Re: [PATCH v2 2/2] powerpc: use probe_user_read()

[Christophe Leroy]

Le 08/01/2019 à 10:04, David Hildenbrand a écrit :

On 08.01.19 08:37, Christophe Leroy wrote:

Instead of opencoding, use probe_user_read() to failessly
read a user location.

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
  v2: Using probe_user_read() instead of probe_user_address()

  arch/powerpc/kernel/process.c   | 12 +-----------
  arch/powerpc/mm/fault.c         |  6 +-----
  arch/powerpc/perf/callchain.c   | 20 +++-----------------
  arch/powerpc/perf/core-book3s.c |  8 +-------
  arch/powerpc/sysdev/fsl_pci.c   | 10 ++++------
  5 files changed, 10 insertions(+), 46 deletions(-)

[snip]

diff --git a/arch/powerpc/sysdev/fsl_pci.c b/arch/powerpc/sysdev/fsl_pci.c
index 918be816b097..c8a1b26489f5 100644
--- a/arch/powerpc/sysdev/fsl_pci.c
+++ b/arch/powerpc/sysdev/fsl_pci.c
@@ -1068,13 +1068,11 @@ int fsl_pci_mcheck_exception(struct pt_regs *regs)
        addr += mfspr(SPRN_MCAR);

if (is_in_pci_mem_space(addr)) {

-               if (user_mode(regs)) {
-                       pagefault_disable();
-                       ret = get_user(inst, (__u32 __user *)regs->nip);
-                       pagefault_enable();
-               } else {
+               if (user_mode(regs))
+                       ret = probe_user_read(&inst, (void __user *)regs->nip,
+                                             sizeof(inst));

What about also adding probe_user_address ?

Michael doesn't like it, see https://patchwork.ozlabs.org/patch/1007117/

Christophe

+               else
                        ret = probe_kernel_address((void *)regs->nip, inst);
-               }

if (!ret && mcheck_handle_load(regs, inst)) {

                        regs->nip += 4;