[mirror_ubuntu-focal-kernel.git] / arch / powerpc / perf / callchain.c

// 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>
#ifdef CONFIG_PPC64
#include "../kernel/ppc32.h"
#endif
#include <asm/pte-walk.h>


/*
 * 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_MIN_SIZE)
		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_ctx *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, perf_instruction_pointer(regs));

	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_context(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 *buf, int nb)
{
	int ret = -EFAULT;
	pgd_t *pgdir;
	pte_t *ptep, pte;
	unsigned shift;
	unsigned long addr = (unsigned long) ptr;
	unsigned long offset;
	unsigned long pfn, flags;
	void *kaddr;

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

	local_irq_save(flags);
	ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
	if (!ptep)
		goto err_out;
	if (!shift)
		shift = PAGE_SHIFT;

	/* align address to page boundary */
	offset = addr & ((1UL << shift) - 1);

	pte = READ_ONCE(*ptep);
	if (!pte_present(pte) || !pte_user(pte))
		goto err_out;
	pfn = pte_pfn(pte);
	if (!page_is_ram(pfn))
		goto err_out;

	/* no highmem to worry about here */
	kaddr = pfn_to_kaddr(pfn);
	memcpy(buf, kaddr + offset, nb);
	ret = 0;
err_out:
	local_irq_restore(flags);
	return ret;
}

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_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 (!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_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;
	}
}

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_ctx *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_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 (!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_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;
	}
}

