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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 | // SPDX-License-Identifier: GPL-2.0 // Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. #include <linux/perf_event.h> #include <linux/uaccess.h> /* Kernel callchain */ struct stackframe { unsigned long fp; unsigned long lr; }; static int unwind_frame_kernel(struct stackframe *frame) { unsigned long low = (unsigned long)task_stack_page(current); unsigned long high = low + THREAD_SIZE; if (unlikely(frame->fp < low || frame->fp > high)) return -EPERM; if (kstack_end((void *)frame->fp) || frame->fp & 0x3) return -EPERM; *frame = *(struct stackframe *)frame->fp; if (__kernel_text_address(frame->lr)) { int graph = 0; frame->lr = ftrace_graph_ret_addr(NULL, &graph, frame->lr, NULL); } return 0; } static void notrace walk_stackframe(struct stackframe *fr, struct perf_callchain_entry_ctx *entry) { do { perf_callchain_store(entry, fr->lr); } while (unwind_frame_kernel(fr) >= 0); } /* * Get the return address for a single stackframe and return a pointer to the * next frame tail. */ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, unsigned long fp, unsigned long reg_lr) { struct stackframe buftail; unsigned long lr = 0; unsigned long __user *user_frame_tail = (unsigned long __user *)fp; /* Check accessibility of one struct frame_tail beyond */ if (!access_ok(user_frame_tail, sizeof(buftail))) return 0; if (__copy_from_user_inatomic(&buftail, user_frame_tail, sizeof(buftail))) return 0; if (reg_lr != 0) lr = reg_lr; else lr = buftail.lr; fp = buftail.fp; perf_callchain_store(entry, lr); return fp; } /* * This will be called when the target is in user mode * This function will only be called when we use * "PERF_SAMPLE_CALLCHAIN" in * kernel/events/core.c:perf_prepare_sample() * * How to trigger perf_callchain_[user/kernel] : * $ perf record -e cpu-clock --call-graph fp ./program * $ perf report --call-graph * * On C-SKY platform, the program being sampled and the C library * need to be compiled with * -mbacktrace, otherwise the user * stack will not contain function frame. */ void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); unsigned long fp = 0; /* C-SKY does not support virtualization. */ if (guest_cbs && guest_cbs->is_in_guest()) return; fp = regs->regs[4]; perf_callchain_store(entry, regs->pc); /* * While backtrace from leaf function, lr is normally * not saved inside frame on C-SKY, so get lr from pt_regs * at the sample point. However, lr value can be incorrect if * lr is used as temp register */ fp = user_backtrace(entry, fp, regs->lr); while (fp && !(fp & 0x3) && entry->nr < entry->max_stack) fp = user_backtrace(entry, fp, 0); } void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) { struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs(); struct stackframe fr; /* C-SKY does not support virtualization. */ if (guest_cbs && guest_cbs->is_in_guest()) { pr_warn("C-SKY does not support perf in guest mode!"); return; } fr.fp = regs->regs[4]; fr.lr = regs->lr; walk_stackframe(&fr, entry); } |