Messages in this thread | | | Subject | Re: [PATCH 4/6] LoongArch: Strip guess_unwinder out from prologue_unwinder | From | Jinyang He <> | Date | Fri, 16 Dec 2022 09:40:24 +0800 |
| |
On 2022-12-15 17:15, Qing Zhang wrote:
> Hi, Jinyang > > On 2022/12/15 下午12:01, Jinyang He 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 | 22 ++++ >> arch/loongarch/kernel/Makefile | 3 +- >> arch/loongarch/kernel/unwind.c | 52 +++++++++ >> arch/loongarch/kernel/unwind_guess.c | 41 ++----- >> arch/loongarch/kernel/unwind_prologue.c | 135 +++++++++--------------- >> 5 files changed, 135 insertions(+), 118 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..a16aff1d086a 100644 >> --- a/arch/loongarch/include/asm/unwind.h >> +++ b/arch/loongarch/include/asm/unwind.h >> @@ -18,6 +18,8 @@ enum unwinder_type { >> UNWINDER_PROLOGUE, >> }; >> +struct unwinder_ops; >> + >> struct unwind_state { >> char type; /* UNWINDER_XXX */ >> struct stack_info stack_info; >> @@ -25,8 +27,22 @@ struct unwind_state { >> 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 +65,10 @@ 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/unwind.c >> b/arch/loongarch/kernel/unwind.c >> new file mode 100644 >> index 000000000000..568c6fe707d1 >> --- /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) { >> + 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 8ce32c37c587..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) { >> - 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_add(state, state->pc, state->sp); > > Do we need to unwind_graph_add again here? unwinder_guess and > unwind_prologue have already been done.
Hi, Qing
Sorry I don't what meanning here, as here is a delete line.
> >> - 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 d464c533c64f..9677e13c4b4c 100644 >> --- a/arch/loongarch/kernel/unwind_prologue.c >> +++ b/arch/loongarch/kernel/unwind_prologue.c >> @@ -9,6 +9,8 @@ >> #include <asm/ptrace.h> >> #include <asm/unwind.h> >> +static const struct unwinder_ops *guard_unwinder = &unwinder_guess; >> + >> static inline void unwind_state_fixup(struct unwind_state *state) >> { >> #ifdef CONFIG_DYNAMIC_FTRACE >> @@ -19,31 +21,19 @@ 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 +79,10 @@ 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 +100,7 @@ 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 +109,63 @@ 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) { >> - 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 guard unwinder. >> + */ >> + if (!__kernel_text_address(state->pc)) { >> + unwind_register_unwinder(state, guard_unwinder); > > Just add a comment here. Instead of using guard_unwinder, can we still > use guess_unwinder?
Yes, and I'll use '&guess_unwinder' in next version. And I'll drop unwind type in next version, too.
Thanks,
Jinyang
| |