void
perf_callchain_user(struct perf_callchain_entry_ctx *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
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
20002ded PM	2	/*
	3	* Performance counter callchain support - powerpc architecture code
	4	*
	5	* Copyright © 2009 Paul Mackerras, IBM Corporation.
20002ded PM	6	*/
	7	#include <linux/kernel.h>
	8	#include <linux/sched.h>
cdd6c482	9	#include <linux/perf_event.h>
20002ded PM	10	#include <linux/percpu.h>
	11	#include <linux/uaccess.h>
	12	#include <linux/mm.h>
	13	#include <asm/ptrace.h>
	14	#include <asm/pgtable.h>
	15	#include <asm/sigcontext.h>
	16	#include <asm/ucontext.h>
	17	#include <asm/vdso.h>
	18	#ifdef CONFIG_PPC64
f2699491	19	#include "../kernel/ppc32.h"
20002ded	20	#endif
94171b19	21	#include <asm/pte-walk.h>
20002ded	22
20002ded PM	23
	24	/*
	25	* Is sp valid as the address of the next kernel stack frame after prev_sp?
	26	* The next frame may be in a different stack area but should not go
	27	* back down in the same stack area.
	28	*/
	29	static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
	30	{
	31	if (sp & 0xf)
	32	return 0; /* must be 16-byte aligned */
	33	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
	34	return 0;
85101af1	35	if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
20002ded PM	36	return 1;
	37	/*
	38	* sp could decrease when we jump off an interrupt stack
	39	* back to the regular process stack.
	40	*/
	41	if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
	42	return 1;
	43	return 0;
	44	}
	45
56962b44	46	void
cfbcf468	47	perf_callchain_kernel(struct perf_callchain_entry_ctx entry, struct pt_regs regs)
20002ded PM	48	{
	49	unsigned long sp, next_sp;
	50	unsigned long next_ip;
	51	unsigned long lr;
	52	long level = 0;
	53	unsigned long *fp;
	54
	55	lr = regs->link;
	56	sp = regs->gpr[1];
6da70948	57	perf_callchain_store(entry, perf_instruction_pointer(regs));
20002ded PM	58
	59	if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
	60	return;
	61
	62	for (;;) {
	63	fp = (unsigned long *) sp;
	64	next_sp = fp[0];
	65
	66	if (next_sp == sp + STACK_INT_FRAME_SIZE &&
	67	fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
	68	/*
	69	* This looks like an interrupt frame for an
	70	* interrupt that occurred in the kernel
	71	*/
	72	regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
	73	next_ip = regs->nip;
	74	lr = regs->link;
	75	level = 0;
3e4de4ec	76	perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);
20002ded PM	77
	78	} else {
	79	if (level == 0)
	80	next_ip = lr;
	81	else
	82	next_ip = fp[STACK_FRAME_LR_SAVE];
	83
	84	/*
	85	* We can't tell which of the first two addresses
	86	* we get are valid, but we can filter out the
	87	* obviously bogus ones here. We replace them
	88	* with 0 rather than removing them entirely so
	89	* that userspace can tell which is which.
	90	*/
	91	if ((level == 1 && next_ip == lr) \|\|
	92	(level <= 1 && !kernel_text_address(next_ip)))
	93	next_ip = 0;
	94
	95	++level;
	96	}
	97
70791ce9	98	perf_callchain_store(entry, next_ip);
20002ded PM	99	if (!valid_next_sp(next_sp, sp))
	100	return;
	101	sp = next_sp;
	102	}
	103	}
	104
	105	#ifdef CONFIG_PPC64
20002ded PM	106	/*
	107	* On 64-bit we don't want to invoke hash_page on user addresses from
	108	* interrupt context, so if the access faults, we read the page tables
	109	* to find which page (if any) is mapped and access it directly.
	110	*/
691e95fd	111	static int read_user_stack_slow(void __user ptr, void buf, int nb)
20002ded	112	{
691e95fd	113	int ret = -EFAULT;
20002ded PM	114	pgd_t *pgdir;
20002ded PM	115	pte_t *ptep, pte;
a4fe3ce7	116	unsigned shift;
20002ded PM	117	unsigned long addr = (unsigned long) ptr;
20002ded PM	118	unsigned long offset;
691e95fd	119	unsigned long pfn, flags;
20002ded PM	120	void *kaddr;
	121
	122	pgdir = current->mm->pgd;
	123	if (!pgdir)
	124	return -EFAULT;
	125
691e95fd	126	local_irq_save(flags);
94171b19	127	ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
691e95fd AK	128	if (!ptep)
691e95fd AK	129	goto err_out;
a4fe3ce7 DG	130	if (!shift)
a4fe3ce7 DG	131	shift = PAGE_SHIFT;
20002ded PM	132
20002ded PM	133	/* align address to page boundary */
a4fe3ce7	134	offset = addr & ((1UL << shift) - 1);
20002ded	135
691e95fd	136	pte = READ_ONCE(*ptep);
e7bfc462	137	if (!pte_present(pte) \|\| !pte_user(pte))
691e95fd	138	goto err_out;
20002ded PM	139	pfn = pte_pfn(pte);
20002ded PM	140	if (!page_is_ram(pfn))
691e95fd	141	goto err_out;
20002ded PM	142
	143	/* no highmem to worry about here */
	144	kaddr = pfn_to_kaddr(pfn);
691e95fd AK	145	memcpy(buf, kaddr + offset, nb);
	146	ret = 0;
	147	err_out:
	148	local_irq_restore(flags);
	149	return ret;
20002ded PM	150	}
	151
	152	static int read_user_stack_64(unsigned long __user ptr, unsigned long ret)
	153	{
	154	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) \|\|
	155	((unsigned long)ptr & 7))
	156	return -EFAULT;
	157
b59a1bfc DA	158	pagefault_disable();
	159	if (!__get_user_inatomic(*ret, ptr)) {
	160	pagefault_enable();
20002ded	161	return 0;
b59a1bfc DA	162	}
