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Date: Thu, 29 Dec 2022 14:15:16 +0800 From: Jinyang He <hejinyang@...ngson.cn> To: Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>, Qing Zhang <zhangqing@...ngson.cn> Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, Mark Rutland <mark.rutland@....com> Subject: [PATCH v2 5/6] LoongArch: Add generic ex-handler unwind in prologue unwinder 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@...ngson.cn> Signed-off-by: Jinyang He <hejinyang@...ngson.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
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