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124 lines
3.1 KiB
124 lines
3.1 KiB
// SPDX-License-Identifier: GPL-2.0 |
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// Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. |
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#include <linux/perf_event.h> |
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#include <linux/uaccess.h> |
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/* Kernel callchain */ |
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struct stackframe { |
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unsigned long fp; |
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unsigned long lr; |
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}; |
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static int unwind_frame_kernel(struct stackframe *frame) |
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{ |
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unsigned long low = (unsigned long)task_stack_page(current); |
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unsigned long high = low + THREAD_SIZE; |
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if (unlikely(frame->fp < low || frame->fp > high)) |
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return -EPERM; |
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if (kstack_end((void *)frame->fp) || frame->fp & 0x3) |
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return -EPERM; |
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*frame = *(struct stackframe *)frame->fp; |
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if (__kernel_text_address(frame->lr)) { |
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int graph = 0; |
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frame->lr = ftrace_graph_ret_addr(NULL, &graph, frame->lr, |
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NULL); |
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} |
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return 0; |
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} |
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static void notrace walk_stackframe(struct stackframe *fr, |
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struct perf_callchain_entry_ctx *entry) |
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{ |
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do { |
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perf_callchain_store(entry, fr->lr); |
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} while (unwind_frame_kernel(fr) >= 0); |
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} |
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/* |
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* Get the return address for a single stackframe and return a pointer to the |
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* next frame tail. |
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*/ |
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static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, |
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unsigned long fp, unsigned long reg_lr) |
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{ |
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struct stackframe buftail; |
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unsigned long lr = 0; |
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unsigned long *user_frame_tail = (unsigned long *)fp; |
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/* Check accessibility of one struct frame_tail beyond */ |
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if (!access_ok(user_frame_tail, sizeof(buftail))) |
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return 0; |
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if (__copy_from_user_inatomic(&buftail, user_frame_tail, |
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sizeof(buftail))) |
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return 0; |
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if (reg_lr != 0) |
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lr = reg_lr; |
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else |
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lr = buftail.lr; |
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fp = buftail.fp; |
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perf_callchain_store(entry, lr); |
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return fp; |
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} |
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/* |
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* This will be called when the target is in user mode |
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* This function will only be called when we use |
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* "PERF_SAMPLE_CALLCHAIN" in |
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* kernel/events/core.c:perf_prepare_sample() |
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* |
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* How to trigger perf_callchain_[user/kernel] : |
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* $ perf record -e cpu-clock --call-graph fp ./program |
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* $ perf report --call-graph |
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* |
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* On C-SKY platform, the program being sampled and the C library |
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* need to be compiled with * -mbacktrace, otherwise the user |
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* stack will not contain function frame. |
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*/ |
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void perf_callchain_user(struct perf_callchain_entry_ctx *entry, |
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struct pt_regs *regs) |
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{ |
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unsigned long fp = 0; |
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/* C-SKY does not support virtualization. */ |
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) |
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return; |
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fp = regs->regs[4]; |
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perf_callchain_store(entry, regs->pc); |
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/* |
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* While backtrace from leaf function, lr is normally |
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* not saved inside frame on C-SKY, so get lr from pt_regs |
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* at the sample point. However, lr value can be incorrect if |
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* lr is used as temp register |
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*/ |
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fp = user_backtrace(entry, fp, regs->lr); |
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while (fp && !(fp & 0x3) && entry->nr < entry->max_stack) |
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fp = user_backtrace(entry, fp, 0); |
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} |
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void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, |
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struct pt_regs *regs) |
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{ |
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struct stackframe fr; |
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/* C-SKY does not support virtualization. */ |
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { |
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pr_warn("C-SKY does not support perf in guest mode!"); |
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return; |
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} |
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fr.fp = regs->regs[4]; |
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fr.lr = regs->lr; |
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walk_stackframe(&fr, entry); |
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}
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