_idx,
>> pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
>> }
>> +
>> +static inline void unwind_register_unwinder(struct unwind_state *state,
>> + const struct unwinder_ops *unwinder)
>> +{
>> + state->ops = unwinder;
>> +}
>> #endif /* _ASM_UNWIND_H */
>> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
>> index 7ca65195f7f8..cb6029ea3ea9 100644
>> --- a/arch/loongarch/kernel/Makefile
>> +++ b/arch/loongarch/kernel/Makefile
>> @@ -8,7 +8,7 @@ extra-y := vmlinux.lds
>> obj-y += head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
>> traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
>> elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \
>> - alternative.o unaligned.o
>> + alternative.o unaligned.o unwind.o unwind_guess.o
>>
>> obj-$(CONFIG_ACPI) += acpi.o
>> obj-$(CONFIG_EFI) += efi.o
>> @@ -42,7 +42,6 @@ obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o
>> obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
>> obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
>>
>> -obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
>> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
> We do have CONFIG_UNWINDER_GUESS and I don't like to build guess
> unwinder unconditionally, maybe we can refactor it to make the
> unwinder still user selectable.
In order to provide backtrace info to the user, prologue unwinder
will use guess unwinder when its first pc is not a kernel address,
such as the first PC is in ebpf generated codes. This patch is intended
to extract guess unwinder codes to avoid redundant codes. And if we provide
a new unwinder in the future like orc unwinder which take effect after
orc_init is set, we can use another backup unwinder like guess unwinder in
case we need backtrace before orc_init being set.
If you mind this, could we just do as follows,
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o unwind_guess.o
Or copy the guess unwinder codes to unwind_prologue.c and set another
name for guess unwinder.
Thanks,
Jinyang
> Huacai
>> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
>> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
>> index 3adc44832205..1ea14f6c18d3 100644
>> --- a/arch/loongarch/kernel/traps.c
>> +++ b/arch/loongarch/kernel/traps.c
>> @@ -72,9 +72,6 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
>> if (!task)
>> task = current;
>>
>> - if (user_mode(regs))
>> - state.type = UNWINDER_GUESS;
>> -
>> printk("%sCall Trace:", loglvl);
>> for (unwind_start(&state, task, pregs);
>> !unwind_done(&state); unwind_next_frame(&state)) {
>> diff --git a/arch/loongarch/kernel/unwind.c b/arch/loongarch/kernel/unwind.c
>> new file mode 100644
>> index 000000000000..24d2cf99bfb6
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/unwind.c
>> @@ -0,0 +1,52 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#include <asm/unwind.h>
>> +
>> +#if defined(CONFIG_UNWINDER_GUESS)
>> +const struct unwinder_ops *default_unwinder = &unwinder_guess;
>> +#elif defined(CONFIG_UNWINDER_PROLOGUE)
>> +const struct unwinder_ops *default_unwinder = &unwinder_prologue;
>> +#endif
>> +
>> +unsigned long unwind_get_return_address(struct unwind_state *state)
>> +{
>> + if (!state->ops || unwind_done(state))
>> + return 0;
>> + return state->ops->unwind_get_return_address(state);
>> +}
>> +EXPORT_SYMBOL_GPL(unwind_get_return_address);
>> +
>> +void unwind_start(struct unwind_state *state, struct task_struct *task,
>> + struct pt_regs *regs)
>> +{
>> + memset(state, 0, sizeof(*state));
>> + unwind_register_unwinder(state, default_unwinder);
>> + if (regs) {
>> + state->sp = regs->regs[3];
>> + state->pc = regs->csr_era;
>> + state->ra = regs->regs[1];
>> + } else if (task == current || task == NULL) {
>> + state->sp = (unsigned long)__builtin_frame_address(0);
>> + state->pc = (unsigned long)__builtin_return_address(0);
>> + state->ra = 0;
>> + } else {
>> + state->sp = thread_saved_fp(task);
>> + state->pc = thread_saved_ra(task);
>> + state->ra = 0;
>> + }
>> + state->task = task;
>> + get_stack_info(state->sp, state->task, &state->stack_info);
>> + state->pc = unwind_graph_addr(state, state->pc, state->sp);
>> + state->ops->unwind_start(state, task, regs);
>> +}
>> +EXPORT_SYMBOL_GPL(unwind_start);
>> +
>> +bool unwind_next_frame(struct unwind_state *state)
>> +{
>> + if (!state->ops || unwind_done(state))
>> + return false;
>> + return state->ops->unwind_next_frame(state);
>> +}
>> +EXPORT_SYMBOL_GPL(unwind_next_frame);
>> diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
>> index 935d24f8c95c..b7ca2b88ac63 100644
>> --- a/arch/loongarch/kernel/unwind_guess.c
>> +++ b/arch/loongarch/kernel/unwind_guess.c
>> @@ -7,51 +7,23 @@
>>
>> #include <asm/unwind.h>
>>
>> -unsigned long unwind_get_return_address(struct unwind_state *state)
>> +static unsigned long get_return_address(struct unwind_state *state)
>> {
>> - if (unwind_done(state))
>> - return 0;
>> return state->pc;
>> }
>> -EXPORT_SYMBOL_GPL(unwind_get_return_address);
>>
>> -void unwind_start(struct unwind_state *state, struct task_struct *task,
>> +static void start(struct unwind_state *state, struct task_struct *task,
>> struct pt_regs *regs)
