File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
new file mode 100644
index 0000000..4e02ae5
--- /dev/null
+++ b/arch/arm/kernel/perf_callchain.c
@@ -0,0 +1,136 @@
+/*
+ * 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 *entry)
+{
+ struct frame_tail buftail;
+ unsigned long err;
+
+ if (!access_ok(VERIFY_READ, 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 *entry, struct pt_regs *regs)
+{
+ struct frame_tail __user *tail;
+
+ if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+ /* We don't support guest os callchain now */
+ return;
+ }
+
+ perf_callchain_store(entry, regs->ARM_pc);
+
+ if (!current->mm)
+ return;
+
+ tail = (struct frame_tail __user *)regs->ARM_fp - 1;
+
+ while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
+ 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 int
+callchain_trace(struct stackframe *fr,
+ void *data)
+{
+ struct perf_callchain_entry *entry = data;
+ perf_callchain_store(entry, fr->pc);
+ return 0;
+}
+
+void
+perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
+{
+ struct stackframe fr;
+
+ if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+ /* We don't support guest os callchain now */
+ return;
+ }
+
+ arm_get_current_stackframe(regs, &fr);
+ walk_stackframe(&fr, callchain_trace, entry);
+}
+
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+ if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+ return perf_guest_cbs->get_guest_ip();
+
+ return instruction_pointer(regs);
+}
+
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+ int misc = 0;
+
+ if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+ if (perf_guest_cbs->is_user_mode())
+ misc |= PERF_RECORD_MISC_GUEST_USER;
+ else
+ misc |= PERF_RECORD_MISC_GUEST_KERNEL;
+ } else {
+ if (user_mode(regs))
+ misc |= PERF_RECORD_MISC_USER;
+ else
+ misc |= PERF_RECORD_MISC_KERNEL;
+ }
+
+ return misc;
+}