| // 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) |
| { |
| if (kstack_end((void *)frame->fp)) |
| return -EPERM; |
| if (frame->fp & 0x3 || frame->fp < TASK_SIZE) |
| 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_frame_tail = (unsigned long *)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) |
| { |
| unsigned long fp = 0; |
| |
| /* C-SKY does not support virtualization. */ |
| if (perf_guest_cbs && perf_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 stackframe fr; |
| |
| /* C-SKY does not support virtualization. */ |
| if (perf_guest_cbs && perf_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); |
| } |