[deliverable/linux.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

/*
 * 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

#ifdef CONFIG_HUGETLB_PAGE
#define is_huge_psize(pagesize)	(HPAGE_SHIFT && mmu_huge_psizes[pagesize])
#else
#define is_huge_psize(pagesize)	0
#endif

/*
 * 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;
	int pagesize;
	unsigned long addr = (unsigned long) ptr;
	unsigned long offset;
	unsigned long pfn;
	void *kaddr;

	pgdir = current->mm->pgd;
	if (!pgdir)
		return -EFAULT;

	pagesize = get_slice_psize(current->mm, addr);

	/* align address to page boundary */
	offset = addr & ((1ul << mmu_psize_defs[pagesize].shift) - 1);
	addr -= offset;

	if (is_huge_psize(pagesize))
		ptep = huge_pte_offset(current->mm, addr);
	else
		ptep = find_linux_pte(pgdir, addr);

	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, &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 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, callchain);

struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
{
	struct perf_callchain_entry *entry = &__get_cpu_var(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;
}
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
	26	/*
	27	* Store another value in a callchain_entry.
	28	*/
	29	static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip)
	30	{
	31	unsigned int nr = entry->nr;
	32
	33	if (nr < PERF_MAX_STACK_DEPTH) {
	34	entry->ip[nr] = ip;
	35	entry->nr = nr + 1;
	36	}
	37	}
	38
	39	/*
	40	* Is sp valid as the address of the next kernel stack frame after prev_sp?
	41	* The next frame may be in a different stack area but should not go
	42	* back down in the same stack area.
	43	*/
	44	static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
	45	{
	46	if (sp & 0xf)
	47	return 0; /* must be 16-byte aligned */
	48	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
	49	return 0;
	50	if (sp >= prev_sp + STACK_FRAME_OVERHEAD)
	51	return 1;
	52	/*
	53	* sp could decrease when we jump off an interrupt stack
	54	* back to the regular process stack.
	55	*/
	56	if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
	57	return 1;
	58	return 0;
	59	}
	60
	61	static void perf_callchain_kernel(struct pt_regs *regs,
	62	struct perf_callchain_entry *entry)
	63	{
	64	unsigned long sp, next_sp;
	65	unsigned long next_ip;
	66	unsigned long lr;
	67	long level = 0;
	68	unsigned long *fp;
	69
	70	lr = regs->link;
	71	sp = regs->gpr[1];
	72	callchain_store(entry, PERF_CONTEXT_KERNEL);
	73	callchain_store(entry, regs->nip);
	74
	75	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
	76	return;
	77
78	for (;;) {
79	fp = (unsigned long *) sp;
80	next_sp = fp[0];
81
82	if (next_sp == sp + STACK_INT_FRAME_SIZE &&
83	fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
84	/*
85	* This looks like an interrupt frame for an
86	* interrupt that occurred in the kernel
87	*/
88	regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
89	next_ip = regs->nip;
90	lr = regs->link;
91	level = 0;
92	callchain_store(entry, PERF_CONTEXT_KERNEL);
93
94	} else {
95	if (level == 0)
96	next_ip = lr;
97	else
98	next_ip = fp[STACK_FRAME_LR_SAVE];
99
100	/*
101	* We can't tell which of the first two addresses
102	* we get are valid, but we can filter out the
103	* obviously bogus ones here. We replace them
104	* with 0 rather than removing them entirely so
105	* that userspace can tell which is which.
106	*/
107	if ((level == 1 && next_ip == lr) \|\|
108	(level <= 1 && !kernel_text_address(next_ip)))
109	next_ip = 0;
110
111	++level;
112	}
113
114	callchain_store(entry, next_ip);
115	if (!valid_next_sp(next_sp, sp))
116	return;
117	sp = next_sp;
118	}
119	}
120
121	#ifdef CONFIG_PPC64
122
123	#ifdef CONFIG_HUGETLB_PAGE
