[mirror_ubuntu-artful-kernel.git] / arch / powerpc / kernel / perf_callchain.c

/*
 * 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


/*
 * 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;
}

void
perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
{
	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];
	perf_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;
			perf_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;
		}

		perf_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;

	pagefault_disable();
	if (!__get_user_inatomic(*ret, ptr)) {
		pagefault_enable();
		return 0;
	}
	pagefault_enable();

	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;

	pagefault_disable();
	if (!__get_user_inatomic(*ret, ptr)) {
		pagefault_enable();
		return 0;
	}
	pagefault_enable();

	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 perf_callchain_entry *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 = regs->nip;
	lr = regs->link;
	sp = regs->gpr[1];
	perf_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;
			perf_callchain_store(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;
	}
}

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)
{
	int rc;

	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
	    ((unsigned long)ptr & 3))
		return -EFAULT;

	pagefault_disable();
	rc = __get_user_inatomic(*ret, ptr);
	pagefault_enable();

	return rc;
}

static inline void perf_callchain_user_64(struct perf_callchain_entry *entry,
					  struct pt_regs *regs)
{
}

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, &regs))
		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, &regs))
		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 perf_callchain_entry *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 = regs->nip;
	lr = regs->link;
	sp = regs->gpr[1];
	perf_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;
			perf_callchain_store(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;
	}
}

