/*
* Performance counter callchain support - powerpc architecture code
*
* Copyright © 2009 Paul Mackerras, IBM Corporation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#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/pgtable.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <asm/vdso.h>
#ifdef CONFIG_PPC64
#include "ppc32.h"
#endif
/*
* Store another value in a callchain_entry.
*/
static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip)
{
unsigned int nr = entry->nr;
if (nr < PERF_MAX_STACK_DEPTH) {
entry->ip[nr] = ip;
entry->nr = nr + 1;
}
}
/*
* Is sp valid as the address of the next kernel stack frame after prev_sp?
* The next frame may be in a different stack area but should not go
* back down in the same stack area.
*/
static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
{
if (sp & 0xf)
return 0; /* must be 16-byte aligned */
if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
return 0;
if (sp >= prev_sp + STACK_FRAME_OVERHEAD)
return 1;
/*
* sp could decrease when we jump off an interrupt stack
* back to the regular process stack.
*/
if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
return 1;
return 0;
}
static void perf_callchain_kernel(struct pt_regs *regs,
struct perf_callchain_entry *entry)
{
unsigned long sp, next_sp;
unsigned long next_ip;
unsigned long lr;
long level = 0;
unsigned long *fp;
lr = regs->link;
sp = regs->gpr[1];
callchain_store(entry, PERF_CONTEXT_KERNEL);
callchain_store(entry, regs->nip);
if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
return;
for (;;) {
fp = (unsigned long *) sp;
next_sp = fp[0];
if (next_sp == sp + STACK_INT_FRAME_SIZE &&
fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
/*
* This looks like an interrupt frame for an
* interrupt that occurred in the kernel
*/
regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
next_ip = regs->nip;
lr = regs->link;
level = 0;
callchain_store(entry, PERF_CONTEXT_KERNEL);
} else {
if (level == 0)
next_ip = lr;
else
next_ip = fp[STACK_FRAME_LR_SAVE];
/*
* We can't tell which of the first two addresses
* we get are valid, but we can filter out the
* obviously bogus ones here. We replace them
* with 0 rather than removing them entirely so
* that userspace can tell which is which.
*/
if ((level == 1 && next_ip == lr) ||
(level <= 1 && !kernel_text_address(next_ip)))
next_ip = 0;
++level;
}
callchain_store(entry, next_ip);
if (!valid_next_sp(next_sp, sp))
return;
sp = next_sp;
}
}
#ifdef CONFIG_PPC64
/*
* 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.
*/
static int read_user_stack_slow(void __user *ptr, void *ret, int nb)
{
pgd_t *pgdir;
pte_t *ptep, pte;
unsigned shift;
unsigned long addr = (unsigned long) ptr;
unsigned long offset;
unsigned long pfn;
void *kaddr;
pgdir = current->mm->pgd;
if (!pgdir)
return -EFAULT;
ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift);
if (!shift)
shift = PAGE_SHIFT;
/* align address to page boundary */
offset = addr & ((1UL << shift) - 1);
addr -= offset;
if (ptep == NULL)
return -EFAULT;
pte = *ptep;
if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER))
return -EFAULT;
pfn = pte_pfn(pte);
if (!page_is_ram(pfn))
return -EFAULT;
/* no highmem to worry about here */
kaddr = pfn_to_kaddr(pfn);
memcpy(ret, kaddr + offset, nb);
return 0;
}
static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
{
if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
((unsigned long)ptr & 7))
return -EFAULT;
if (!__get_user_inatomic(*ret, ptr))
return 0;
return read_user_stack_slow(ptr, ret, 8);
}
static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
{
if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
((unsigned long)ptr & 3))
return -EFAULT;
if (!__get_user_inatomic(*ret, ptr))
return 0;
return read_user_stack_slow(ptr, ret, 4);
}
static inline int valid_user_sp(unsigned long sp, int is_64)
{
if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
return 0;
return 1;
}
/*
* 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;
}
static void perf_callchain_user_64(struct pt_regs *regs,
struct perf_callchain_entry *entry)
{
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 = regs->nip;
lr = regs->link;
sp = regs->gpr[1];
callchain_store(entry, PERF_CONTEXT_USER);
callchain_store(entry, next_ip);
for (;;) {
fp = (unsigned long __user *) sp;
if (!valid_user_sp(sp, 1) || 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;
callchain_store(entry, PERF_CONTEXT_USER);
callchain_store(entry, next_ip);
continue;
}
if (level == 0)
next_ip = lr;
callchain_store(entry, next_ip);
++level;
sp = next_sp;
}
}
static inline int current_is_64bit(void)
{
/*
* We can't use test_thread_flag() here because we may be on an
* interrupt stack, and the thread flags don't get copied over
* from the thread_info on the main stack to the interrupt stack.
*/
return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
}
#else /* CONFIG_PPC64 */
/*
* On 32-bit we just access the address and let hash_page create a
* HPTE if necessary, so there is no need to fall back to reading
* the page tables. Since this is called at interrupt level,
* do_page_fault() won't treat a DSI as a page fault.
