495 lines
12 KiB
C
495 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Performance counter callchain support - powerpc architecture code
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*
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* Copyright © 2009 Paul Mackerras, IBM Corporation.
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/perf_event.h>
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#include <linux/percpu.h>
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#include <linux/uaccess.h>
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#include <linux/mm.h>
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#include <asm/ptrace.h>
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#include <asm/pgtable.h>
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#include <asm/sigcontext.h>
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#include <asm/ucontext.h>
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#include <asm/vdso.h>
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#ifdef CONFIG_PPC64
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#include "../kernel/ppc32.h"
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#endif
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#include <asm/pte-walk.h>
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/*
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* Is sp valid as the address of the next kernel stack frame after prev_sp?
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* The next frame may be in a different stack area but should not go
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* back down in the same stack area.
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*/
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static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
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{
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if (sp & 0xf)
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return 0; /* must be 16-byte aligned */
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if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
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return 0;
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if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
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return 1;
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/*
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* sp could decrease when we jump off an interrupt stack
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* back to the regular process stack.
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*/
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if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
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return 1;
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return 0;
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}
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void
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perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
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{
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unsigned long sp, next_sp;
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unsigned long next_ip;
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unsigned long lr;
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long level = 0;
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unsigned long *fp;
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lr = regs->link;
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sp = regs->gpr[1];
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perf_callchain_store(entry, perf_instruction_pointer(regs));
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if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
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return;
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for (;;) {
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fp = (unsigned long *) sp;
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next_sp = fp[0];
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if (next_sp == sp + STACK_INT_FRAME_SIZE &&
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validate_sp(sp, current, STACK_INT_FRAME_SIZE) &&
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fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
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/*
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* This looks like an interrupt frame for an
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* interrupt that occurred in the kernel
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*/
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regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
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next_ip = regs->nip;
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lr = regs->link;
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level = 0;
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perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);
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} else {
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if (level == 0)
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next_ip = lr;
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else
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next_ip = fp[STACK_FRAME_LR_SAVE];
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/*
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* We can't tell which of the first two addresses
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* we get are valid, but we can filter out the
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* obviously bogus ones here. We replace them
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* with 0 rather than removing them entirely so
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* that userspace can tell which is which.
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*/
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if ((level == 1 && next_ip == lr) ||
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(level <= 1 && !kernel_text_address(next_ip)))
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next_ip = 0;
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++level;
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}
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perf_callchain_store(entry, next_ip);
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if (!valid_next_sp(next_sp, sp))
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return;
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sp = next_sp;
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}
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}
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#ifdef CONFIG_PPC64
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/*
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* On 64-bit we don't want to invoke hash_page on user addresses from
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* interrupt context, so if the access faults, we read the page tables
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* to find which page (if any) is mapped and access it directly.
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*/
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static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
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{
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int ret = -EFAULT;
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pgd_t *pgdir;
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pte_t *ptep, pte;
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unsigned shift;
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unsigned long addr = (unsigned long) ptr;
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unsigned long offset;
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unsigned long pfn, flags;
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void *kaddr;
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pgdir = current->mm->pgd;
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if (!pgdir)
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return -EFAULT;
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local_irq_save(flags);
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ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
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if (!ptep)
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goto err_out;
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if (!shift)
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shift = PAGE_SHIFT;
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/* align address to page boundary */
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offset = addr & ((1UL << shift) - 1);
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pte = READ_ONCE(*ptep);
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if (!pte_present(pte) || !pte_user(pte))
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goto err_out;
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pfn = pte_pfn(pte);
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if (!page_is_ram(pfn))
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goto err_out;
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/* no highmem to worry about here */
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kaddr = pfn_to_kaddr(pfn);
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memcpy(buf, kaddr + offset, nb);
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ret = 0;
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err_out:
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local_irq_restore(flags);
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return ret;
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}
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static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
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{
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if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
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((unsigned long)ptr & 7))
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return -EFAULT;
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pagefault_disable();
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if (!__get_user_inatomic(*ret, ptr)) {
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pagefault_enable();
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return 0;
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}
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pagefault_enable();
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return read_user_stack_slow(ptr, ret, 8);
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}
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static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
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{
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if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
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((unsigned long)ptr & 3))
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return -EFAULT;
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pagefault_disable();
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if (!__get_user_inatomic(*ret, ptr)) {
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pagefault_enable();
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return 0;
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}
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pagefault_enable();
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return read_user_stack_slow(ptr, ret, 4);
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}
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static inline int valid_user_sp(unsigned long sp, int is_64)
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{
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if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
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return 0;
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return 1;
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}
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/*
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* 64-bit user processes use the same stack frame for RT and non-RT signals.