>> {
>> - memset(state, 0, sizeof(*state));
>> -
>> - if (regs) {
>> - state->sp = regs->regs[3];
>> - state->pc = regs->csr_era;
>> - } else if (task == current || task == NULL) {
>> - state->sp = (unsigned long)__builtin_frame_address(0);
>> - state->pc = (unsigned long)__builtin_return_address(0);
>> - } else {
>> - state->sp = thread_saved_fp(task);
>> - state->pc = thread_saved_ra(task);
>> - }
>> -
>> - state->task = task;
>> - state->first = true;
>> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
>> - get_stack_info(state->sp, state->task, &state->stack_info);
>> -
>> if (!unwind_done(state) && !__kernel_text_address(state->pc))
>> unwind_next_frame(state);
>> }
>> -EXPORT_SYMBOL_GPL(unwind_start);
>>
>> -bool unwind_next_frame(struct unwind_state *state)
>> +static bool next_frame(struct unwind_state *state)
>> {
>> struct stack_info *info = &state->stack_info;
>> unsigned long addr;
>>
>> - if (unwind_done(state))
>> - return false;
>> -
>> - if (state->first)
>> - state->first = false;
>> -
>> do {
>> for (state->sp += sizeof(unsigned long);
>> state->sp < info->end;
>> @@ -68,4 +40,9 @@ bool unwind_next_frame(struct unwind_state *state)
>>
>> return false;
>> }
>> -EXPORT_SYMBOL_GPL(unwind_next_frame);
>> +
>> +const struct unwinder_ops unwinder_guess = {
>> + .unwind_start = start,
>> + .unwind_next_frame = next_frame,
>> + .unwind_get_return_address = get_return_address,
>> +};
>> diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
>> index f7994ed05f04..beb57ea24da2 100644
>> --- a/arch/loongarch/kernel/unwind_prologue.c
>> +++ b/arch/loongarch/kernel/unwind_prologue.c
>> @@ -19,31 +19,19 @@ static inline void unwind_state_fixup(struct unwind_state *state)
>> #endif
>> }
>>
>> -unsigned long unwind_get_return_address(struct unwind_state *state)
>> +static unsigned long get_return_address(struct unwind_state *state)
>> {
>> - if (unwind_done(state))
>> - return 0;
>> return state->pc;
>> }
>> -EXPORT_SYMBOL_GPL(unwind_get_return_address);
>> -
>> -static bool unwind_by_guess(struct unwind_state *state)
>> -{
>> - struct stack_info *info = &state->stack_info;
>> - unsigned long addr;
>> -
>> - for (state->sp += sizeof(unsigned long);
>> - state->sp < info->end;
>> - state->sp += sizeof(unsigned long)) {
>> - addr = *(unsigned long *)(state->sp);
>> - state->pc = unwind_graph_addr(state, addr, state->sp + 8);
>> - if (__kernel_text_address(state->pc))
>> - return true;
>> - }
>> -
>> - return false;
>> -}
>>
>> +/*
>> + * LoongArch function prologue like follows,
>> + * [others instructions not use stack var]
>> + * addi.d sp, sp, -imm
>> + * st.d xx, sp, offset <- save callee saved regs and
>> + * st.d yy, sp, offset save ra if function is nest.
>> + * [others instructions]
>> + */
>> static bool unwind_by_prologue(struct unwind_state *state)
>> {
>> long frame_ra = -1;
>> @@ -89,6 +77,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
>> ip++;
>> }
>>
>> + /*
>> + * Not find stack alloc action, PC may be in a leaf function. Only the
>> + * first being true is reasonable, otherwise indicate analysis is broken.
>> + */
>> if (!frame_size) {
>> if (state->first)
>> goto first;
>> @@ -106,6 +98,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
>> ip++;
>> }
>>
>> + /* Not find save $ra action, PC may be in a leaf function, too. */
>> if (frame_ra < 0) {
>> if (state->first) {
>> state->sp = state->sp + frame_size;
>> @@ -114,96 +107,63 @@ static bool unwind_by_prologue(struct unwind_state *state)
>> return false;
>> }
>>
>> - if (state->first)
>> - state->first = false;
>> -
>> state->pc = *(unsigned long *)(state->sp + frame_ra);
>> state->sp = state->sp + frame_size;
>> goto out;
>>
>> first:
>> - state->first = false;
>> - if (state->pc == state->ra)
>> - return false;
>> -
>> state->pc = state->ra;
>>
>> out:
>> + state->first = false;
>> unwind_state_fixup(state);
>> return !!__kernel_text_address(state->pc);
>> }
>>
>> -void unwind_start(struct unwind_state *state, struct task_struct *task,
>> +static void start(struct unwind_state *state, struct task_struct *task,
>> struct pt_regs *regs)
>> {
>> - memset(state, 0, sizeof(*state));
>> - state->type = UNWINDER_PROLOGUE;
>> -
>> - if (regs) {
>> - state->sp = regs->regs[3];
>> - state->pc = regs->csr_era;
>> - state->ra = regs->regs[1];
>> - if (!__kernel_text_address(state->pc))
>> - state->type = UNWINDER_GUESS;
>> - } else if (task == current || task == NULL) {
>> - state->sp = (unsigned long)__builtin_frame_address(0);
>> - state->pc = (unsigned long)__builtin_return_address(0);
>> - state->ra = 0;
>> - } else {
>> - state->sp = thread_saved_fp(task);
>> - state->pc = thread_saved_ra(task);
>> - state->ra = 0;
>> - }
>> -
>> - state->task = task;
>> state->first = true;
>> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
>> - get_stack_info(state->sp, state->task, &state->stack_info);
>>
>> - if (!unwind_done(state) && !__kernel_text_address(state->pc))
>> - unwind_next_frame(state);
>> + /*
>> + * The current PC is not kernel text address, we cannot find its
>> + * relative symbol. Thus, prologue analysis will be broken. Luckly,
>> + * we can use the guess unwinder.