124	#define is_huge_psize(pagesize) (HPAGE_SHIFT && mmu_huge_psizes[pagesize])
125	#else
126	#define is_huge_psize(pagesize) 0
127	#endif
128
129	/*
130	* On 64-bit we don't want to invoke hash_page on user addresses from
131	* interrupt context, so if the access faults, we read the page tables
132	* to find which page (if any) is mapped and access it directly.
133	*/
134	static int read_user_stack_slow(void __user ptr, void ret, int nb)
135	{
136	pgd_t *pgdir;
137	pte_t *ptep, pte;
138	int pagesize;
139	unsigned long addr = (unsigned long) ptr;
140	unsigned long offset;
141	unsigned long pfn;
142	void *kaddr;
143
144	pgdir = current->mm->pgd;
145	if (!pgdir)
146	return -EFAULT;
147
148	pagesize = get_slice_psize(current->mm, addr);
149
150	/* align address to page boundary */
151	offset = addr & ((1ul << mmu_psize_defs[pagesize].shift) - 1);
152	addr -= offset;
153
154	if (is_huge_psize(pagesize))
155	ptep = huge_pte_offset(current->mm, addr);
156	else
157	ptep = find_linux_pte(pgdir, addr);
158
159	if (ptep == NULL)
160	return -EFAULT;
161	pte = *ptep;
162	if (!pte_present(pte) \|\| !(pte_val(pte) & _PAGE_USER))
163	return -EFAULT;
164	pfn = pte_pfn(pte);
165	if (!page_is_ram(pfn))
166	return -EFAULT;
167
168	/* no highmem to worry about here */
169	kaddr = pfn_to_kaddr(pfn);
170	memcpy(ret, kaddr + offset, nb);
171	return 0;
172	}
173
174	static int read_user_stack_64(unsigned long __user ptr, unsigned long ret)
175	{
176	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) \|\|
177	((unsigned long)ptr & 7))
178	return -EFAULT;
179
180	if (!__get_user_inatomic(*ret, ptr))
181	return 0;
182
183	return read_user_stack_slow(ptr, ret, 8);
184	}
185
186	static int read_user_stack_32(unsigned int __user ptr, unsigned int ret)
187	{
188	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) \|\|
189	((unsigned long)ptr & 3))
190	return -EFAULT;
191
192	if (!__get_user_inatomic(*ret, ptr))
193	return 0;
194
195	return read_user_stack_slow(ptr, ret, 4);
196	}
197
198	static inline int valid_user_sp(unsigned long sp, int is_64)
199	{
200	if (!sp \|\| (sp & 7) \|\| sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
201	return 0;
202	return 1;
203	}
204
205	/*
206	* 64-bit user processes use the same stack frame for RT and non-RT signals.
207	*/
208	struct signal_frame_64 {
209	char dummy[__SIGNAL_FRAMESIZE];
210	struct ucontext uc;
211	unsigned long unused[2];
212	unsigned int tramp[6];
213	struct siginfo *pinfo;
214	void *puc;
215	struct siginfo info;
216	char abigap[288];
217	};
218
219	static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
220	{
221	if (nip == fp + offsetof(struct signal_frame_64, tramp))
222	return 1;
223	if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
224	nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
225	return 1;
226	return 0;
227	}
228
229	/*
230	* Do some sanity checking on the signal frame pointed to by sp.
231	* We check the pinfo and puc pointers in the frame.
232	*/
233	static int sane_signal_64_frame(unsigned long sp)
234	{
235	struct signal_frame_64 __user *sf;
236	unsigned long pinfo, puc;
237
238	sf = (struct signal_frame_64 __user *) sp;
239	if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) \|\|
240	read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
241	return 0;
242	return pinfo == (unsigned long) &sf->info &&
243	puc == (unsigned long) &sf->uc;
244	}
245
246	static void perf_callchain_user_64(struct pt_regs *regs,
247	struct perf_callchain_entry *entry)
248	{
249	unsigned long sp, next_sp;
250	unsigned long next_ip;
251	unsigned long lr;
252	long level = 0;
253	struct signal_frame_64 __user *sigframe;
254	unsigned long __user fp, uregs;
255
256	next_ip = regs->nip;
257	lr = regs->link;
258	sp = regs->gpr[1];
259	callchain_store(entry, PERF_CONTEXT_USER);
