diff options
Diffstat (limited to 'arch/powerpc/perf/callchain.c')
| -rw-r--r-- | arch/powerpc/perf/callchain.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c index ead55351b254..ff09cde20cd2 100644 --- a/arch/powerpc/perf/callchain.c +++ b/arch/powerpc/perf/callchain.c @@ -111,41 +111,45 @@ perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs) * 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) +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; + unsigned long pfn, flags; void *kaddr; pgdir = current->mm->pgd; if (!pgdir) return -EFAULT; + local_irq_save(flags); ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift); + if (!ptep) + goto err_out; if (!shift) shift = PAGE_SHIFT; /* align address to page boundary */ offset = addr & ((1UL << shift) - 1); - addr -= offset; - if (ptep == NULL) - return -EFAULT; - pte = *ptep; + pte = READ_ONCE(*ptep); if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER)) - return -EFAULT; + goto err_out; pfn = pte_pfn(pte); if (!page_is_ram(pfn)) - return -EFAULT; + goto err_out; /* no highmem to worry about here */ kaddr = pfn_to_kaddr(pfn); - memcpy(ret, kaddr + offset, nb); - return 0; + 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) |