>> + */
>> + if (!__kernel_text_address(state->pc)) {
>> + unwind_register_unwinder(state, &unwinder_guess);
>> + if (!unwind_done(state))
>> + unwind_next_frame(state);
>> + }
>> }
>> -EXPORT_SYMBOL_GPL(unwind_start);
>>
>> -bool unwind_next_frame(struct unwind_state *state)
>> +static bool next_frame(struct unwind_state *state)
>> {
>> struct stack_info *info = &state->stack_info;
>> struct pt_regs *regs;
>> unsigned long pc;
>>
>> - if (unwind_done(state))
>> - return false;
>> -
>> do {
>> - switch (state->type) {
>> - case UNWINDER_GUESS:
>> - state->first = false;
>> - if (unwind_by_guess(state))
>> - return true;
>> - break;
>> -
>> - case UNWINDER_PROLOGUE:
>> - if (unwind_by_prologue(state)) {
>> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
>> - return true;
>> - }
>> + if (unwind_by_prologue(state)) {
>> + state->pc = unwind_graph_addr(state, state->pc, state->sp);
>> + return true;
>> + }
>>
>> - if (info->type == STACK_TYPE_IRQ &&
>> - info->end == state->sp) {
>> - regs = (struct pt_regs *)info->next_sp;
>> - pc = regs->csr_era;
>> + if (info->type == STACK_TYPE_IRQ &&
>> + info->end == state->sp) {
>> + regs = (struct pt_regs *)info->next_sp;
>> + pc = regs->csr_era;
>>
>> - if (user_mode(regs) || !__kernel_text_address(pc))
>> - return false;
>> + if (user_mode(regs) || !__kernel_text_address(pc))
>> + return false;
>>
>> - state->first = true;
>> - state->ra = regs->regs[1];
>> - state->sp = regs->regs[3];
>> - state->pc = pc;
>> - get_stack_info(state->sp, state->task, info);
>> + state->first = true;
>> + state->ra = regs->regs[1];
>> + state->sp = regs->regs[3];
>> + state->pc = pc;
>> + get_stack_info(state->sp, state->task, info);
>>
>> - return true;
>> - }
>> + return true;
>> }
>>
>> state->sp = info->next_sp;
>> @@ -212,4 +172,9 @@ bool unwind_next_frame(struct unwind_state *state)
>>
>> return false;
>> }
>> -EXPORT_SYMBOL_GPL(unwind_next_frame);
>> +
>> +const struct unwinder_ops unwinder_prologue = {
>> + .unwind_start = start,
>> + .unwind_next_frame = next_frame,
>> + .unwind_get_return_address = get_return_address,
>> +};
>> --
>> 2.34.3
>>
>>
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH v2 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder
2023-01-03 8:40 ` Jinyang He
@ 2023-01-03 8:58 ` Huacai Chen
0 siblings, 0 replies; 9+ messages in thread
From: Huacai Chen @ 2023-01-03 8:58 UTC (permalink / raw)
To: Jinyang He
Cc: WANG Xuerui, Qing Zhang, loongarch, linux-kernel, Steven Rostedt,
Masami Hiramatsu, Mark Rutland
On Tue, Jan 3, 2023 at 4:41 PM Jinyang He <hejinyang@loongson.cn> wrote:
>
> On 2023-01-01 17:56, Huacai Chen wrote:
>
> > Hi, Jinyang,
> >
> > On Thu, Dec 29, 2022 at 2:15 PM Jinyang He <hejinyang@loongson.cn> wrote:
> >> The prolugue unwinder rely on symbol info. When PC is not in kernel
> >> text address, it cannot find relative symbol info and it will be broken.
> >> The guess unwinder will be used in this case. And the guess unwinder
> >> codes in prolugue unwinder is redundant. Strip it out and set the
> >> unwinder info in unwind_state.