void
perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
{
	if (current_is_64bit())
		perf_callchain_user_64(entry, regs);
	else
		perf_callchain_user_32(entry, regs);
}
Commit	Line	Data
20002ded PM	1	/*
	2	* Performance counter callchain support - powerpc architecture code
	3	*
	4	* Copyright © 2009 Paul Mackerras, IBM Corporation.
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11	#include <linux/kernel.h>
	12	#include <linux/sched.h>
cdd6c482	13	#include <linux/perf_event.h>
20002ded PM	14	#include <linux/percpu.h>
	15	#include <linux/uaccess.h>
	16	#include <linux/mm.h>
	17	#include <asm/ptrace.h>
	18	#include <asm/pgtable.h>
	19	#include <asm/sigcontext.h>
	20	#include <asm/ucontext.h>
	21	#include <asm/vdso.h>
	22	#ifdef CONFIG_PPC64
	23	#include "ppc32.h"
	24	#endif
	25
20002ded PM	26
	27	/*
	28	* Is sp valid as the address of the next kernel stack frame after prev_sp?
	29	* The next frame may be in a different stack area but should not go
	30	* back down in the same stack area.
	31	*/
	32	static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
	33	{
	34	if (sp & 0xf)
	35	return 0; /* must be 16-byte aligned */
	36	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
	37	return 0;
	38	if (sp >= prev_sp + STACK_FRAME_OVERHEAD)
	39	return 1;
	40	/*
	41	* sp could decrease when we jump off an interrupt stack
	42	* back to the regular process stack.
	43	*/
	44	if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
	45	return 1;
	46	return 0;
	47	}
	48
56962b44 FW	49	void
56962b44 FW	50	perf_callchain_kernel(struct perf_callchain_entry entry, struct pt_regs regs)
20002ded PM	51	{
	52	unsigned long sp, next_sp;
	53	unsigned long next_ip;
	54	unsigned long lr;
	55	long level = 0;
	56	unsigned long *fp;
	57
	58	lr = regs->link;
	59	sp = regs->gpr[1];
70791ce9	60	perf_callchain_store(entry, regs->nip);
20002ded PM	61
	62	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
	63	return;
	64
	65	for (;;) {
	66	fp = (unsigned long *) sp;
	67	next_sp = fp[0];
	68
	69	if (next_sp == sp + STACK_INT_FRAME_SIZE &&
	70	fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
	71	/*
	72	* This looks like an interrupt frame for an
	73	* interrupt that occurred in the kernel
	74	*/
	75	regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
	76	next_ip = regs->nip;
	77	lr = regs->link;
	78	level = 0;
70791ce9	79	perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
20002ded PM	80
	81	} else {
	82	if (level == 0)
	83	next_ip = lr;
	84	else
	85	next_ip = fp[STACK_FRAME_LR_SAVE];
	86
	87	/*
	88	* We can't tell which of the first two addresses
	89	* we get are valid, but we can filter out the
	90	* obviously bogus ones here. We replace them
	91	* with 0 rather than removing them entirely so
	92	* that userspace can tell which is which.
	93	*/
	94	if ((level == 1 && next_ip == lr) \|\|
	95	(level <= 1 && !kernel_text_address(next_ip)))
	96	next_ip = 0;
	97
	98	++level;
	99	}
	100
70791ce9	101	perf_callchain_store(entry, next_ip);
20002ded PM	102	if (!valid_next_sp(next_sp, sp))
	103	return;
	104	sp = next_sp;
	105	}
	106	}
	107
	108	#ifdef CONFIG_PPC64
20002ded PM	109	/*
	110	* On 64-bit we don't want to invoke hash_page on user addresses from
	111	* interrupt context, so if the access faults, we read the page tables
	112	* to find which page (if any) is mapped and access it directly.
	113	*/
	114	static int read_user_stack_slow(void __user ptr, void ret, int nb)
	115	{
	116	pgd_t *pgdir;
	117	pte_t *ptep, pte;
a4fe3ce7	118	unsigned shift;
20002ded PM	119	unsigned long addr = (unsigned long) ptr;
	120	unsigned long offset;
	121	unsigned long pfn;
	122	void *kaddr;
	123
	124	pgdir = current->mm->pgd;
	125	if (!pgdir)
	126	return -EFAULT;
	127
a4fe3ce7 DG	128	ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift);
	129	if (!shift)
	130	shift = PAGE_SHIFT;
20002ded PM	131
20002ded PM	132	/* align address to page boundary */
a4fe3ce7	133	offset = addr & ((1UL << shift) - 1);
20002ded PM	134	addr -= offset;
20002ded PM	135
20002ded PM	136	if (ptep == NULL)
	137	return -EFAULT;
	138	pte = *ptep;
	139	if (!pte_present(pte) \|\| !(pte_val(pte) & _PAGE_USER))
	140	return -EFAULT;
	141	pfn = pte_pfn(pte);
	142	if (!page_is_ram(pfn))
	143	return -EFAULT;
	144
	145	/* no highmem to worry about here */
	146	kaddr = pfn_to_kaddr(pfn);
	147	memcpy(ret, kaddr + offset, nb);
	148	return 0;
	149	}
	150
	151	static int read_user_stack_64(unsigned long __user ptr, unsigned long ret)
	152	{
	153	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) \|\|
	154	((unsigned long)ptr & 7))
	155	return -EFAULT;
	156
b59a1bfc DA	157	pagefault_disable();
	158	if (!__get_user_inatomic(*ret, ptr)) {
	159	pagefault_enable();
20002ded	160	return 0;
b59a1bfc DA	161	}
b59a1bfc DA	162	pagefault_enable();
20002ded PM	163
	164	return read_user_stack_slow(ptr, ret, 8);
	165	}
	166
	167	static int read_user_stack_32(unsigned int __user ptr, unsigned int ret)
