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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/pgtable.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <asm/vdso.h>
#include <asm/pte-walk.h>
#include "callchain.h"
#ifdef CONFIG_PPC64
#include "../kernel/ppc32.h"
#else /* CONFIG_PPC64 */
#define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
#define sigcontext32 sigcontext
#define mcontext32 mcontext
#define ucontext32 ucontext
#define compat_siginfo_t struct siginfo
#endif /* 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)
{
int rc;
if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
((unsigned long)ptr & 3))
return -EFAULT;
rc = probe_user_read(ret, ptr, sizeof(*ret));
if (IS_ENABLED(CONFIG_PPC64) && rc)
return read_user_stack_slow(ptr, ret, 4);
return rc;
}
/*
* 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;
}
void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
struct pt_regs *regs)
{
unsigned int sp, next_sp;
unsigned int next_ip;
unsigned int lr;
long level = 0;
unsigned int __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 int __user *) (unsigned long) sp;
if (invalid_user_sp(sp) || 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;
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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