diff options
author | Qing Zhang <zhangqing@loongson.cn> | 2022-08-06 11:10:03 +0300 |
---|---|---|
committer | Huacai Chen <chenhuacai@loongson.cn> | 2022-08-12 08:10:11 +0300 |
commit | 49aef111e2dae176a7708b532118f33f24289248 (patch) | |
tree | 394ff32e5dba1e22ebac5015fe3164e7ed2e8a77 | |
parent | 49232773d8233ed70c4998851bc84e465fc1c788 (diff) |
LoongArch: Add prologue unwinder support
It unwind the stack frame based on prologue code analyze.
CONFIG_KALLSYMS is needed, at least the address and length
of each function.
Three stages when we do unwind,
1) unwind_start(), the prapare of unwinding, fill unwind_state.
2) unwind_done(), judge whether the unwind process is finished or not.
3) unwind_next_frame(), unwind the next frame.
Dividing unwinder helps to add new unwinders in the future, e.g.:
unwinder_frame, unwinder_orc, .etc.
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
-rw-r--r-- | arch/loongarch/Kconfig.debug | 20 | ||||
-rw-r--r-- | arch/loongarch/include/asm/inst.h | 52 | ||||
-rw-r--r-- | arch/loongarch/include/asm/unwind.h | 8 | ||||
-rw-r--r-- | arch/loongarch/kernel/Makefile | 1 | ||||
-rw-r--r-- | arch/loongarch/kernel/traps.c | 3 | ||||
-rw-r--r-- | arch/loongarch/kernel/unwind_prologue.c | 176 |
6 files changed, 259 insertions, 1 deletions
diff --git a/arch/loongarch/Kconfig.debug b/arch/loongarch/Kconfig.debug index 68634d4fa27b..8d36aab53008 100644 --- a/arch/loongarch/Kconfig.debug +++ b/arch/loongarch/Kconfig.debug @@ -1,3 +1,11 @@ +choice + prompt "Choose kernel unwinder" + default UNWINDER_PROLOGUE if KALLSYMS + help + This determines which method will be used for unwinding kernel stack + traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, + lockdep, and more. + config UNWINDER_GUESS bool "Guess unwinder" help @@ -7,3 +15,15 @@ config UNWINDER_GUESS While this option often produces false positives, it can still be useful in many cases. + +config UNWINDER_PROLOGUE + bool "Prologue unwinder" + depends on KALLSYMS + help + This option enables the "prologue" unwinder for unwinding kernel stack + traces. It unwind the stack frame based on prologue code analyze. Symbol + information is needed, at least the address and length of each function. + Some of the addresses it reports may be incorrect (but better than the + Guess unwinder). + +endchoice diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h index 575d1bb66ffb..7b07cbb3188c 100644 --- a/arch/loongarch/include/asm/inst.h +++ b/arch/loongarch/include/asm/inst.h @@ -23,12 +23,33 @@ enum reg1i20_op { lu32id_op = 0x0b, }; +enum reg1i21_op { + beqz_op = 0x10, + bnez_op = 0x11, +}; + enum reg2i12_op { + addiw_op = 0x0a, + addid_op = 0x0b, lu52id_op = 0x0c, + ldb_op = 0xa0, + ldh_op = 0xa1, + ldw_op = 0xa2, + ldd_op = 0xa3, + stb_op = 0xa4, + sth_op = 0xa5, + stw_op = 0xa6, + std_op = 0xa7, }; enum reg2i16_op { jirl_op = 0x13, + beq_op = 0x16, + bne_op = 0x17, + blt_op = 0x18, + bge_op = 0x19, + bltu_op = 0x1a, + bgeu_op = 0x1b, }; struct reg0i26_format { @@ -110,6 +131,37 @@ enum loongarch_gpr { LOONGARCH_GPR_MAX }; +#define is_imm12_negative(val) is_imm_negative(val, 12) + +static inline bool is_imm_negative(unsigned long val, unsigned int bit) +{ + return val & (1UL << (bit - 1)); +} + +static inline bool is_branch_ins(union loongarch_instruction *ip) +{ + return ip->reg1i21_format.opcode >= beqz_op && + ip->reg1i21_format.opcode <= bgeu_op; +} + +static inline bool is_ra_save_ins(union loongarch_instruction *ip) +{ + /* st.d $ra, $sp, offset */ + return ip->reg2i12_format.opcode == std_op && + ip->reg2i12_format.rj == LOONGARCH_GPR_SP && + ip->reg2i12_format.rd == LOONGARCH_GPR_RA && + !is_imm12_negative(ip->reg2i12_format.immediate); +} + +static inline bool is_stack_alloc_ins(union loongarch_instruction *ip) +{ + /* addi.d $sp, $sp, -imm */ + return ip->reg2i12_format.opcode == addid_op && + ip->reg2i12_format.rj == LOONGARCH_GPR_SP && + ip->reg2i12_format.rd == LOONGARCH_GPR_SP && + is_imm12_negative(ip->reg2i12_format.immediate); +} + u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm); u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm); u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest); diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h index 206fcbe24c0a..6af4718bdf01 100644 --- a/arch/loongarch/include/asm/unwind.h +++ b/arch/loongarch/include/asm/unwind.h @@ -11,11 +11,17 @@ #include <asm/stacktrace.h> +enum unwinder_type { + UNWINDER_GUESS, + UNWINDER_PROLOGUE, +}; + struct unwind_state { + char type; /* UNWINDER_XXX */ struct stack_info stack_info; struct task_struct *task; bool first, error; - unsigned long sp, pc; + unsigned long sp, pc, ra; }; void unwind_start(struct unwind_state *state, diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile index c5fa4adb23b6..918600e7b30f 100644 --- a/arch/loongarch/kernel/Makefile +++ b/arch/loongarch/kernel/Makefile @@ -23,5 +23,6 @@ obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_NUMA) += numa.o obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o +obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS) diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c index f65fdf90d29e..aa1c95aaf595 100644 --- a/arch/loongarch/kernel/traps.c +++ b/arch/loongarch/kernel/traps.c @@ -71,6 +71,9 @@ 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_prologue.c b/arch/loongarch/kernel/unwind_prologue.c new file mode 100644 index 000000000000..b206d9159205 --- /dev/null +++ b/arch/loongarch/kernel/unwind_prologue.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2022 Loongson Technology Corporation Limited + */ +#include <linux/kallsyms.h> + +#include <asm/inst.h> +#include <asm/ptrace.h> +#include <asm/unwind.h> + +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); + +} +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); + if (__kernel_text_address(addr)) + return true; + } + + return false; +} + +static bool unwind_by_prologue(struct unwind_state *state) +{ + struct stack_info *info = &state->stack_info; + union loongarch_instruction *ip, *ip_end; + unsigned long frame_size = 0, frame_ra = -1; + unsigned long size, offset, pc = state->pc; + + if (state->sp >= info->end || state->sp < info->begin) + return false; + + if (!kallsyms_lookup_size_offset(pc, &size, &offset)) + return false; + + ip = (union loongarch_instruction *)(pc - offset); + ip_end = (union loongarch_instruction *)pc; + + while (ip < ip_end) { + if (is_stack_alloc_ins(ip)) { + frame_size = (1 << 12) - ip->reg2i12_format.immediate; + ip++; + break; + } + ip++; + } + + if (!frame_size) { + if (state->first) + goto first; + + return false; + } + + while (ip < ip_end) { + if (is_ra_save_ins(ip)) { + frame_ra = ip->reg2i12_format.immediate; + break; + } + if (is_branch_ins(ip)) + break; + ip++; + } + + if (frame_ra < 0) { + if (state->first) { + state->sp = state->sp + frame_size; + goto first; + } + return false; + } + + if (state->first) + state->first = false; + + state->pc = *(unsigned long *)(state->sp + frame_ra); + state->sp = state->sp + frame_size; + return !!__kernel_text_address(state->pc); + +first: + state->first = false; + if (state->pc == state->ra) + return false; + + state->pc = state->ra; + + return !!__kernel_text_address(state->ra); +} + +void unwind_start(struct unwind_state *state, struct task_struct *task, + struct pt_regs *regs) +{ + memset(state, 0, sizeof(*state)); + + if (regs && __kernel_text_address(regs->csr_era)) { + state->pc = regs->csr_era; + state->sp = regs->regs[3]; + state->ra = regs->regs[1]; + state->type = UNWINDER_PROLOGUE; + } + + state->task = task; + state->first = true; + + 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) +{ + 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)) + return true; + + 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; + + state->pc = pc; + state->sp = regs->regs[3]; + state->ra = regs->regs[1]; + state->first = true; + get_stack_info(state->sp, state->task, info); + + return true; + } + } + + state->sp = info->next_sp; + + } while (!get_stack_info(state->sp, state->task, info)); + + return false; +} +EXPORT_SYMBOL_GPL(unwind_next_frame); |