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-rw-r--r--arch/riscv/kernel/perf_callchain.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
new file mode 100644
index 0000000000..3348a61de7
--- /dev/null
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
+
+#include <linux/perf_event.h>
+#include <linux/uaccess.h>
+
+#include <asm/stacktrace.h>
+
+/*
+ * 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_ra)
+{
+ struct stackframe buftail;
+ unsigned long ra = 0;
+ unsigned long __user *user_frame_tail =
+ (unsigned long __user *)(fp - sizeof(struct stackframe));
+
+ /* 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_ra != 0)
+ ra = reg_ra;
+ else
+ ra = buftail.ra;
+
+ fp = buftail.fp;
+ if (ra != 0)
+ perf_callchain_store(entry, ra);
+ else
+ return 0;
+
+ 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 RISC-V platform, the program being sampled and the C library
+ * need to be compiled with -fno-omit-frame-pointer, 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;
+
+ fp = regs->s0;
+ perf_callchain_store(entry, regs->epc);
+
+ fp = user_backtrace(entry, fp, regs->ra);
+ while (fp && !(fp & 0x3) && entry->nr < entry->max_stack)
+ fp = user_backtrace(entry, fp, 0);
+}
+
+static bool fill_callchain(void *entry, unsigned long pc)
+{
+ return perf_callchain_store(entry, pc) == 0;
+}
+
+void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
+ struct pt_regs *regs)
+{
+ walk_stackframe(NULL, regs, fill_callchain, entry);
+}