*/
static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
{
if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
((unsigned long)ptr & 3))
return -EFAULT;
return __get_user_inatomic(*ret, ptr);
}
static inline void perf_callchain_user_64(struct pt_regs *regs,
struct perf_callchain_entry *entry)
{
}
static inline int current_is_64bit(void)
{
return 0;
}
static inline int valid_user_sp(unsigned long sp, int is_64)
{
if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
return 0;
return 1;
}
#define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
#define sigcontext32 sigcontext
#define mcontext32 mcontext
#define ucontext32 ucontext
#define compat_siginfo_t struct siginfo
#endif /* CONFIG_PPC64 */
/*
* Layout for non-RT signal frames
*/
struct signal_frame_32 {
char dummy[__SIGNAL_FRAMESIZE32];
struct sigcontext32 sctx;
struct mcontext32 mctx;
int abigap[56];
};
/*
* Layout for RT signal frames
*/
struct rt_signal_frame_32 {
char dummy[__SIGNAL_FRAMESIZE32 + 16];
compat_siginfo_t info;
struct ucontext32 uc;
int abigap[56];
};
static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
{
if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
return 1;
if (vdso32_sigtramp && current->mm->context.vdso_base &&
nip == current->mm->context.vdso_base + vdso32_sigtramp)
return 1;
return 0;
}
static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
{
if (nip == fp + offsetof(struct rt_signal_frame_32,
uc.uc_mcontext.mc_pad))
return 1;
if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
return 1;
return 0;
}
static int sane_signal_32_frame(unsigned int sp)
{
struct signal_frame_32 __user *sf;
unsigned int regs;
sf = (struct signal_frame_32 __user *) (unsigned long) sp;
if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, ®s))
return 0;
return regs == (unsigned long) &sf->mctx;
}
static int sane_rt_signal_32_frame(unsigned int sp)
{
struct rt_signal_frame_32 __user *sf;
unsigned int regs;
sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, ®s))
return 0;
return regs == (unsigned long) &sf->uc.uc_mcontext;
}
static unsigned int __user *signal_frame_32_regs(unsigned int sp,
unsigned int next_sp, unsigned int next_ip)
{
struct mcontext32 __user *mctx = NULL;
struct signal_frame_32 __user *sf;
struct rt_signal_frame_32 __user *rt_sf;
/*
* Note: the next_sp - sp >= signal frame size check
* is true when next_sp < sp, for example, when
* transitioning from an alternate signal stack to the
* normal stack.
*/
if (next_sp - sp >= sizeof(struct signal_frame_32) &&
is_sigreturn_32_address(next_ip, sp) &&
sane_signal_32_frame(sp)) {
sf = (struct signal_frame_32 __user *) (unsigned long) sp;
mctx = &sf->mctx;
}
if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
is_rt_sigreturn_32_address(next_ip, sp) &&
sane_rt_signal_32_frame(sp)) {
rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
mctx = &rt_sf->uc.uc_mcontext;
}
if (!mctx)
return NULL;
return mctx->mc_gregs;
}
static void perf_callchain_user_32(struct pt_regs *regs,
struct perf_callchain_entry *entry)
{
unsigned int sp, next_sp;
unsigned int next_ip;
unsigned int lr;
long level = 0;
unsigned int __user *fp, *uregs;
next_ip = regs->nip;
lr = regs->link;
sp = regs->gpr[1];
callchain_store(entry, PERF_CONTEXT_USER);
callchain_store(entry, next_ip);
while (entry->nr < PERF_MAX_STACK_DEPTH) {
fp = (unsigned int __user *) (unsigned long) sp;
if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
return;
if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
return;
uregs = signal_frame_32_regs(sp, next_sp, next_ip);
if (!uregs && level <= 1)
uregs = signal_frame_32_regs(sp, next_sp, lr);
if (uregs) {
/*
* This looks like an signal frame, so restart
* the stack trace with the values in it.
*/
if (read_user_stack_32(&uregs[PT_NIP], &next_ip) ||
read_user_stack_32(&uregs[PT_LNK], &lr) ||
read_user_stack_32(&uregs[PT_R1], &sp))
return;
level = 0;
callchain_store(entry, PERF_CONTEXT_USER);
callchain_store(entry, next_ip);
continue;
}
if (level == 0)
next_ip = lr;
callchain_store(entry, next_ip);
++level;
sp = next_sp;
}
}
/*
* Since we can't get PMU interrupts inside a PMU interrupt handler,
* we don't need separate irq and nmi entries here.
*/
static DEFINE_PER_CPU(struct perf_callchain_entry, cpu_perf_callchain);
struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
{
struct perf_callchain_entry *entry = &__get_cpu_var(cpu_perf_callchain);
entry->nr = 0;
if (current->pid == 0) /* idle task? */
return entry;
if (!user_mode(regs)) {
perf_callchain_kernel(regs, entry);
if (current->mm)
regs = task_pt_regs(current);
else
regs = NULL;
}
if (regs) {
if (current_is_64bit())
perf_callchain_user_64(regs, entry);
else
perf_callchain_user_32(regs, entry);
}
return entry;
}