> >>
> >> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
> >> ---
> >> arch/loongarch/include/asm/unwind.h | 26 ++++-
> >> arch/loongarch/kernel/Makefile | 3 +-
> >> arch/loongarch/kernel/traps.c | 3 -
> >> arch/loongarch/kernel/unwind.c | 52 +++++++++
> >> arch/loongarch/kernel/unwind_guess.c | 41 ++------
> >> arch/loongarch/kernel/unwind_prologue.c | 133 +++++++++---------------
> >> 6 files changed, 132 insertions(+), 126 deletions(-)
> >> create mode 100644 arch/loongarch/kernel/unwind.c
> >>
> >> diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
> >> index 6ece48f0ff77..4a55fd7b77ad 100644
> >> --- a/arch/loongarch/include/asm/unwind.h
> >> +++ b/arch/loongarch/include/asm/unwind.h
> >> @@ -13,20 +13,30 @@
> >> #include <asm/ptrace.h>
> >> #include <asm/stacktrace.h>
> >>
> >> -enum unwinder_type {
> >> - UNWINDER_GUESS,
> >> - UNWINDER_PROLOGUE,
> >> -};
> >> +struct unwinder_ops;
> >>
> >> struct unwind_state {
> >> - char type; /* UNWINDER_XXX */
> >> struct stack_info stack_info;
> >> struct task_struct *task;
> >> bool first, error, is_ftrace;
> >> int graph_idx;
> >> unsigned long sp, pc, ra;
> >> + const struct unwinder_ops *ops;
> >> +};
> >> +
> >> +struct unwinder_ops {
> >> + void (*unwind_start)(struct unwind_state *state,
> >> + struct task_struct *task, struct pt_regs *regs);
> >> + bool (*unwind_next_frame)(struct unwind_state *state);
> >> + unsigned long (*unwind_get_return_address)(struct unwind_state *state);
> >> };
> >>
> >> +extern const struct unwinder_ops *default_unwinder;
> >> +extern const struct unwinder_ops unwinder_guess;
> >> +#ifdef CONFIG_UNWINDER_PROLOGUE
> >> +extern const struct unwinder_ops unwinder_prologue;
> >> +#endif
> >> +
> >> void unwind_start(struct unwind_state *state,
> >> struct task_struct *task, struct pt_regs *regs);
> >> bool unwind_next_frame(struct unwind_state *state);
> >> @@ -49,4 +59,10 @@ static inline unsigned long unwind_graph_addr(struct unwind_state *state,
> >> return ftrace_graph_ret_addr(state->task, &state->graph_idx,
> >> pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
> >> }
> >> +
> >> +static inline void unwind_register_unwinder(struct unwind_state *state,
> >> + const struct unwinder_ops *unwinder)
> >> +{
> >> + state->ops = unwinder;
> >> +}
> >> #endif /* _ASM_UNWIND_H */
> >> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> >> index 7ca65195f7f8..cb6029ea3ea9 100644
> >> --- a/arch/loongarch/kernel/Makefile
> >> +++ b/arch/loongarch/kernel/Makefile
> >> @@ -8,7 +8,7 @@ extra-y := vmlinux.lds
> >> obj-y += head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
> >> traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
> >> elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \
> >> - alternative.o unaligned.o
> >> + alternative.o unaligned.o unwind.o unwind_guess.o
> >>
> >> obj-$(CONFIG_ACPI) += acpi.o
> >> obj-$(CONFIG_EFI) += efi.o
> >> @@ -42,7 +42,6 @@ obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o
> >> obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
> >> obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
> >>
> >> -obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
> >> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
> > We do have CONFIG_UNWINDER_GUESS and I don't like to build guess
> > unwinder unconditionally, maybe we can refactor it to make the
> > unwinder still user selectable.
>
>
> In order to provide backtrace info to the user, prologue unwinder
> will use guess unwinder when its first pc is not a kernel address,
> such as the first PC is in ebpf generated codes. This patch is intended
> to extract guess unwinder codes to avoid redundant codes. And if we provide
> a new unwinder in the future like orc unwinder which take effect after
> orc_init is set, we can use another backup unwinder like guess unwinder in
> case we need backtrace before orc_init being set.
>
> If you mind this, could we just do as follows,
>
> obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o unwind_guess.o
>
> Or copy the guess unwinder codes to unwind_prologue.c and set another
> name for guess unwinder.
Can we move common functions to unwind.c (or something similar) and
make unwind_guess.c/unwind_prologue.c as a frontend?