	168	{
	169	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) \|\|
	170	((unsigned long)ptr & 3))
	171	return -EFAULT;
	172
b59a1bfc DA	173	pagefault_disable();
	174	if (!__get_user_inatomic(*ret, ptr)) {
	175	pagefault_enable();
20002ded	176	return 0;
b59a1bfc DA	177	}
b59a1bfc DA	178	pagefault_enable();
20002ded PM	179
	180	return read_user_stack_slow(ptr, ret, 4);
	181	}
	182
	183	static inline int valid_user_sp(unsigned long sp, int is_64)
	184	{
	185	if (!sp \|\| (sp & 7) \|\| sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
	186	return 0;
	187	return 1;
	188	}
	189
	190	/*
	191	* 64-bit user processes use the same stack frame for RT and non-RT signals.
	192	*/
	193	struct signal_frame_64 {
	194	char dummy[__SIGNAL_FRAMESIZE];
	195	struct ucontext uc;
	196	unsigned long unused[2];
	197	unsigned int tramp[6];
	198	struct siginfo *pinfo;
	199	void *puc;
	200	struct siginfo info;
	201	char abigap[288];
	202	};
	203
	204	static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
	205	{
	206	if (nip == fp + offsetof(struct signal_frame_64, tramp))
	207	return 1;
	208	if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
	209	nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
	210	return 1;
	211	return 0;
	212	}
	213
	214	/*
	215	* Do some sanity checking on the signal frame pointed to by sp.
	216	* We check the pinfo and puc pointers in the frame.
	217	*/
	218	static int sane_signal_64_frame(unsigned long sp)
	219	{
	220	struct signal_frame_64 __user *sf;
	221	unsigned long pinfo, puc;
	222
	223	sf = (struct signal_frame_64 __user *) sp;
	224	if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) \|\|
	225	read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
	226	return 0;
	227	return pinfo == (unsigned long) &sf->info &&
	228	puc == (unsigned long) &sf->uc;
	229	}
	230
56962b44 FW	231	static void perf_callchain_user_64(struct perf_callchain_entry *entry,
56962b44 FW	232	struct pt_regs *regs)
20002ded PM	233	{
	234	unsigned long sp, next_sp;
	235	unsigned long next_ip;
	236	unsigned long lr;
	237	long level = 0;
	238	struct signal_frame_64 __user *sigframe;
	239	unsigned long __user fp, uregs;
	240
	241	next_ip = regs->nip;
	242	lr = regs->link;
	243	sp = regs->gpr[1];
70791ce9	244	perf_callchain_store(entry, next_ip);
20002ded PM	245
	246	for (;;) {
	247	fp = (unsigned long __user *) sp;
	248	if (!valid_user_sp(sp, 1) \|\| read_user_stack_64(fp, &next_sp))
	249	return;
	250	if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
	251	return;
	252
	253	/*
	254	* Note: the next_sp - sp >= signal frame size check
	255	* is true when next_sp < sp, which can happen when
	256	* transitioning from an alternate signal stack to the
	257	* normal stack.
	258	*/
	259	if (next_sp - sp >= sizeof(struct signal_frame_64) &&
	260	(is_sigreturn_64_address(next_ip, sp) \|\|
	261	(level <= 1 && is_sigreturn_64_address(lr, sp))) &&
	262	sane_signal_64_frame(sp)) {
	263	/*
	264	* This looks like an signal frame
	265	*/
	266	sigframe = (struct signal_frame_64 __user *) sp;
	267	uregs = sigframe->uc.uc_mcontext.gp_regs;
	268	if (read_user_stack_64(&uregs[PT_NIP], &next_ip) \|\|
	269	read_user_stack_64(&uregs[PT_LNK], &lr) \|\|
	270	read_user_stack_64(&uregs[PT_R1], &sp))
	271	return;
	272	level = 0;
70791ce9 FW	273	perf_callchain_store(entry, PERF_CONTEXT_USER);
70791ce9 FW	274	perf_callchain_store(entry, next_ip);
20002ded PM	275	continue;
	276	}
	277
	278	if (level == 0)
	279	next_ip = lr;
70791ce9	280	perf_callchain_store(entry, next_ip);
20002ded PM	281	++level;
	282	sp = next_sp;
	283	}
	284	}
	285
	286	static inline int current_is_64bit(void)
	287	{
	288	/*
	289	* We can't use test_thread_flag() here because we may be on an
	290	* interrupt stack, and the thread flags don't get copied over
	291	* from the thread_info on the main stack to the interrupt stack.
	292	*/
	293	return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
	294	}
	295
	296	#else /* CONFIG_PPC64 */
	297	/*
	298	* On 32-bit we just access the address and let hash_page create a
	299	* HPTE if necessary, so there is no need to fall back to reading
	300	* the page tables. Since this is called at interrupt level,
	301	* do_page_fault() won't treat a DSI as a page fault.
	302	*/
	303	static int read_user_stack_32(unsigned int __user ptr, unsigned int ret)
	304	{
b59a1bfc DA	305	int rc;
b59a1bfc DA	306
20002ded PM	307	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) \|\|
	308	((unsigned long)ptr & 3))
	309	return -EFAULT;
	310
b59a1bfc DA	311	pagefault_disable();
	312	rc = __get_user_inatomic(*ret, ptr);
	313	pagefault_enable();
	314
	315	return rc;
20002ded PM	316	}
20002ded PM	317
56962b44 FW	318	static inline void perf_callchain_user_64(struct perf_callchain_entry *entry,
56962b44 FW	319	struct pt_regs *regs)
20002ded PM	320	{
	321	}
	322
	323	static inline int current_is_64bit(void)
	324	{
	325	return 0;
	326	}
	327