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*/
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struct signal_frame_64 {
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char dummy[__SIGNAL_FRAMESIZE];
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struct ucontext uc;
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unsigned long unused[2];
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unsigned int tramp[6];
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struct siginfo *pinfo;
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void *puc;
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struct siginfo info;
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char abigap[288];
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};
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static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
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{
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if (nip == fp + offsetof(struct signal_frame_64, tramp))
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return 1;
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if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
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nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
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return 1;
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return 0;
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}
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/*
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* Do some sanity checking on the signal frame pointed to by sp.
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* We check the pinfo and puc pointers in the frame.
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*/
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static int sane_signal_64_frame(unsigned long sp)
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{
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struct signal_frame_64 __user *sf;
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unsigned long pinfo, puc;
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sf = (struct signal_frame_64 __user *) sp;
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if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
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read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
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return 0;
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return pinfo == (unsigned long) &sf->info &&
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puc == (unsigned long) &sf->uc;
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}
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static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
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struct pt_regs *regs)
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{
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unsigned long sp, next_sp;
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unsigned long next_ip;
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unsigned long lr;
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long level = 0;
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struct signal_frame_64 __user *sigframe;
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unsigned long __user *fp, *uregs;
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next_ip = perf_instruction_pointer(regs);
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lr = regs->link;
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sp = regs->gpr[1];
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perf_callchain_store(entry, next_ip);
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while (entry->nr < entry->max_stack) {
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fp = (unsigned long __user *) sp;
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if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
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return;
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if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
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return;
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/*
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* Note: the next_sp - sp >= signal frame size check
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* is true when next_sp < sp, which can happen when
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* transitioning from an alternate signal stack to the
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* normal stack.
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*/
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if (next_sp - sp >= sizeof(struct signal_frame_64) &&
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(is_sigreturn_64_address(next_ip, sp) ||
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(level <= 1 && is_sigreturn_64_address(lr, sp))) &&
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sane_signal_64_frame(sp)) {
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/*
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* This looks like an signal frame
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*/
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sigframe = (struct signal_frame_64 __user *) sp;
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uregs = sigframe->uc.uc_mcontext.gp_regs;
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if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
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read_user_stack_64(&uregs[PT_LNK], &lr) ||
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read_user_stack_64(&uregs[PT_R1], &sp))
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return;
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level = 0;
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perf_callchain_store_context(entry, PERF_CONTEXT_USER);
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perf_callchain_store(entry, next_ip);
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continue;
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}
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if (level == 0)
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next_ip = lr;
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perf_callchain_store(entry, next_ip);
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++level;
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sp = next_sp;
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}
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}
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static inline int current_is_64bit(void)
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{
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/*
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* We can't use test_thread_flag() here because we may be on an
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* interrupt stack, and the thread flags don't get copied over
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* from the thread_info on the main stack to the interrupt stack.
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*/
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return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
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}
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#else /* CONFIG_PPC64 */
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/*
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* On 32-bit we just access the address and let hash_page create a
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* HPTE if necessary, so there is no need to fall back to reading
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* the page tables. Since this is called at interrupt level,
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* do_page_fault() won't treat a DSI as a page fault.