b59a1bfc DA	163	pagefault_enable();
20002ded PM	164
	165	return read_user_stack_slow(ptr, ret, 8);
	166	}
	167
	168	static int read_user_stack_32(unsigned int __user ptr, unsigned int ret)
	169	{
	170	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) \|\|
	171	((unsigned long)ptr & 3))
	172	return -EFAULT;
	173
b59a1bfc DA	174	pagefault_disable();
	175	if (!__get_user_inatomic(*ret, ptr)) {
	176	pagefault_enable();
20002ded	177	return 0;
b59a1bfc DA	178	}
b59a1bfc DA	179	pagefault_enable();
20002ded PM	180
	181	return read_user_stack_slow(ptr, ret, 4);
	182	}
	183
	184	static inline int valid_user_sp(unsigned long sp, int is_64)
	185	{
	186	if (!sp \|\| (sp & 7) \|\| sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
	187	return 0;
	188	return 1;
	189	}
	190
	191	/*
	192	* 64-bit user processes use the same stack frame for RT and non-RT signals.
	193	*/
	194	struct signal_frame_64 {
	195	char dummy[__SIGNAL_FRAMESIZE];
	196	struct ucontext uc;
	197	unsigned long unused[2];
	198	unsigned int tramp[6];
	199	struct siginfo *pinfo;
	200	void *puc;
	201	struct siginfo info;
	202	char abigap[288];
	203	};
	204
	205	static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
	206	{
	207	if (nip == fp + offsetof(struct signal_frame_64, tramp))
	208	return 1;
	209	if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
	210	nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
	211	return 1;
	212	return 0;
	213	}
	214
	215	/*
	216	* Do some sanity checking on the signal frame pointed to by sp.
	217	* We check the pinfo and puc pointers in the frame.
	218	*/
	219	static int sane_signal_64_frame(unsigned long sp)
	220	{
	221	struct signal_frame_64 __user *sf;
	222	unsigned long pinfo, puc;
	223
	224	sf = (struct signal_frame_64 __user *) sp;
	225	if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) \|\|
	226	read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
	227	return 0;
	228	return pinfo == (unsigned long) &sf->info &&
	229	puc == (unsigned long) &sf->uc;
	230	}
	231
cfbcf468	232	static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
56962b44	233	struct pt_regs *regs)
20002ded PM	234	{
	235	unsigned long sp, next_sp;
	236	unsigned long next_ip;
	237	unsigned long lr;
	238	long level = 0;
	239	struct signal_frame_64 __user *sigframe;
	240	unsigned long __user fp, uregs;
	241
6da70948	242	next_ip = perf_instruction_pointer(regs);
20002ded PM	243	lr = regs->link;
20002ded PM	244	sp = regs->gpr[1];
70791ce9	245	perf_callchain_store(entry, next_ip);
20002ded	246
3b1fff08	247	while (entry->nr < entry->max_stack) {
20002ded PM	248	fp = (unsigned long __user *) sp;
	249	if (!valid_user_sp(sp, 1) \|\| read_user_stack_64(fp, &next_sp))
	250	return;
	251	if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
	252	return;
	253
	254	/*
	255	* Note: the next_sp - sp >= signal frame size check
	256	* is true when next_sp < sp, which can happen when
	257	* transitioning from an alternate signal stack to the
	258	* normal stack.
	259	*/
	260	if (next_sp - sp >= sizeof(struct signal_frame_64) &&
	261	(is_sigreturn_64_address(next_ip, sp) \|\|
	262	(level <= 1 && is_sigreturn_64_address(lr, sp))) &&
	263	sane_signal_64_frame(sp)) {
	264	/*
	265	* This looks like an signal frame
	266	*/
	267	sigframe = (struct signal_frame_64 __user *) sp;
	268	uregs = sigframe->uc.uc_mcontext.gp_regs;
	269	if (read_user_stack_64(&uregs[PT_NIP], &next_ip) \|\|
	270	read_user_stack_64(&uregs[PT_LNK], &lr) \|\|
	271	read_user_stack_64(&uregs[PT_R1], &sp))
	272	return;
	273	level = 0;
3e4de4ec	274	perf_callchain_store_context(entry, PERF_CONTEXT_USER);
70791ce9	275	perf_callchain_store(entry, next_ip);
20002ded PM	276	continue;
	277	}
	278
	279	if (level == 0)
	280	next_ip = lr;
70791ce9	281	perf_callchain_store(entry, next_ip);
20002ded PM	282	++level;
	283	sp = next_sp;
	284	}
	285	}
	286
	287	static inline int current_is_64bit(void)
	288	{
	289	/*
	290	* We can't use test_thread_flag() here because we may be on an
	291	* interrupt stack, and the thread flags don't get copied over
	292	* from the thread_info on the main stack to the interrupt stack.
	293	*/
	294	return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
	295	}
	296
	297	#else /* CONFIG_PPC64 */
	298	/*
	299	* On 32-bit we just access the address and let hash_page create a
	300	* HPTE if necessary, so there is no need to fall back to reading
	301	* the page tables. Since this is called at interrupt level,
	302	* do_page_fault() won't treat a DSI as a page fault.
	303	*/
	304	static int read_user_stack_32(unsigned int __user ptr, unsigned int ret)
	305	{
b59a1bfc DA	306	int rc;
b59a1bfc DA	307
20002ded PM	308	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) \|\|
	309	((unsigned long)ptr & 3))
	310	return -EFAULT;
	311
b59a1bfc DA	312	pagefault_disable();
	313	rc = __get_user_inatomic(*ret, ptr);
	314	pagefault_enable();
	315
	316	return rc;
20002ded PM	317	}
20002ded PM	318
cfbcf468	319	static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
56962b44	320	struct pt_regs *regs)
20002ded PM	321	{
