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Date: Tue, 20 Sep 2022 23:12:00 +0800 From: Chen Zhongjin <chenzhongjin@...wei.com> To: <linux-kernel@...r.kernel.org>, <linux-riscv@...ts.infradead.org>, <linux-perf-users@...r.kernel.org> CC: <paul.walmsley@...ive.com>, <palmer@...belt.com>, <aou@...s.berkeley.edu>, <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>, <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>, <namhyung@...nel.org>, <jolsa@...nel.org>, <guoren@...nel.org>, <nsaenzju@...hat.com>, <frederic@...nel.org>, <changbin.du@...el.com>, <vincent.chen@...ive.com>, <ardb@...nel.org>, <mhiramat@...nel.org>, <rostedt@...dmis.org>, <keescook@...omium.org>, <catalin.marinas@....com>, <chenzhongjin@...wei.com> Subject: [PATCH -next 5/7] riscv: stacktrace: Implement stacktrace for irq After adding encoded fp onto stack to record pt_regs, now the unwinder have ability to unwind frame through irq. There is two steps to unwind irq frame and the interrupted frame: 1. When there is an encoded fp on stack, we can get the pt_regs and unwind frame by (regs->epc) and (regs->s0). 2. To unwind the interrupted frame, there is two possibilities, we can determine the situation by checking whether the value in frame->ra position is a fp value. If there is a fp in ra position: We are inside a leaf frame and there is only fp on ra position. Get fp from ra position and get next pc from pt_regs. Else: Just get fp and next pc from stack frame. Stacktrace before this patch: Call Trace: ... [<ffffffff800aa692>] __flush_smp_call_function_queue+0xde/0x1fa [<ffffffff800ab404>] generic_smp_call_function_single_interrupt+0x22/0x2a [<ffffffff800077b2>] handle_IPI+0xaa/0x108 [<ffffffff803f827e>] riscv_intc_irq+0x56/0x6e [<ffffffff808d94b6>] generic_handle_arch_irq+0x4c/0x76 [<ffffffff80003ad0>] ret_from_exception+0x0/0xc Stacktrace after this patch: Call Trace: ... [<ffffffff800aa6da>] __flush_smp_call_function_queue+0xde/0x1fa [<ffffffff800ab44c>] generic_smp_call_function_single_interrupt+0x22/0x2a [<ffffffff800077fa>] handle_IPI+0xaa/0x108 [<ffffffff803f82c6>] riscv_intc_irq+0x56/0x6e [<ffffffff808d94fe>] generic_handle_arch_irq+0x4c/0x76 [<ffffffff80003ad0>] ret_from_exception+0x0/0xc + [<ffffffff80003d52>] arch_cpu_idle+0x22/0x28 + [<ffffffff808e23a8>] default_idle_call+0x44/0xee + [<ffffffff80056ece>] do_idle+0x116/0x126 + [<ffffffff8005706e>] cpu_startup_entry+0x36/0x38 + [<ffffffff808d99ae>] kernel_init+0x0/0x15a + [<ffffffff80a007a0>] arch_post_acpi_subsys_init+0x0/0x38 + [<ffffffff80a0100c>] start_kernel+0x7c4/0x7f2 Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com> --- arch/riscv/kernel/stacktrace.c | 45 ++++++++++++++++++++++++++++------ 1 file changed, 38 insertions(+), 7 deletions(-) diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index e84e21868a3e..976dc298ab3b 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -16,29 +16,60 @@ #ifdef CONFIG_FRAME_POINTER +static struct pt_regs *decode_frame_pointer(unsigned long fp) +{ + if (!(fp & 0x1)) + return NULL; + + return (struct pt_regs *)(fp & ~0x1); +} + static int notrace unwind_next(struct unwind_state *state) { unsigned long low, high, fp; struct stackframe *frame; + struct pt_regs *regs; - fp = state->fp; + regs = decode_frame_pointer(state->fp); /* Validate frame pointer */ - low = state->sp + sizeof(struct stackframe); + if (regs) { + if user_mode(regs) + return -1; + + fp = (unsigned long)regs; + low = state->sp; + } else { + fp = state->fp; + low = state->sp + sizeof(struct stackframe); + } high = ALIGN(low, THREAD_SIZE); if (fp < low || fp > high || fp & 0x7) return -EINVAL; - /* Unwind stack frame */ frame = (struct stackframe *)fp - 1; state->sp = fp; - if (state->regs && state->regs->epc == state->pc && - fp & 0x7) { - state->fp = frame->ra; - state->pc = state->regs->ra; + if (regs) { + /* Unwind from irq to interrupted function */ + state->fp = regs->s0; + state->pc = regs->epc; + state->regs = regs; + } else if (state->regs && state->regs->epc == state->pc) { + /* Unwind from interrupted function to caller*/ + if (frame->ra < low || frame->ra > high) { + /* normal function */ + state->fp = frame->fp; + state->pc = frame->ra; + } else { + /* leaf function */ + state->fp = frame->ra; + state->pc = state->regs->ra; + } + state->regs = NULL; } else { + /* Unwind from normal stack frame */ state->fp = frame->fp; state->pc = ftrace_graph_ret_addr(current, NULL, frame->ra, (unsigned long *)fp - 1); -- 2.17.1
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