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-rw-r--r--arch/powerpc/perf/callchain.c24
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)