Huacai
>
>
> Thanks,
>
> Jinyang
>
> > Huacai
> >> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
> >> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> >> index 3adc44832205..1ea14f6c18d3 100644
> >> --- a/arch/loongarch/kernel/traps.c
> >> +++ b/arch/loongarch/kernel/traps.c
> >> @@ -72,9 +72,6 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
> >> if (!task)
> >> task = current;
> >>
> >> - if (user_mode(regs))
> >> - state.type = UNWINDER_GUESS;
> >> -
> >> printk("%sCall Trace:", loglvl);
> >> for (unwind_start(&state, task, pregs);
> >> !unwind_done(&state); unwind_next_frame(&state)) {
> >> diff --git a/arch/loongarch/kernel/unwind.c b/arch/loongarch/kernel/unwind.c
> >> new file mode 100644
> >> index 000000000000..24d2cf99bfb6
> >> --- /dev/null
> >> +++ b/arch/loongarch/kernel/unwind.c
> >> @@ -0,0 +1,52 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> >> + */
> >> +#include <asm/unwind.h>
> >> +
> >> +#if defined(CONFIG_UNWINDER_GUESS)
> >> +const struct unwinder_ops *default_unwinder = &unwinder_guess;
> >> +#elif defined(CONFIG_UNWINDER_PROLOGUE)
> >> +const struct unwinder_ops *default_unwinder = &unwinder_prologue;
> >> +#endif
> >> +
> >> +unsigned long unwind_get_return_address(struct unwind_state *state)
> >> +{
> >> + if (!state->ops || unwind_done(state))
> >> + return 0;
> >> + return state->ops->unwind_get_return_address(state);
> >> +}
> >> +EXPORT_SYMBOL_GPL(unwind_get_return_address);
> >> +
> >> +void unwind_start(struct unwind_state *state, struct task_struct *task,
> >> + struct pt_regs *regs)
> >> +{
> >> + memset(state, 0, sizeof(*state));
> >> + unwind_register_unwinder(state, default_unwinder);
> >> + if (regs) {
> >> + state->sp = regs->regs[3];
> >> + state->pc = regs->csr_era;
> >> + state->ra = regs->regs[1];
> >> + } else if (task == current || task == NULL) {
> >> + state->sp = (unsigned long)__builtin_frame_address(0);
> >> + state->pc = (unsigned long)__builtin_return_address(0);
> >> + state->ra = 0;
> >> + } else {
> >> + state->sp = thread_saved_fp(task);
> >> + state->pc = thread_saved_ra(task);
> >> + state->ra = 0;
> >> + }
> >> + state->task = task;
> >> + get_stack_info(state->sp, state->task, &state->stack_info);
> >> + state->pc = unwind_graph_addr(state, state->pc, state->sp);
> >> + state->ops->unwind_start(state, task, regs);
> >> +}
> >> +EXPORT_SYMBOL_GPL(unwind_start);
> >> +
> >> +bool unwind_next_frame(struct unwind_state *state)
> >> +{
> >> + if (!state->ops || unwind_done(state))
> >> + return false;
> >> + return state->ops->unwind_next_frame(state);
> >> +}
> >> +EXPORT_SYMBOL_GPL(unwind_next_frame);
> >> diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
> >> index 935d24f8c95c..b7ca2b88ac63 100644
> >> --- a/arch/loongarch/kernel/unwind_guess.c
> >> +++ b/arch/loongarch/kernel/unwind_guess.c
> >> @@ -7,51 +7,23 @@
> >>
> >> #include <asm/unwind.h>
> >>
> >> -unsigned long unwind_get_return_address(struct unwind_state *state)
> >> +static unsigned long get_return_address(struct unwind_state *state)
> >> {
> >> - if (unwind_done(state))
> >> - return 0;
> >> return state->pc;
> >> }
> >> -EXPORT_SYMBOL_GPL(unwind_get_return_address);
> >>
> >> -void unwind_start(struct unwind_state *state, struct task_struct *task,
> >> +static void start(struct unwind_state *state, struct task_struct *task,
> >> struct pt_regs *regs)
> >> {
> >> - memset(state, 0, sizeof(*state));
> >> -
> >> - if (regs) {
> >> - state->sp = regs->regs[3];
> >> - state->pc = regs->csr_era;
> >> - } else if (task == current || task == NULL) {
> >> - state->sp = (unsigned long)__builtin_frame_address(0);
> >> - state->pc = (unsigned long)__builtin_return_address(0);
> >> - } else {
> >> - state->sp = thread_saved_fp(task);
> >> - state->pc = thread_saved_ra(task);
> >> - }
> >> -
> >> - state->task = task;
> >> - state->first = true;
> >> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
> >> - get_stack_info(state->sp, state->task, &state->stack_info);
> >> -
> >> if (!unwind_done(state) && !__kernel_text_address(state->pc))
> >> unwind_next_frame(state);
> >> }
> >> -EXPORT_SYMBOL_GPL(unwind_start);
> >>
> >> -bool unwind_next_frame(struct unwind_state *state)
> >> +static bool next_frame(struct unwind_state *state)
> >> {
> >> struct stack_info *info = &state->stack_info;
> >> unsigned long addr;
> >>
> >> - if (unwind_done(state))
> >> - return false;
> >> -
> >> - if (state->first)
> >> - state->first = false;
> >> -
> >> do {
> >> for (state->sp += sizeof(unsigned long);
> >> state->sp < info->end;
> >> @@ -68,4 +40,9 @@ bool unwind_next_frame(struct unwind_state *state)
> >>
> >> return false;
> >> }
> >> -EXPORT_SYMBOL_GPL(unwind_next_frame);
> >> +
> >> +const struct unwinder_ops unwinder_guess = {
> >> + .unwind_start = start,
> >> + .unwind_next_frame = next_frame,
> >> + .unwind_get_return_address = get_return_address,
> >> +};
> >> diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
> >> index f7994ed05f04..beb57ea24da2 100644
> >> --- a/arch/loongarch/kernel/unwind_prologue.c
> >> +++ b/arch/loongarch/kernel/unwind_prologue.c
> >> @@ -19,31 +19,19 @@ static inline void unwind_state_fixup(struct unwind_state *state)
> >> #endif
> >> }
> >>
> >> -unsigned long unwind_get_return_address(struct unwind_state *state)
> >> +static unsigned long get_return_address(struct unwind_state *state)
> >> {
> >> - if (unwind_done(state))
> >> - return 0;
> >> return state->pc;
> >> }
> >> -EXPORT_SYMBOL_GPL(unwind_get_return_address);
> >> -
> >> -static bool unwind_by_guess(struct unwind_state *state)
> >> -{
> >> - struct stack_info *info = &state->stack_info;
> >> - unsigned long addr;
> >> -
> >> - for (state->sp += sizeof(unsigned long);
> >> - state->sp < info->end;
> >> - state->sp += sizeof(unsigned long)) {
> >> - addr = *(unsigned long *)(state->sp);
> >> - state->pc = unwind_graph_addr(state, addr, state->sp + 8);
> >> - if (__kernel_text_address(state->pc))
> >> - return true;
> >> - }
> >> -
> >> - return false;
> >> -}
> >>
> >> +/*
> >> + * LoongArch function prologue like follows,
> >> + * [others instructions not use stack var]
> >> + * addi.d sp, sp, -imm
> >> + * st.d xx, sp, offset <- save callee saved regs and
> >> + * st.d yy, sp, offset save ra if function is nest.
