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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Performance counter callchain support - powerpc architecture code
*
* Copyright © 2009 Paul Mackerras, IBM Corporation.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/perf_event.h>
#include <linux/percpu.h>
#include <linux/uaccess.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <asm/vdso.h>
#include <asm/pte-walk.h>
#include "callchain.h"
/*
* On 64-bit we don't want to invoke hash_page on user addresses from
* interrupt context, so if the access faults, we read the page tables
* to find which page (if any) is mapped and access it directly.
*/
int read_user_stack_slow(const void __user *ptr, void *buf, int nb)
{
unsigned long addr = (unsigned long) ptr;
unsigned long offset;
struct page *page;
void *kaddr;
if (get_user_page_fast_only(addr, FOLL_WRITE, &page)) {
kaddr = page_address(page);
/* align address to page boundary */
offset = addr & ~PAGE_MASK;
memcpy(buf, kaddr + offset, nb);
put_page(page);
return 0;
}
return -EFAULT;
}
static int read_user_stack_64(const unsigned long __user *ptr, unsigned long *ret)
{
return __read_user_stack(ptr, ret, sizeof(*ret));
}
/*
* 64-bit user processes use the same stack frame for RT and non-RT signals.
*/
struct signal_frame_64 {
char dummy[__SIGNAL_FRAMESIZE];
struct ucontext uc;
unsigned long unused[2];
unsigned int tramp[6];
struct siginfo *pinfo;
void *puc;
struct siginfo info;
char abigap[288];
};
static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
{
if (nip == fp + offsetof(struct signal_frame_64, tramp))
return 1;
if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
return 1;
return 0;
}
/*
* Do some sanity checking on the signal frame pointed to by sp.
* We check the pinfo and puc pointers in the frame.
*/
static int sane_signal_64_frame(unsigned long sp)
{
struct signal_frame_64 __user *sf;
unsigned long pinfo, puc;
sf = (struct signal_frame_64 __user *) sp;
if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
return 0;
return pinfo == (unsigned long) &sf->info &&
puc == (unsigned long) &sf->uc;
}
void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
struct pt_regs *regs)
{
unsigned long sp, next_sp;
unsigned long next_ip;
unsigned long lr;
long level = 0;
struct signal_frame_64 __user *sigframe;
unsigned long __user *fp, *uregs;
next_ip = perf_instruction_pointer(regs);
lr = regs->link;
sp = regs->gpr[1];
perf_callchain_store(entry, next_ip);
while (entry->nr < entry->max_stack) {
fp = (unsigned long __user *) sp;
if (invalid_user_sp(sp) || read_user_stack_64(fp, &next_sp))
return;
if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
return;
/*
* Note: the next_sp - sp >= signal frame size check
* is true when next_sp < sp, which can happen when
* transitioning from an alternate signal stack to the
* normal stack.
*/
if (next_sp - sp >= sizeof(struct signal_frame_64) &&
(is_sigreturn_64_address(next_ip, sp) ||
(level <= 1 && is_sigreturn_64_address(lr, sp))) &&
sane_signal_64_frame(sp)) {
/*
* This looks like an signal frame
*/
sigframe = (struct signal_frame_64 __user *) sp;
uregs = sigframe->uc.uc_mcontext.gp_regs;
if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
read_user_stack_64(&uregs[PT_LNK], &lr) ||
read_user_stack_64(&uregs[PT_R1], &sp))
return;
level = 0;
perf_callchain_store_context(entry, PERF_CONTEXT_USER);
perf_callchain_store(entry, next_ip);
continue;
}
if (level == 0)
next_ip = lr;
perf_callchain_store(entry, next_ip);
++level;
sp = next_sp;
}
}
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