Commit 49aef111 authored by Qing Zhang's avatar Qing Zhang Committed by Huacai Chen

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: default avatarQing Zhang <zhangqing@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 49232773
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 config UNWINDER_GUESS
bool "Guess unwinder" bool "Guess unwinder"
help help
...@@ -7,3 +15,15 @@ config UNWINDER_GUESS ...@@ -7,3 +15,15 @@ config UNWINDER_GUESS
While this option often produces false positives, it can still be While this option often produces false positives, it can still be
useful in many cases. 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
...@@ -23,12 +23,33 @@ enum reg1i20_op { ...@@ -23,12 +23,33 @@ enum reg1i20_op {
lu32id_op = 0x0b, lu32id_op = 0x0b,
}; };
enum reg1i21_op {
beqz_op = 0x10,
bnez_op = 0x11,
};
enum reg2i12_op { enum reg2i12_op {
addiw_op = 0x0a,
addid_op = 0x0b,
lu52id_op = 0x0c, 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 { enum reg2i16_op {
jirl_op = 0x13, jirl_op = 0x13,
beq_op = 0x16,
bne_op = 0x17,
blt_op = 0x18,
bge_op = 0x19,
bltu_op = 0x1a,
bgeu_op = 0x1b,
}; };
struct reg0i26_format { struct reg0i26_format {
...@@ -110,6 +131,37 @@ enum loongarch_gpr { ...@@ -110,6 +131,37 @@ enum loongarch_gpr {
LOONGARCH_GPR_MAX 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, $sp, -imm */
return ip->reg2i12_format.opcode == addid_op &&
ip->reg2i12_format.rj == LOONGARCH_GPR_SP &&
ip->reg2i12_format.rd == LOONGARCH_GPR_SP &&
is_imm12_negative(ip->reg2i12_format.immediate);
}
u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm); u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm);
u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm); u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest); u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest);
......
...@@ -11,11 +11,17 @@ ...@@ -11,11 +11,17 @@
#include <asm/stacktrace.h> #include <asm/stacktrace.h>
enum unwinder_type {
UNWINDER_GUESS,
UNWINDER_PROLOGUE,
};
struct unwind_state { struct unwind_state {
char type; /* UNWINDER_XXX */
struct stack_info stack_info; struct stack_info stack_info;
struct task_struct *task; struct task_struct *task;
bool first, error; bool first, error;
unsigned long sp, pc; unsigned long sp, pc, ra;
}; };
void unwind_start(struct unwind_state *state, void unwind_start(struct unwind_state *state,
......
...@@ -23,5 +23,6 @@ obj-$(CONFIG_SMP) += smp.o ...@@ -23,5 +23,6 @@ obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_NUMA) += numa.o obj-$(CONFIG_NUMA) += numa.o
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS) CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS)
...@@ -71,6 +71,9 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs, ...@@ -71,6 +71,9 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
if (!task) if (!task)
task = current; task = current;
if (user_mode(regs))
state.type = UNWINDER_GUESS;
printk("%sCall Trace:", loglvl); printk("%sCall Trace:", loglvl);
for (unwind_start(&state, task, pregs); for (unwind_start(&state, task, pregs);
!unwind_done(&state); unwind_next_frame(&state)) { !unwind_done(&state); unwind_next_frame(&state)) {
......
// 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);
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