Messages in this thread Patch in this message | | | Subject | Re: [PATCH 6/6] LoongArch: Add generic ex-handler unwind in prologue unwinder | From | Qing Zhang <> | Date | Thu, 15 Dec 2022 20:04:54 +0800 |
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Hi, Jinyang
On 2022/12/15 下午12:01, Jinyang He wrote: > 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@loongson.cn> > Signed-off-by: Jinyang He <hejinyang@loongson.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(-) > The others look good to me, but there is still a small problem: When I tested hw_breakpoint.ko with prologue unwinder, sometimes output address [<9000000100302724>] 0x9000000100302724, eg: CPU: 3 PID: 0 But some processes are normal, eg: CPU: 0 PID: 0
[27.655549] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 6.1.0-rc8 #9 [27.655552] Hardware name: Loongson Loongson-3A5000-7A1000-1w-A2101/ Loongson-LS3A5000-7A1000-1w-A2101, BIOS vUDK2018-LoongArch-V2.0.pre-beta8 06/15/2022
[27.655604]... [27.655606] Call Trace: [27.655607] [<9000000000222f88>] show_stack+0x60/0x184 [27.655613] [<90000000010e9b8c>] dump_stack_lvl+0x60/0x88 [27.655618] [] sample_hbp_handler+0x30/0x4c [data_breakpoint] [27.655626] [<900000000037c8a0>] __perf_event_overflow+0x84/0x26c [27.655629] [<900000000038980c>] perf_bp_event+0xc0/0xc8 [27.655633] [<900000000022e3bc>] watchpoint_handler+0x54/0x88 [27.655637] [<90000000010ea2f8>] do_watch+0x30/0x48 [27.655640] [<9000000100302724>] 0x9000000100302724 // Not natural [27.655642] [<9000000000ab4cbc>] add_interrupt_randomness+0x60/0xbc [27.655646] [<90000000002a0fa0>] handle_irq_event_percpu+0x28/0x70 [27.655650] [<90000000002a6f9c>] handle_percpu_irq+0x54/0x88 [27.655652] [<90000000002a025c>] generic_handle_domain_irq+0x28/0x40 [27.655655] [<9000000000995458>] handle_cpu_irq+0x68/0xa4 [27.655658] [<90000000010ea8dc>] handle_loongarch_irq+0x34/0x4c [27.655661] [<90000000010ea974>] do_vint+0x80/0xb4 [27.655664] [<90000000002216a0>] __arch_cpu_idle+0x20/0x24 [27.655667] [<90000000010f8178>] default_idle_call+0x30/0x58 [27.655670] [<90000000002825cc>] do_idle+0xb4/0x118 [27.655674] [<900000000028281c>] cpu_startup_entry+0x20/0x24 [27.655677] [<900000000022b198>] start_secondary+0x9c/0xa4 [27.655679] [<90000000010eb124>] smpboot_entry+0x60/0x64
[27.658940] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.0-rc8 #9 ... [28.229978] Call Trace: [28.229979] [<9000000000222f88>] show_stack+0x60/0x184 [28.237503] [<90000000010e9b8c>] dump_stack_lvl+0x60/0x88 [28.242866] [] sample_hbp_handler+0x30/0x4c [data_breakpoint] [28.250132] [<900000000037c8a0>] __perf_event_overflow+0x84/0x26c [28.256186] [<900000000038980c>] perf_bp_event+0xc0/0xc8 [28.261462] [<900000000022e3bc>] watchpoint_handler+0x54/0x88 [28.267170] [<90000000010ea2f8>] do_watch+0x30/0x48 [28.272013] [<90000000017d2724>] exception_handlers+0x2724/0x1000 //... [28.278155] [<9000000000ab4cbc>] add_interrupt_randomness+0x60/0xbc [28.284381] [<90000000002a0fa0>] handle_irq_event_percpu+0x28/0x70 [28.290520] [<90000000002a6f9c>] handle_percpu_irq+0x54/0x88 [28.296140] [<90000000002a025c>] generic_handle_domain_irq+0x28/0x40 [28.302452] [<9000000000995458>] handle_cpu_irq+0x68/0xa4 [28.307813] [<90000000010ea8dc>] handle_loongarch_irq+0x34/0x4c [28.313693] [<90000000010ea974>] do_vint+0x80/0xb4 [28.318450] [<90000000002216a0>] __arch_cpu_idle+0x20/0x24 [28.323897] [<90000000010f8178>] default_idle_call+0x30/0x58 [28.329518] [<90000000002825cc>] do_idle+0xb4/0x118 [28.334361] [<900000000028281c>] cpu_startup_entry+0x20/0x24 [28.339982] [<90000000010ec0dc>] kernel_init+0x0/0x110 [28.345085] [<90000000011106f8>] arch_post_acpi_subsys_init+0x0/0x4
Maybe sometimes assembly kallsyms is not recognized, let me think...
Thanks, -Qing
> diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h > index a16aff1d086a..c02cb3b39fe2 100644 > --- a/arch/loongarch/include/asm/unwind.h > +++ b/arch/loongarch/include/asm/unwind.h > @@ -24,7 +24,7 @@ struct unwind_state { > char type; /* UNWINDER_XXX */ > 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 441641227c10..c34bb035ac56 100644 > --- a/arch/loongarch/kernel/unwind_prologue.c > +++ b/arch/loongarch/kernel/unwind_prologue.c > @@ -2,23 +2,102 @@ > /* > * 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 const struct unwinder_ops *guard_unwinder = &unwinder_guess; > > -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) > @@ -46,14 +125,10 @@ 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]; > @@ -118,8 +193,7 @@ 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 int raw_show_trace; > 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)]; > >
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