From 93a4fa622eb061f75f87f0cf9609ab4e69c67d01 Mon Sep 17 00:00:00 2001 From: Qing Zhang Date: Sat, 6 Aug 2022 16:10:04 +0800 Subject: [PATCH] LoongArch: Add STACKTRACE support 1. Use common arch_stack_walk() infrastructure to avoid duplicated code and avoid taking care of the stack storage and filtering. 2. Add sched_ra (means sched return address) and sched_cfa (means sched call frame address) to thread_info, and store them in switch_to(). 3. Add __get_wchan() implementation. Now we can print the process stack and wait channel by cat /proc/*/stack and /proc/*/wchan. Signed-off-by: Qing Zhang Signed-off-by: Huacai Chen --- arch/loongarch/Kconfig | 5 ++++ arch/loongarch/include/asm/processor.h | 9 +++++++ arch/loongarch/include/asm/switch_to.h | 14 ++++++---- arch/loongarch/kernel/Makefile | 1 + arch/loongarch/kernel/asm-offsets.c | 2 ++ arch/loongarch/kernel/process.c | 29 +++++++++++++++++++- arch/loongarch/kernel/stacktrace.c | 37 ++++++++++++++++++++++++++ arch/loongarch/kernel/switch.S | 2 ++ 8 files changed, 93 insertions(+), 6 deletions(-) create mode 100644 arch/loongarch/kernel/stacktrace.c diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 5b4f7bdf69fa..947cb633744b 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -42,6 +42,7 @@ config LOONGARCH select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO select ARCH_SPARSEMEM_ENABLE + select ARCH_STACKWALK select ARCH_SUPPORTS_ACPI select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_HUGETLBFS @@ -151,6 +152,10 @@ config LOCKDEP_SUPPORT bool default y +config STACKTRACE_SUPPORT + bool + default y + # MACH_LOONGSON32 and MACH_LOONGSON64 are delibrately carried over from the # MIPS Loongson code, to preserve Loongson-specific code paths in drivers that # are shared between architectures, and specifically expecting the symbols. diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h index 57ec45aa078e..1c4b4308378d 100644 --- a/arch/loongarch/include/asm/processor.h +++ b/arch/loongarch/include/asm/processor.h @@ -101,6 +101,10 @@ struct thread_struct { unsigned long reg23, reg24, reg25, reg26; /* s0-s3 */ unsigned long reg27, reg28, reg29, reg30, reg31; /* s4-s8 */ + /* __schedule() return address / call frame address */ + unsigned long sched_ra; + unsigned long sched_cfa; + /* CSR registers */ unsigned long csr_prmd; unsigned long csr_crmd; @@ -129,6 +133,9 @@ struct thread_struct { struct loongarch_fpu fpu FPU_ALIGN; }; +#define thread_saved_ra(tsk) (tsk->thread.sched_ra) +#define thread_saved_fp(tsk) (tsk->thread.sched_cfa) + #define INIT_THREAD { \ /* \ * Main processor registers \ @@ -145,6 +152,8 @@ struct thread_struct { .reg29 = 0, \ .reg30 = 0, \ .reg31 = 0, \ + .sched_ra = 0, \ + .sched_cfa = 0, \ .csr_crmd = 0, \ .csr_prmd = 0, \ .csr_euen = 0, \ diff --git a/arch/loongarch/include/asm/switch_to.h b/arch/loongarch/include/asm/switch_to.h index 2a8d04375574..43a5ab162d38 100644 --- a/arch/loongarch/include/asm/switch_to.h +++ b/arch/loongarch/include/asm/switch_to.h @@ -15,12 +15,15 @@ struct task_struct; * @prev: The task previously executed. * @next: The task to begin executing. * @next_ti: task_thread_info(next). + * @sched_ra: __schedule return address. + * @sched_cfa: __schedule call frame address. * * This function is used whilst scheduling to save the context of prev & load * the context of next. Returns prev. */ extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev, - struct task_struct *next, struct thread_info *next_ti); + struct task_struct *next, struct thread_info *next_ti, + void *sched_ra, void *sched_cfa); /* * For newly created kernel threads switch_to() will return to @@ -28,10 +31,11 @@ extern asmlinkage struct task_struct *__switch_to(struct task_struct *prev, * That is, everything following __switch_to() will be skipped for new threads. * So everything that matters to new threads should be placed before __switch_to(). */ -#define switch_to(prev, next, last) \ -do { \ - lose_fpu_inatomic(1, prev); \ - (last) = __switch_to(prev, next, task_thread_info(next)); \ +#define switch_to(prev, next, last) \ +do { \ + lose_fpu_inatomic(1, prev); \ + (last) = __switch_to(prev, next, task_thread_info(next), \ + __builtin_return_address(0), __builtin_frame_address(0)); \ } while (0) #endif /* _ASM_SWITCH_TO_H */ diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile index 918600e7b30f..e5be17009fe8 100644 --- a/arch/loongarch/kernel/Makefile +++ b/arch/loongarch/kernel/Makefile @@ -15,6 +15,7 @@ obj-$(CONFIG_EFI) += efi.o obj-$(CONFIG_CPU_HAS_FPU) += fpu.o obj-$(CONFIG_MODULES) += module.o module-sections.o +obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-$(CONFIG_PROC_FS) += proc.o diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c index 20cd9e16a95a..eb350f3ffae5 100644 --- a/arch/loongarch/kernel/asm-offsets.c +++ b/arch/loongarch/kernel/asm-offsets.c @@ -103,6 +103,8 @@ void output_thread_defines(void) OFFSET(THREAD_REG29, task_struct, thread.reg29); OFFSET(THREAD_REG30, task_struct, thread.reg30); OFFSET(THREAD_REG31, task_struct, thread.reg31); + OFFSET(THREAD_SCHED_RA, task_struct, thread.sched_ra); + OFFSET(THREAD_SCHED_CFA, task_struct, thread.sched_cfa); OFFSET(THREAD_CSRCRMD, task_struct, thread.csr_crmd); OFFSET(THREAD_CSRPRMD, task_struct, diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c index 839f0e963152..660492f064e7 100644 --- a/arch/loongarch/kernel/process.c +++ b/arch/loongarch/kernel/process.c @@ -135,6 +135,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) childregs = (struct pt_regs *) childksp - 1; /* Put the stack after the struct pt_regs. */ childksp = (unsigned long) childregs; + p->thread.sched_cfa = 0; p->thread.csr_euen = 0; p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD); p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD); @@ -145,6 +146,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.reg23 = (unsigned long)args->fn; p->thread.reg24 = (unsigned long)args->fn_arg; p->thread.reg01 = (unsigned long)ret_from_kernel_thread; + p->thread.sched_ra = (unsigned long)ret_from_kernel_thread; memset(childregs, 0, sizeof(struct pt_regs)); childregs->csr_euen = p->thread.csr_euen; childregs->csr_crmd = p->thread.csr_crmd; @@ -161,6 +163,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.reg03 = (unsigned long) childregs; p->thread.reg01 = (unsigned long) ret_from_fork; + p->thread.sched_ra = (unsigned long) ret_from_fork; /* * New tasks lose permission to use the fpu. This accelerates context @@ -181,7 +184,31 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) unsigned long __get_wchan(struct task_struct *task) { - return 0; + unsigned long pc; + 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)) { + pc = unwind_get_return_address(&state); + if (!pc) + break; + if (in_sched_functions(pc)) + continue; + break; + } + + put_task_stack(task); + + return pc; } bool in_irq_stack(unsigned long stack, struct stack_info *info) diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c new file mode 100644 index 000000000000..e690c1c769f2 --- /dev/null +++ b/arch/loongarch/kernel/stacktrace.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Stack trace management functions + * + * Copyright (C) 2022 Loongson Technology Corporation Limited + */ +#include +#include + +#include +#include + +void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, + struct task_struct *task, struct pt_regs *regs) +{ + unsigned long addr; + struct pt_regs dummyregs; + struct unwind_state state; + + regs = &dummyregs; + + if (task == current) { + regs->regs[3] = (unsigned long)__builtin_frame_address(0); + regs->csr_era = (unsigned long)__builtin_return_address(0); + } else { + regs->regs[3] = thread_saved_fp(task); + regs->csr_era = thread_saved_ra(task); + } + + regs->regs[1] = 0; + for (unwind_start(&state, task, regs); + !unwind_done(&state); unwind_next_frame(&state)) { + addr = unwind_get_return_address(&state); + if (!addr || !consume_entry(cookie, addr)) + break; + } +} diff --git a/arch/loongarch/kernel/switch.S b/arch/loongarch/kernel/switch.S index 37e84ac8ffc2..43ebbc3990f7 100644 --- a/arch/loongarch/kernel/switch.S +++ b/arch/loongarch/kernel/switch.S @@ -21,6 +21,8 @@ SYM_FUNC_START(__switch_to) cpu_save_nonscratch a0 stptr.d ra, a0, THREAD_REG01 + stptr.d a3, a0, THREAD_SCHED_RA + stptr.d a4, a0, THREAD_SCHED_CFA move tp, a2 cpu_restore_nonscratch a1 -- 2.20.1