diff options
Diffstat (limited to 'arch/powerpc/perf')
| -rw-r--r-- | arch/powerpc/perf/callchain_64.c | 46 |
1 files changed, 14 insertions, 32 deletions
diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c index df1ffd8b20f2..b63086b663ef 100644 --- a/arch/powerpc/perf/callchain_64.c +++ b/arch/powerpc/perf/callchain_64.c @@ -26,43 +26,25 @@ */ int read_user_stack_slow(void __user *ptr, void *buf, int nb) { - int ret = -EFAULT; - pgd_t *pgdir; - pte_t *ptep, pte; - unsigned int shift; + unsigned long addr = (unsigned long) ptr; unsigned long offset; - unsigned long pfn, flags; + struct page *page; + int nrpages; void *kaddr; - pgdir = current->mm->pgd; - if (!pgdir) - return -EFAULT; + nrpages = __get_user_pages_fast(addr, 1, 1, &page); + if (nrpages == 1) { + kaddr = page_address(page); + + /* align address to page boundary */ + offset = addr & ~PAGE_MASK; - 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; + memcpy(buf, kaddr + offset, nb); + put_page(page); + return 0; + } + return -EFAULT; } static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret) |