	322	}
	323
	324	static inline int current_is_64bit(void)
	325	{
	326	return 0;
	327	}
	328
	329	static inline int valid_user_sp(unsigned long sp, int is_64)
	330	{
	331	if (!sp \|\| (sp & 7) \|\| sp > TASK_SIZE - 32)
	332	return 0;
	333	return 1;
	334	}
	335
	336	#define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
	337	#define sigcontext32 sigcontext
	338	#define mcontext32 mcontext
	339	#define ucontext32 ucontext
	340	#define compat_siginfo_t struct siginfo
	341
	342	#endif /* CONFIG_PPC64 */
	343
	344	/*
	345	* Layout for non-RT signal frames
	346	*/
	347	struct signal_frame_32 {
	348	char dummy[__SIGNAL_FRAMESIZE32];
	349	struct sigcontext32 sctx;
	350	struct mcontext32 mctx;
	351	int abigap[56];
	352	};
	353
	354	/*
	355	* Layout for RT signal frames
	356	*/
	357	struct rt_signal_frame_32 {
	358	char dummy[__SIGNAL_FRAMESIZE32 + 16];
	359	compat_siginfo_t info;
	360	struct ucontext32 uc;
	361	int abigap[56];
	362	};
	363
	364	static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
	365	{
	366	if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
	367	return 1;
	368	if (vdso32_sigtramp && current->mm->context.vdso_base &&
	369	nip == current->mm->context.vdso_base + vdso32_sigtramp)
	370	return 1;
	371	return 0;
	372	}
	373
	374	static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
	375	{
	376	if (nip == fp + offsetof(struct rt_signal_frame_32,
	377	uc.uc_mcontext.mc_pad))
	378	return 1;
	379	if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
	380	nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
	381	return 1;
	382	return 0;
	383	}
	384
385	static int sane_signal_32_frame(unsigned int sp)
386	{
387	struct signal_frame_32 __user *sf;
388	unsigned int regs;
389
390	sf = (struct signal_frame_32 __user *) (unsigned long) sp;
391	if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, &regs))
392	return 0;
393	return regs == (unsigned long) &sf->mctx;
394	}
395
396	static int sane_rt_signal_32_frame(unsigned int sp)
397	{
398	struct rt_signal_frame_32 __user *sf;
399	unsigned int regs;
400
401	sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
402	if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, &regs))
403	return 0;
404	return regs == (unsigned long) &sf->uc.uc_mcontext;
405	}
406
407	static unsigned int __user *signal_frame_32_regs(unsigned int sp,
408	unsigned int next_sp, unsigned int next_ip)
409	{
410	struct mcontext32 __user *mctx = NULL;
411	struct signal_frame_32 __user *sf;
412	struct rt_signal_frame_32 __user *rt_sf;
413
414	/*
415	* Note: the next_sp - sp >= signal frame size check
416	* is true when next_sp < sp, for example, when
417	* transitioning from an alternate signal stack to the
418	* normal stack.
419	*/
420	if (next_sp - sp >= sizeof(struct signal_frame_32) &&
421	is_sigreturn_32_address(next_ip, sp) &&
422	sane_signal_32_frame(sp)) {
423	sf = (struct signal_frame_32 __user *) (unsigned long) sp;
424	mctx = &sf->mctx;
425	}
426
427	if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
428	is_rt_sigreturn_32_address(next_ip, sp) &&
429	sane_rt_signal_32_frame(sp)) {
430	rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
431	mctx = &rt_sf->uc.uc_mcontext;
432	}
433
434	if (!mctx)
435	return NULL;
436	return mctx->mc_gregs;
437	}
438
cfbcf468	439	static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
56962b44	440	struct pt_regs *regs)
20002ded PM	441	{
	442	unsigned int sp, next_sp;
	443	unsigned int next_ip;
	444	unsigned int lr;
	445	long level = 0;
	446	unsigned int __user fp, uregs;
	447
6da70948	448	next_ip = perf_instruction_pointer(regs);
20002ded PM	449	lr = regs->link;
20002ded PM	450	sp = regs->gpr[1];
70791ce9	451	perf_callchain_store(entry, next_ip);
20002ded	452
3b1fff08	453	while (entry->nr < entry->max_stack) {
20002ded PM	454	fp = (unsigned int __user *) (unsigned long) sp;
	455	if (!valid_user_sp(sp, 0) \|\| read_user_stack_32(fp, &next_sp))
	456	return;
	457	if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
	458	return;
	459
	460	uregs = signal_frame_32_regs(sp, next_sp, next_ip);
	461	if (!uregs && level <= 1)
	462	uregs = signal_frame_32_regs(sp, next_sp, lr);
	463	if (uregs) {
	464	/*
	465	* This looks like an signal frame, so restart
	466	* the stack trace with the values in it.
	467	*/
	468	if (read_user_stack_32(&uregs[PT_NIP], &next_ip) \|\|
	469	read_user_stack_32(&uregs[PT_LNK], &lr) \|\|
	470	read_user_stack_32(&uregs[PT_R1], &sp))
	471	return;
	472	level = 0;
3e4de4ec	473	perf_callchain_store_context(entry, PERF_CONTEXT_USER);
70791ce9	474	perf_callchain_store(entry, next_ip);
20002ded PM	475	continue;
	476	}
	477
	478	if (level == 0)
	479	next_ip = lr;
70791ce9	480	perf_callchain_store(entry, next_ip);
20002ded PM	481	++level;
	482	sp = next_sp;
	483	}
	484	}
	485
56962b44	486	void
cfbcf468	487	perf_callchain_user(struct perf_callchain_entry_ctx entry, struct pt_regs regs)
20002ded	488	{
56962b44 FW	489	if (current_is_64bit())
	490	perf_callchain_user_64(entry, regs);
	491	else
	492	perf_callchain_user_32(entry, regs);
20002ded	493	}