260	callchain_store(entry, next_ip);
261
262	for (;;) {
263	fp = (unsigned long __user *) sp;
264	if (!valid_user_sp(sp, 1) \|\| read_user_stack_64(fp, &next_sp))
265	return;
266	if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
267	return;
268
269	/*
270	* Note: the next_sp - sp >= signal frame size check
271	* is true when next_sp < sp, which can happen when
272	* transitioning from an alternate signal stack to the
273	* normal stack.
274	*/
275	if (next_sp - sp >= sizeof(struct signal_frame_64) &&
276	(is_sigreturn_64_address(next_ip, sp) \|\|
277	(level <= 1 && is_sigreturn_64_address(lr, sp))) &&
278	sane_signal_64_frame(sp)) {
279	/*
280	* This looks like an signal frame
281	*/
282	sigframe = (struct signal_frame_64 __user *) sp;
283	uregs = sigframe->uc.uc_mcontext.gp_regs;
284	if (read_user_stack_64(&uregs[PT_NIP], &next_ip) \|\|
285	read_user_stack_64(&uregs[PT_LNK], &lr) \|\|
286	read_user_stack_64(&uregs[PT_R1], &sp))
287	return;
288	level = 0;
289	callchain_store(entry, PERF_CONTEXT_USER);
290	callchain_store(entry, next_ip);
291	continue;
292	}
293
294	if (level == 0)
295	next_ip = lr;
296	callchain_store(entry, next_ip);
297	++level;
298	sp = next_sp;
299	}
300	}
301
302	static inline int current_is_64bit(void)
303	{
304	/*
305	* We can't use test_thread_flag() here because we may be on an
306	* interrupt stack, and the thread flags don't get copied over
307	* from the thread_info on the main stack to the interrupt stack.
308	*/
309	return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
310	}
311
312	#else /* CONFIG_PPC64 */
313	/*
314	* On 32-bit we just access the address and let hash_page create a
315	* HPTE if necessary, so there is no need to fall back to reading
316	* the page tables. Since this is called at interrupt level,
317	* do_page_fault() won't treat a DSI as a page fault.
318	*/
319	static int read_user_stack_32(unsigned int __user ptr, unsigned int ret)
320	{
321	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) \|\|
322	((unsigned long)ptr & 3))
323	return -EFAULT;
324
325	return __get_user_inatomic(*ret, ptr);
326	}
327
328	static inline void perf_callchain_user_64(struct pt_regs *regs,
329	struct perf_callchain_entry *entry)
330	{
331	}
332
333	static inline int current_is_64bit(void)
334	{
335	return 0;
336	}
337
338	static inline int valid_user_sp(unsigned long sp, int is_64)
339	{
340	if (!sp \|\| (sp & 7) \|\| sp > TASK_SIZE - 32)
341	return 0;
342	return 1;
343	}
344
345	#define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
346	#define sigcontext32 sigcontext
347	#define mcontext32 mcontext
348	#define ucontext32 ucontext
349	#define compat_siginfo_t struct siginfo
350
351	#endif /* CONFIG_PPC64 */
352
353	/*
354	* Layout for non-RT signal frames
355	*/
356	struct signal_frame_32 {
357	char dummy[__SIGNAL_FRAMESIZE32];
358	struct sigcontext32 sctx;
359	struct mcontext32 mctx;
360	int abigap[56];
361	};
362
363	/*
364	* Layout for RT signal frames
365	*/
366	struct rt_signal_frame_32 {
367	char dummy[__SIGNAL_FRAMESIZE32 + 16];
368	compat_siginfo_t info;
369	struct ucontext32 uc;
370	int abigap[56];
371	};
372
373	static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
374	{
375	if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
376	return 1;
377	if (vdso32_sigtramp && current->mm->context.vdso_base &&
378	nip == current->mm->context.vdso_base + vdso32_sigtramp)
379	return 1;
380	return 0;
381	}
382
383	static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
384	{
385	if (nip == fp + offsetof(struct rt_signal_frame_32,
386	uc.uc_mcontext.mc_pad))
387	return 1;
388	if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
389	nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
390	return 1;
391	return 0;
392	}
393