> >> + * [others instructions]
> >> + */
> >> static bool unwind_by_prologue(struct unwind_state *state)
> >> {
> >> long frame_ra = -1;
> >> @@ -89,6 +77,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
> >> ip++;
> >> }
> >>
> >> + /*
> >> + * Not find stack alloc action, PC may be in a leaf function. Only the
> >> + * first being true is reasonable, otherwise indicate analysis is broken.
> >> + */
> >> if (!frame_size) {
> >> if (state->first)
> >> goto first;
> >> @@ -106,6 +98,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
> >> ip++;
> >> }
> >>
> >> + /* Not find save $ra action, PC may be in a leaf function, too. */
> >> if (frame_ra < 0) {
> >> if (state->first) {
> >> state->sp = state->sp + frame_size;
> >> @@ -114,96 +107,63 @@ static bool unwind_by_prologue(struct unwind_state *state)
> >> return false;
> >> }
> >>
> >> - if (state->first)
> >> - state->first = false;
> >> -
> >> state->pc = *(unsigned long *)(state->sp + frame_ra);
> >> state->sp = state->sp + frame_size;
> >> goto out;
> >>
> >> first:
> >> - state->first = false;
> >> - if (state->pc == state->ra)
> >> - return false;
> >> -
> >> state->pc = state->ra;
> >>
> >> out:
> >> + state->first = false;
> >> unwind_state_fixup(state);
> >> return !!__kernel_text_address(state->pc);
> >> }
> >>
> >> -void unwind_start(struct unwind_state *state, struct task_struct *task,
> >> +static void start(struct unwind_state *state, struct task_struct *task,
> >> struct pt_regs *regs)
> >> {
> >> - memset(state, 0, sizeof(*state));
> >> - state->type = UNWINDER_PROLOGUE;
> >> -
> >> - if (regs) {
> >> - state->sp = regs->regs[3];
> >> - state->pc = regs->csr_era;
> >> - state->ra = regs->regs[1];
> >> - if (!__kernel_text_address(state->pc))
> >> - state->type = UNWINDER_GUESS;
> >> - } else if (task == current || task == NULL) {
> >> - state->sp = (unsigned long)__builtin_frame_address(0);
> >> - state->pc = (unsigned long)__builtin_return_address(0);
> >> - state->ra = 0;
> >> - } else {
> >> - state->sp = thread_saved_fp(task);
> >> - state->pc = thread_saved_ra(task);
> >> - state->ra = 0;
> >> - }
> >> -
> >> - state->task = task;
> >> state->first = true;
> >> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
> >> - get_stack_info(state->sp, state->task, &state->stack_info);
> >>
> >> - if (!unwind_done(state) && !__kernel_text_address(state->pc))
> >> - unwind_next_frame(state);
> >> + /*
> >> + * The current PC is not kernel text address, we cannot find its
> >> + * relative symbol. Thus, prologue analysis will be broken. Luckly,
> >> + * we can use the guess unwinder.