	328	static inline int valid_user_sp(unsigned long sp, int is_64)
	329	{
	330	if (!sp \|\| (sp & 7) \|\| sp > TASK_SIZE - 32)
	331	return 0;
	332	return 1;
	333	}
	334
	335	#define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
	336	#define sigcontext32 sigcontext
	337	#define mcontext32 mcontext
	338	#define ucontext32 ucontext
	339	#define compat_siginfo_t struct siginfo
	340
	341	#endif /* CONFIG_PPC64 */
	342
	343	/*
	344	* Layout for non-RT signal frames
	345	*/
	346	struct signal_frame_32 {
	347	char dummy[__SIGNAL_FRAMESIZE32];
	348	struct sigcontext32 sctx;
	349	struct mcontext32 mctx;
	350	int abigap[56];
	351	};
	352
	353	/*
	354	* Layout for RT signal frames
	355	*/
	356	struct rt_signal_frame_32 {
	357	char dummy[__SIGNAL_FRAMESIZE32 + 16];
	358	compat_siginfo_t info;
	359	struct ucontext32 uc;
	360	int abigap[56];
	361	};
	362
	363	static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
	364	{
	365	if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
	366	return 1;
	367	if (vdso32_sigtramp && current->mm->context.vdso_base &&
	368	nip == current->mm->context.vdso_base + vdso32_sigtramp)
	369	return 1;
	370	return 0;
	371	}
	372
	373	static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
	374	{
	375	if (nip == fp + offsetof(struct rt_signal_frame_32,
	376	uc.uc_mcontext.mc_pad))
	377	return 1;
	378	if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
	379	nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
	380	return 1;
	381	return 0;
	382	}
	383
384	static int sane_signal_32_frame(unsigned int sp)
385	{
386	struct signal_frame_32 __user *sf;
387	unsigned int regs;
388
389	sf = (struct signal_frame_32 __user *) (unsigned long) sp;
390	if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, &regs))
391	return 0;
392	return regs == (unsigned long) &sf->mctx;
393	}
394
395	static int sane_rt_signal_32_frame(unsigned int sp)
396	{
397	struct rt_signal_frame_32 __user *sf;
398	unsigned int regs;
399
400	sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
401	if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, &regs))
402	return 0;
403	return regs == (unsigned long) &sf->uc.uc_mcontext;
404	}
405
406	static unsigned int __user *signal_frame_32_regs(unsigned int sp,
407	unsigned int next_sp, unsigned int next_ip)
408	{
409	struct mcontext32 __user *mctx = NULL;
410	struct signal_frame_32 __user *sf;
411	struct rt_signal_frame_32 __user *rt_sf;
412
413	/*
414	* Note: the next_sp - sp >= signal frame size check
415	* is true when next_sp < sp, for example, when
416	* transitioning from an alternate signal stack to the
417	* normal stack.
418	*/
419	if (next_sp - sp >= sizeof(struct signal_frame_32) &&
420	is_sigreturn_32_address(next_ip, sp) &&
421	sane_signal_32_frame(sp)) {
422	sf = (struct signal_frame_32 __user *) (unsigned long) sp;
423	mctx = &sf->mctx;
424	}
425
426	if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
427	is_rt_sigreturn_32_address(next_ip, sp) &&
428	sane_rt_signal_32_frame(sp)) {
429	rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
430	mctx = &rt_sf->uc.uc_mcontext;
431	}
432
433	if (!mctx)
434	return NULL;
435	return mctx->mc_gregs;
436	}
437
56962b44 FW	438	static void perf_callchain_user_32(struct perf_callchain_entry *entry,
56962b44 FW	439	struct pt_regs *regs)
20002ded PM	440	{
	441	unsigned int sp, next_sp;
	442	unsigned int next_ip;
	443	unsigned int lr;
	444	long level = 0;
	445	unsigned int __user fp, uregs;
	446
	447	next_ip = regs->nip;
	448	lr = regs->link;
	449	sp = regs->gpr[1];
70791ce9	450	perf_callchain_store(entry, next_ip);
20002ded PM	451
	452	while (entry->nr < PERF_MAX_STACK_DEPTH) {
	453	fp = (unsigned int __user *) (unsigned long) sp;
	454	if (!valid_user_sp(sp, 0) \|\| read_user_stack_32(fp, &next_sp))
	455	return;
	456	if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
	457	return;
	458
	459	uregs = signal_frame_32_regs(sp, next_sp, next_ip);
	460	if (!uregs && level <= 1)
	461	uregs = signal_frame_32_regs(sp, next_sp, lr);
	462	if (uregs) {
	463	/*
	464	* This looks like an signal frame, so restart
	465	* the stack trace with the values in it.
	466	*/
	467	if (read_user_stack_32(&uregs[PT_NIP], &next_ip) \|\|
	468	read_user_stack_32(&uregs[PT_LNK], &lr) \|\|
	469	read_user_stack_32(&uregs[PT_R1], &sp))
	470	return;
	471	level = 0;
70791ce9 FW	472	perf_callchain_store(entry, PERF_CONTEXT_USER);
70791ce9 FW	473	perf_callchain_store(entry, next_ip);
20002ded PM	474	continue;
	475	}
	476
	477	if (level == 0)
	478	next_ip = lr;
70791ce9	479	perf_callchain_store(entry, next_ip);
20002ded PM	480	++level;
	481	sp = next_sp;
	482	}
	483	}
	484
56962b44 FW	485	void
56962b44 FW	486	perf_callchain_user(struct perf_callchain_entry entry, struct pt_regs regs)
20002ded	487	{
56962b44 FW	488	if (current_is_64bit())
	489	perf_callchain_user_64(entry, regs);
	490	else
	491	perf_callchain_user_32(entry, regs);
20002ded	492	}