1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
4 #include <linux/perf_event.h>
5 #include <linux/uaccess.h>
13 static int unwind_frame_kernel(struct stackframe *frame)
15 unsigned long low = (unsigned long)task_stack_page(current);
16 unsigned long high = low + THREAD_SIZE;
18 if (unlikely(frame->fp < low || frame->fp > high))
21 if (kstack_end((void *)frame->fp) || frame->fp & 0x3)
24 *frame = *(struct stackframe *)frame->fp;
26 if (__kernel_text_address(frame->lr)) {
29 frame->lr = ftrace_graph_ret_addr(NULL, &graph, frame->lr,
35 static void notrace walk_stackframe(struct stackframe *fr,
36 struct perf_callchain_entry_ctx *entry)
39 perf_callchain_store(entry, fr->lr);
40 } while (unwind_frame_kernel(fr) >= 0);
44 * Get the return address for a single stackframe and return a pointer to the
47 static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
48 unsigned long fp, unsigned long reg_lr)
50 struct stackframe buftail;
52 unsigned long *user_frame_tail = (unsigned long *)fp;
54 /* Check accessibility of one struct frame_tail beyond */
55 if (!access_ok(user_frame_tail, sizeof(buftail)))
57 if (__copy_from_user_inatomic(&buftail, user_frame_tail,
67 perf_callchain_store(entry, lr);
73 * This will be called when the target is in user mode
74 * This function will only be called when we use
75 * "PERF_SAMPLE_CALLCHAIN" in
76 * kernel/events/core.c:perf_prepare_sample()
78 * How to trigger perf_callchain_[user/kernel] :
79 * $ perf record -e cpu-clock --call-graph fp ./program
80 * $ perf report --call-graph
82 * On C-SKY platform, the program being sampled and the C library
83 * need to be compiled with * -mbacktrace, otherwise the user
84 * stack will not contain function frame.
86 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
89 struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
92 /* C-SKY does not support virtualization. */
93 if (guest_cbs && guest_cbs->is_in_guest())
97 perf_callchain_store(entry, regs->pc);
100 * While backtrace from leaf function, lr is normally
101 * not saved inside frame on C-SKY, so get lr from pt_regs
102 * at the sample point. However, lr value can be incorrect if
103 * lr is used as temp register
105 fp = user_backtrace(entry, fp, regs->lr);
107 while (fp && !(fp & 0x3) && entry->nr < entry->max_stack)
108 fp = user_backtrace(entry, fp, 0);
111 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
112 struct pt_regs *regs)
114 struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
115 struct stackframe fr;
117 /* C-SKY does not support virtualization. */
118 if (guest_cbs && guest_cbs->is_in_guest()) {
119 pr_warn("C-SKY does not support perf in guest mode!");
123 fr.fp = regs->regs[4];
125 walk_stackframe(&fr, entry);