> >> + */
> >> + if (!__kernel_text_address(state->pc)) {
> >> + unwind_register_unwinder(state, &unwinder_guess);
> >> + if (!unwind_done(state))
> >> + unwind_next_frame(state);
> >> + }
> >> }
> >> -EXPORT_SYMBOL_GPL(unwind_start);
> >>
> >> -bool unwind_next_frame(struct unwind_state *state)
> >> +static bool next_frame(struct unwind_state *state)
> >> {
> >> struct stack_info *info = &state->stack_info;
> >> struct pt_regs *regs;
> >> unsigned long pc;
> >>
> >> - if (unwind_done(state))
> >> - return false;
> >> -
> >> do {
> >> - switch (state->type) {
> >> - case UNWINDER_GUESS:
> >> - state->first = false;
> >> - if (unwind_by_guess(state))
> >> - return true;
> >> - break;
> >> -
> >> - case UNWINDER_PROLOGUE:
> >> - if (unwind_by_prologue(state)) {
> >> - state->pc = unwind_graph_addr(state, state->pc, state->sp);
> >> - return true;
> >> - }
> >> + if (unwind_by_prologue(state)) {
> >> + state->pc = unwind_graph_addr(state, state->pc, state->sp);
> >> + return true;
> >> + }
> >>
> >> - if (info->type == STACK_TYPE_IRQ &&
> >> - info->end == state->sp) {
> >> - regs = (struct pt_regs *)info->next_sp;
> >> - pc = regs->csr_era;
> >> + if (info->type == STACK_TYPE_IRQ &&
> >> + info->end == state->sp) {
> >> + regs = (struct pt_regs *)info->next_sp;
> >> + pc = regs->csr_era;
> >>
> >> - if (user_mode(regs) || !__kernel_text_address(pc))
> >> - return false;
> >> + if (user_mode(regs) || !__kernel_text_address(pc))
> >> + return false;
> >>
> >> - state->first = true;
> >> - state->ra = regs->regs[1];
> >> - state->sp = regs->regs[3];
> >> - state->pc = pc;
> >> - get_stack_info(state->sp, state->task, info);
> >> + state->first = true;
> >> + state->ra = regs->regs[1];
> >> + state->sp = regs->regs[3];
> >> + state->pc = pc;
> >> + get_stack_info(state->sp, state->task, info);
> >>
> >> - return true;
> >> - }
> >> + return true;
> >> }
> >>
> >> state->sp = info->next_sp;
> >> @@ -212,4 +172,9 @@ bool unwind_next_frame(struct unwind_state *state)
> >>
> >> return false;
> >> }
> >> -EXPORT_SYMBOL_GPL(unwind_next_frame);
> >> +
> >> +const struct unwinder_ops unwinder_prologue = {
> >> + .unwind_start = start,
> >> + .unwind_next_frame = next_frame,
> >> + .unwind_get_return_address = get_return_address,
> >> +};
> >> --
> >> 2.34.3
> >>
> >>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2 5/6] LoongArch: Add generic ex-handler unwind in prologue unwinder
2022-12-29 6:15 [PATCH v2 0/5] LoongArch: Some fix and new features for unwinders Jinyang He
` (3 preceding siblings ...)
2022-12-29 6:15 ` [PATCH v2 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder Jinyang He
@ 2022-12-29 6:15 ` Jinyang He
4 siblings, 0 replies; 9+ messages in thread
From: Jinyang He @ 2022-12-29 6:15 UTC (permalink / raw)
To: Huacai Chen, WANG Xuerui, Qing Zhang
Cc: loongarch, linux-kernel, Steven Rostedt, Masami Hiramatsu, Mark Rutland
When exception is triggered, code flow go handle_\exception in some
cases. One of stackframe in this case as follows,
high -> +-------+
| REGS | <- a pt_regs
| |
| | <- ex trigger
| REGS | <- ex pt_regs <-+
| | |
| | |
low -> +-------+ ->unwind-+
When unwinder unwind to handler_\exception it cannot go on prologue
analysis. It is asynchronous code flow, we should get the next frame
PC from regs->csr_era but not from regs->regs[1]. And we copy the
handler codes to eentry in the early time and copy the handler codes
to NUMA-relative memory named pcpu_handlers if NUMA is enabled. Thus,
unwinder cannot unwind normally. Therefore, try to give some hint in
handler_\exception and fixup it in unwind_next_frame.
