diff options
Diffstat (limited to 'arch/x86/events/core.c')
| -rw-r--r-- | arch/x86/events/core.c | 85 |
1 files changed, 75 insertions, 10 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 12f2a0c14d33..65ab6460aed4 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -41,6 +41,8 @@ #include <asm/desc.h> #include <asm/ldt.h> #include <asm/unwind.h> +#include <asm/uprobes.h> +#include <asm/ibt.h> #include "perf_event.h" @@ -1520,20 +1522,23 @@ static void x86_pmu_start(struct perf_event *event, int flags) void perf_event_print_debug(void) { u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left, fixed; + unsigned long *cntr_mask, *fixed_cntr_mask; + struct event_constraint *pebs_constraints; + struct cpu_hw_events *cpuc; u64 pebs, debugctl; - int cpu = smp_processor_id(); - struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu); - unsigned long *cntr_mask = hybrid(cpuc->pmu, cntr_mask); - unsigned long *fixed_cntr_mask = hybrid(cpuc->pmu, fixed_cntr_mask); - struct event_constraint *pebs_constraints = hybrid(cpuc->pmu, pebs_constraints); - unsigned long flags; - int idx; + int cpu, idx; + + guard(irqsave)(); + + cpu = smp_processor_id(); + cpuc = &per_cpu(cpu_hw_events, cpu); + cntr_mask = hybrid(cpuc->pmu, cntr_mask); + fixed_cntr_mask = hybrid(cpuc->pmu, fixed_cntr_mask); + pebs_constraints = hybrid(cpuc->pmu, pebs_constraints); if (!*(u64 *)cntr_mask) return; - local_irq_save(flags); - if (x86_pmu.version >= 2) { rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl); rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status); @@ -1577,7 +1582,6 @@ void perf_event_print_debug(void) pr_info("CPU#%d: fixed-PMC%d count: %016llx\n", cpu, idx, pmc_count); } - local_irq_restore(flags); } void x86_pmu_stop(struct perf_event *event, int flags) @@ -2814,6 +2818,46 @@ static unsigned long get_segment_base(unsigned int segment) return get_desc_base(desc); } +#ifdef CONFIG_UPROBES +/* + * Heuristic-based check if uprobe is installed at the function entry. + * + * Under assumption of user code being compiled with frame pointers, + * `push %rbp/%ebp` is a good indicator that we indeed are. + * + * Similarly, `endbr64` (assuming 64-bit mode) is also a common pattern. + * If we get this wrong, captured stack trace might have one extra bogus + * entry, but the rest of stack trace will still be meaningful. + */ +static bool is_uprobe_at_func_entry(struct pt_regs *regs) +{ + struct arch_uprobe *auprobe; + + if (!current->utask) + return false; + + auprobe = current->utask->auprobe; + if (!auprobe) + return false; + + /* push %rbp/%ebp */ + if (auprobe->insn[0] == 0x55) + return true; + + /* endbr64 (64-bit only) */ + if (user_64bit_mode(regs) && is_endbr(*(u32 *)auprobe->insn)) + return true; + + return false; +} + +#else +static bool is_uprobe_at_func_entry(struct pt_regs *regs) +{ + return false; +} +#endif /* CONFIG_UPROBES */ + #ifdef CONFIG_IA32_EMULATION #include <linux/compat.h> @@ -2825,6 +2869,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent unsigned long ss_base, cs_base; struct stack_frame_ia32 frame; const struct stack_frame_ia32 __user *fp; + u32 ret_addr; if (user_64bit_mode(regs)) return 0; @@ -2834,6 +2879,12 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent fp = compat_ptr(ss_base + regs->bp); pagefault_disable(); + + /* see perf_callchain_user() below for why we do this */ + if (is_uprobe_at_func_entry(regs) && + !get_user(ret_addr, (const u32 __user *)regs->sp)) + perf_callchain_store(entry, ret_addr); + while (entry->nr < entry->max_stack) { if (!valid_user_frame(fp, sizeof(frame))) break; @@ -2862,6 +2913,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs { struct stack_frame frame; const struct stack_frame __user *fp; + unsigned long ret_addr; if (perf_guest_state()) { /* TODO: We don't support guest os callchain now */ @@ -2885,6 +2937,19 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs return; pagefault_disable(); + + /* + * If we are called from uprobe handler, and we are indeed at the very + * entry to user function (which is normally a `push %rbp` instruction, + * under assumption of application being compiled with frame pointers), + * we should read return address from *regs->sp before proceeding + * to follow frame pointers, otherwise we'll skip immediate caller + * as %rbp is not yet setup. + */ + if (is_uprobe_at_func_entry(regs) && + !get_user(ret_addr, (const unsigned long __user *)regs->sp)) + perf_callchain_store(entry, ret_addr); + while (entry->nr < entry->max_stack) { if (!valid_user_frame(fp, sizeof(frame))) break; |