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/*
* Perf callchain handling code.
*
* Based on the ARM perf implementation.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/perf_event.h>
#include <linux/uaccess.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
static bool is_valid_call(unsigned long calladdr)
{
unsigned int callinsn;
/* Check the possible return address is aligned. */
if (!(calladdr & 0x3)) {
if (!get_user(callinsn, (unsigned int *)calladdr)) {
/* Check for CALLR or SWAP PC,D1RtP. */
if ((callinsn & 0xff000000) == 0xab000000 ||
callinsn == 0xa3200aa0)
return true;
}
}
return false;
}
static struct metag_frame __user *
user_backtrace(struct metag_frame __user *user_frame,
struct perf_callchain_entry *entry)
{
struct metag_frame frame;
unsigned long calladdr;
/* We cannot rely on having frame pointers in user code. */
while (1) {
/* Also check accessibility of one struct frame beyond */
if (!access_ok(VERIFY_READ, user_frame, sizeof(frame)))
return 0;
if (__copy_from_user_inatomic(&frame, user_frame,
sizeof(frame)))
return 0;
--user_frame;
calladdr = frame.lr - 4;
if (is_valid_call(calladdr)) {
perf_callchain_store(entry, calladdr);
return user_frame;
}
}
return 0;
}
void
perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
{
unsigned long sp = regs->ctx.AX[0].U0;
struct metag_frame __user *frame;
frame = (struct metag_frame __user *)sp;
--frame;
while ((entry->nr < PERF_MAX_STACK_DEPTH) && frame)
frame = user_backtrace(frame, 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;
fr.fp = regs->ctx.AX[1].U0;
fr.sp = regs->ctx.AX[0].U0;
fr.lr = regs->ctx.DX[4].U1;
fr.pc = regs->ctx.CurrPC;
walk_stackframe(&fr, callchain_trace, entry);
}
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