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-rw-r--r--arch/arm/kernel/perf_callchain.c116
1 files changed, 116 insertions, 0 deletions
diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
new file mode 100644
index 0000000000..7147edbe56
--- /dev/null
+++ b/arch/arm/kernel/perf_callchain.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM callchain support
+ *
+ * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
+ * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
+ *
+ * This code is based on the ARM OProfile backtrace code.
+ */
+#include <linux/perf_event.h>
+#include <linux/uaccess.h>
+
+#include <asm/stacktrace.h>
+
+/*
+ * The registers we're interested in are at the end of the variable
+ * length saved register structure. The fp points at the end of this
+ * structure so the address of this struct is:
+ * (struct frame_tail *)(xxx->fp)-1
+ *
+ * This code has been adapted from the ARM OProfile support.
+ */
+struct frame_tail {
+ struct frame_tail __user *fp;
+ unsigned long sp;
+ unsigned long lr;
+} __attribute__((packed));
+
+/*
+ * Get the return address for a single stackframe and return a pointer to the
+ * next frame tail.
+ */
+static struct frame_tail __user *
+user_backtrace(struct frame_tail __user *tail,
+ struct perf_callchain_entry_ctx *entry)
+{
+ struct frame_tail buftail;
+ unsigned long err;
+
+ if (!access_ok(tail, sizeof(buftail)))
+ return NULL;
+
+ pagefault_disable();
+ err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
+ pagefault_enable();
+
+ if (err)
+ return NULL;
+
+ perf_callchain_store(entry, buftail.lr);
+
+ /*
+ * Frame pointers should strictly progress back up the stack
+ * (towards higher addresses).
+ */
+ if (tail + 1 >= buftail.fp)
+ return NULL;
+
+ return buftail.fp - 1;
+}
+
+void
+perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
+{
+ struct frame_tail __user *tail;
+
+ perf_callchain_store(entry, regs->ARM_pc);
+
+ if (!current->mm)
+ return;
+
+ tail = (struct frame_tail __user *)regs->ARM_fp - 1;
+
+ while ((entry->nr < entry->max_stack) &&
+ tail && !((unsigned long)tail & 0x3))
+ tail = user_backtrace(tail, entry);
+}
+
+/*
+ * Gets called by walk_stackframe() for every stackframe. This will be called
+ * whist unwinding the stackframe and is like a subroutine return so we use
+ * the PC.
+ */
+static bool
+callchain_trace(void *data, unsigned long pc)
+{
+ struct perf_callchain_entry_ctx *entry = data;
+ perf_callchain_store(entry, pc);
+ return true;
+}
+
+void
+perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
+{
+ struct stackframe fr;
+
+ arm_get_current_stackframe(regs, &fr);
+ walk_stackframe(&fr, callchain_trace, entry);
+}
+
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+ int misc = 0;
+
+ if (user_mode(regs))
+ misc |= PERF_RECORD_MISC_USER;
+ else
+ misc |= PERF_RECORD_MISC_KERNEL;
+
+ return misc;
+}