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*/
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static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
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{
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int rc;
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if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
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((unsigned long)ptr & 3))
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return -EFAULT;
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pagefault_disable();
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rc = __get_user_inatomic(*ret, ptr);
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pagefault_enable();
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return rc;
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}
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static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
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struct pt_regs *regs)
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{
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}
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static inline int current_is_64bit(void)
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{
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return 0;
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}
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static inline int valid_user_sp(unsigned long sp, int is_64)
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{
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if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
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return 0;
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return 1;
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}
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#define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
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#define sigcontext32 sigcontext
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#define mcontext32 mcontext
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#define ucontext32 ucontext
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#define compat_siginfo_t struct siginfo
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#endif /* CONFIG_PPC64 */
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/*
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* Layout for non-RT signal frames
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*/
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struct signal_frame_32 {
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char dummy[__SIGNAL_FRAMESIZE32];
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struct sigcontext32 sctx;
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struct mcontext32 mctx;
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int abigap[56];
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};
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/*
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* Layout for RT signal frames
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*/
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struct rt_signal_frame_32 {
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char dummy[__SIGNAL_FRAMESIZE32 + 16];
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compat_siginfo_t info;
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struct ucontext32 uc;
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int abigap[56];
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};
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static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
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{
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if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
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return 1;
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if (vdso32_sigtramp && current->mm->context.vdso_base &&
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nip == current->mm->context.vdso_base + vdso32_sigtramp)
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return 1;
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return 0;
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}
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static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
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{
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if (nip == fp + offsetof(struct rt_signal_frame_32,
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uc.uc_mcontext.mc_pad))
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return 1;
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if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
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nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
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return 1;
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return 0;
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}
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static int sane_signal_32_frame(unsigned int sp)
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{
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struct signal_frame_32 __user *sf;
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unsigned int regs;
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sf = (struct signal_frame_32 __user *) (unsigned long) sp;
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if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, ®s))
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return 0;
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return regs == (unsigned long) &sf->mctx;
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}
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static int sane_rt_signal_32_frame(unsigned int sp)
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{
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struct rt_signal_frame_32 __user *sf;
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unsigned int regs;
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sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
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if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, ®s))
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return 0;
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return regs == (unsigned long) &sf->uc.uc_mcontext;
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}
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static unsigned int __user *signal_frame_32_regs(unsigned int sp,
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unsigned int next_sp, unsigned int next_ip)
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{
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struct mcontext32 __user *mctx = NULL;
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struct signal_frame_32 __user *sf;
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struct rt_signal_frame_32 __user *rt_sf;
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/*
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* Note: the next_sp - sp >= signal frame size check
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* is true when next_sp < sp, for example, when
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* transitioning from an alternate signal stack to the
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* normal stack.
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*/
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if (next_sp - sp >= sizeof(struct signal_frame_32) &&
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is_sigreturn_32_address(next_ip, sp) &&
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sane_signal_32_frame(sp)) {
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sf = (struct signal_frame_32 __user *) (unsigned long) sp;
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mctx = &sf->mctx;
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}
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if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
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is_rt_sigreturn_32_address(next_ip, sp) &&
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sane_rt_signal_32_frame(sp)) {
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rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
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mctx = &rt_sf->uc.uc_mcontext;
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}
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if (!mctx)
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return NULL;
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return mctx->mc_gregs;
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}
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static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
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struct pt_regs *regs)
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{
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unsigned int sp, next_sp;
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unsigned int next_ip;
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unsigned int lr;
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long level = 0;
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unsigned int __user *fp, *uregs;
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next_ip = perf_instruction_pointer(regs);
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lr = regs->link;
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sp = regs->gpr[1];
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perf_callchain_store(entry, next_ip);
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while (entry->nr < entry->max_stack) {
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fp = (unsigned int __user *) (unsigned long) sp;
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if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
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return;
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if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
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return;
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uregs = signal_frame_32_regs(sp, next_sp, next_ip);
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if (!uregs && level <= 1)
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uregs = signal_frame_32_regs(sp, next_sp, lr);
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if (uregs) {
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/*
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* This looks like an signal frame, so restart
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* the stack trace with the values in it.
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*/
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if (read_user_stack_32(&uregs[PT_NIP], &next_ip) ||
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read_user_stack_32(&uregs[PT_LNK], &lr) ||
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read_user_stack_32(&uregs[PT_R1], &sp))
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return;
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level = 0;
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perf_callchain_store_context(entry, PERF_CONTEXT_USER);
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perf_callchain_store(entry, next_ip);
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continue;
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}
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if (level == 0)
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next_ip = lr;
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perf_callchain_store(entry, next_ip);
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++level;
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sp = next_sp;
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}
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}
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void
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perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
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{
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if (current_is_64bit())
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perf_callchain_user_64(entry, regs);
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else
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perf_callchain_user_32(entry, regs);
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}
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