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Diffstat (limited to 'arch/powerpc/perf/callchain.c')
| -rw-r--r-- | arch/powerpc/perf/callchain.c | 497 |
1 files changed, 497 insertions, 0 deletions
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c new file mode 100644 index 000000000..0af051a19 --- /dev/null +++ b/arch/powerpc/perf/callchain.c @@ -0,0 +1,497 @@ +/* + * 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 "../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, ®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 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); +} |