394	static int sane_signal_32_frame(unsigned int sp)
395	{
396	struct signal_frame_32 __user *sf;
397	unsigned int regs;
398
399	sf = (struct signal_frame_32 __user *) (unsigned long) sp;
400	if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, &regs))
401	return 0;
402	return regs == (unsigned long) &sf->mctx;
403	}
404
405	static int sane_rt_signal_32_frame(unsigned int sp)
406	{
407	struct rt_signal_frame_32 __user *sf;
408	unsigned int regs;
409
410	sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
411	if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, &regs))
412	return 0;
413	return regs == (unsigned long) &sf->uc.uc_mcontext;
414	}
415
416	static unsigned int __user *signal_frame_32_regs(unsigned int sp,
417	unsigned int next_sp, unsigned int next_ip)
418	{
419	struct mcontext32 __user *mctx = NULL;
420	struct signal_frame_32 __user *sf;
421	struct rt_signal_frame_32 __user *rt_sf;
422
423	/*
424	* Note: the next_sp - sp >= signal frame size check
425	* is true when next_sp < sp, for example, when
426	* transitioning from an alternate signal stack to the
427	* normal stack.
428	*/
429	if (next_sp - sp >= sizeof(struct signal_frame_32) &&
430	is_sigreturn_32_address(next_ip, sp) &&
431	sane_signal_32_frame(sp)) {
432	sf = (struct signal_frame_32 __user *) (unsigned long) sp;
433	mctx = &sf->mctx;
434	}
435
436	if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
437	is_rt_sigreturn_32_address(next_ip, sp) &&
438	sane_rt_signal_32_frame(sp)) {
439	rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
440	mctx = &rt_sf->uc.uc_mcontext;
441	}
442
443	if (!mctx)
444	return NULL;
445	return mctx->mc_gregs;
446	}
447
448	static void perf_callchain_user_32(struct pt_regs *regs,
449	struct perf_callchain_entry *entry)
450	{
451	unsigned int sp, next_sp;
452	unsigned int next_ip;
453	unsigned int lr;
454	long level = 0;
455	unsigned int __user fp, uregs;
456
457	next_ip = regs->nip;
458	lr = regs->link;
459	sp = regs->gpr[1];
460	callchain_store(entry, PERF_CONTEXT_USER);
461	callchain_store(entry, next_ip);
462
463	while (entry->nr < PERF_MAX_STACK_DEPTH) {
464	fp = (unsigned int __user *) (unsigned long) sp;
465	if (!valid_user_sp(sp, 0) \|\| read_user_stack_32(fp, &next_sp))
466	return;
467	if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
468	return;
469
470	uregs = signal_frame_32_regs(sp, next_sp, next_ip);
471	if (!uregs && level <= 1)
472	uregs = signal_frame_32_regs(sp, next_sp, lr);
473	if (uregs) {
474	/*
475	* This looks like an signal frame, so restart
476	* the stack trace with the values in it.
477	*/
478	if (read_user_stack_32(&uregs[PT_NIP], &next_ip) \|\|
479	read_user_stack_32(&uregs[PT_LNK], &lr) \|\|
480	read_user_stack_32(&uregs[PT_R1], &sp))
481	return;
482	level = 0;
483	callchain_store(entry, PERF_CONTEXT_USER);
484	callchain_store(entry, next_ip);
485	continue;
486	}
487
488	if (level == 0)
489	next_ip = lr;
490	callchain_store(entry, next_ip);
491	++level;
492	sp = next_sp;
493	}
494	}
495
496	/*
497	* Since we can't get PMU interrupts inside a PMU interrupt handler,
498	* we don't need separate irq and nmi entries here.
499	*/
500	static DEFINE_PER_CPU(struct perf_callchain_entry, callchain);
501
502	struct perf_callchain_entry perf_callchain(struct pt_regs regs)
503	{
504	struct perf_callchain_entry *entry = &__get_cpu_var(callchain);
505
506	entry->nr = 0;
507
508	if (current->pid == 0) /* idle task? */
509	return entry;
510
511	if (!user_mode(regs)) {
512	perf_callchain_kernel(regs, entry);
513	if (current->mm)
514	regs = task_pt_regs(current);
515	else
516	regs = NULL;
517	}
518
519	if (regs) {
520	if (current_is_64bit())
521	perf_callchain_user_64(regs, entry);
522	else
523	perf_callchain_user_32(regs, entry);
524	}
525
526	return entry;
527	}