Reported-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/loongarch/include/asm/unwind.h | 2 +-
arch/loongarch/kernel/genex.S | 3 +
arch/loongarch/kernel/unwind_prologue.c | 100 +++++++++++++++++++++---
arch/loongarch/mm/tlb.c | 2 +-
4 files changed, 92 insertions(+), 15 deletions(-)
diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index 4a55fd7b77ad..1eb6d7f771a8 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -18,7 +18,7 @@ struct unwinder_ops;
struct unwind_state {
struct stack_info stack_info;
struct task_struct *task;
- bool first, error, is_ftrace;
+ bool first, error, reset;
int graph_idx;
unsigned long sp, pc, ra;
const struct unwinder_ops *ops;
diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.S
index 75e5be807a0d..7e5c293ed89f 100644
--- a/arch/loongarch/kernel/genex.S
+++ b/arch/loongarch/kernel/genex.S
@@ -67,14 +67,17 @@ SYM_FUNC_END(except_vec_cex)
.macro BUILD_HANDLER exception handler prep
.align 5
SYM_FUNC_START(handle_\exception)
+ 666:
BACKUP_T0T1
SAVE_ALL
build_prep_\prep
move a0, sp
la.abs t0, do_\handler
jirl ra, t0, 0
+ 668:
RESTORE_ALL_AND_RET
SYM_FUNC_END(handle_\exception)
+ SYM_DATA(unwind_hint_\exception, .word 668b - 666b)
.endm
BUILD_HANDLER ade ade badv
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index beb57ea24da2..edce9eba6b52 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -2,21 +2,100 @@
/*
* Copyright (C) 2022 Loongson Technology Corporation Limited
*/
+#include <linux/cpumask.h>
#include <linux/ftrace.h>
#include <linux/kallsyms.h>
#include <asm/inst.h>
+#include <asm/loongson.h>
#include <asm/ptrace.h>
+#include <asm/setup.h>
#include <asm/unwind.h>
-static inline void unwind_state_fixup(struct unwind_state *state)
+extern const int unwind_hint_ade;
+extern const int unwind_hint_ale;
+extern const int unwind_hint_bp;
+extern const int unwind_hint_fpe;
+extern const int unwind_hint_fpu;
+extern const int unwind_hint_lsx;
+extern const int unwind_hint_lasx;
+extern const int unwind_hint_lbt;
+extern const int unwind_hint_ri;
+extern const int unwind_hint_watch;
+extern unsigned long eentry;
+#ifdef CONFIG_NUMA
+extern unsigned long pcpu_handlers[NR_CPUS];
+#endif
+
+static inline bool scan_handler(unsigned long entry_offset)
{
-#ifdef CONFIG_DYNAMIC_FTRACE
- static unsigned long ftrace = (unsigned long)ftrace_call + 4;
+ int idx, offset;
- if (state->pc == ftrace)
- state->is_ftrace = true;
+ if (entry_offset >= EXCCODE_INT_START * VECSIZE)
+ return false;
+
+ idx = entry_offset / VECSIZE;
+ offset = entry_offset % VECSIZE;
+ switch (idx) {
+ case EXCCODE_ADE:
+ return offset == unwind_hint_ade;
+ case EXCCODE_ALE:
+ return offset == unwind_hint_ale;
+ case EXCCODE_BP:
+ return offset == unwind_hint_bp;
+ case EXCCODE_FPE:
+ return offset == unwind_hint_fpe;
+ case EXCCODE_FPDIS:
+ return offset == unwind_hint_fpu;
+ case EXCCODE_LSXDIS:
+ return offset == unwind_hint_lsx;
+ case EXCCODE_LASXDIS:
+ return offset == unwind_hint_lasx;
+ case EXCCODE_BTDIS:
+ return offset == unwind_hint_lbt;
+ case EXCCODE_INE:
+ return offset == unwind_hint_ri;
+ case EXCCODE_WATCH:
+ return offset == unwind_hint_watch;
+ default:
+ return false;
+ }
+}
+
+static inline bool fix_exceptions(unsigned long pc)
+{
+#ifdef CONFIG_NUMA
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ if (!pcpu_handlers[cpu])
+ continue;
+ if (scan_handler(pc - pcpu_handlers[cpu]))
+ return true;
+ }
#endif
+ return scan_handler(pc - eentry);
+}
+
+/*
+ * As we meet ftrace_regs_entry, reset first flag like first doing
+ * tracing. Prologue analysis will stop soon because PC is at entry.
+ */
+static inline bool fix_ftrace(unsigned long pc)
+{
+#ifdef CONFIG_DYNAMIC_FTRACE
+ return pc == (unsigned long)ftrace_call + LOONGARCH_INSN_SIZE;
+#else
+ return false;
+#endif
+}
+
+static inline bool unwind_state_fixup(struct unwind_state *state)
+{
+ if (!fix_exceptions(state->pc) && !fix_ftrace(state->pc))
+ return false;
+ state->reset = true;
+ return true;
}
static unsigned long get_return_address(struct unwind_state *state)
@@ -44,14 +123,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
if (state->sp >= info->end || state->sp < info->begin)
return false;
- if (state->is_ftrace) {
- /*
- * As we meet ftrace_regs_entry, reset first flag like first doing
- * tracing. Prologue analysis will stop soon because PC is at entry.
- */
+ if (state->reset) {
regs = (struct pt_regs *)state->sp;
state->first = true;
- state->is_ftrace = false;
+ state->reset = false;
state->pc = regs->csr_era;
state->ra = regs->regs[1];
state->sp = regs->regs[3];
@@ -116,8 +191,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
out:
state->first = false;
- unwind_state_fixup(state);
- return !!__kernel_text_address(state->pc);
+ return unwind_state_fixup(state) || __kernel_text_address(state->pc);
}
static void start(struct unwind_state *state, struct task_struct *task,
diff --git a/arch/loongarch/mm/tlb.c b/arch/loongarch/mm/tlb.c
index da3681f131c8..8bad6b0cff59 100644
--- a/arch/loongarch/mm/tlb.c
+++ b/arch/loongarch/mm/tlb.c
@@ -251,7 +251,7 @@ static void output_pgtable_bits_defines(void)
}
#ifdef CONFIG_NUMA
-static unsigned long pcpu_handlers[NR_CPUS];
+unsigned long pcpu_handlers[NR_CPUS];
#endif
extern long exception_handlers[VECSIZE * 128 / sizeof(long)];
--
2.34.3
^ permalink raw reply related [flat|nested] 9+ messages in thread