powerpc/powermac: Fix low_sleep_handler with KUAP and KUEP

low_sleep_handler() has an hardcoded restore of segment registers
that doesn't take KUAP and KUEP into account.

Use head_32's load_segment_registers() routine instead.

Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/21b05f7298c1b18f73e6e5b4cd5005aafa24b6da.1599820109.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index b0e184f..2bd0aa3 100644 (file)
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -996,7 +996,7 @@ BEGIN_MMU_FTR_SECTION
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_HIGH_BATS)
        blr
 
-load_segment_registers:
+_GLOBAL(load_segment_registers)
        li      r0, NUM_USER_SEGMENTS /* load up user segment register values */
        mtctr   r0              /* for context 0 */
        li      r3, 0           /* Kp = 0, Ks = 0, VSID = 0 */

diff --git a/arch/powerpc/platforms/powermac/sleep.S b/arch/powerpc/platforms/powermac/sleep.S
index f9a680f..51bfdfe 100644 (file)
--- a/arch/powerpc/platforms/powermac/sleep.S
+++ b/arch/powerpc/platforms/powermac/sleep.S
@@ -294,14 +294,7 @@ grackle_wake_up:
         * we do any r1 memory access as we are not sure they
         * are in a sane state above the first 256Mb region
         */
-       li      r0,16           /* load up segment register values */
-       mtctr   r0              /* for context 0 */
-       lis     r3,0x2000       /* Ku = 1, VSID = 0 */
-       li      r4,0
-3:     mtsrin  r3,r4
-       addi    r3,r3,0x111     /* increment VSID */
-       addis   r4,r4,0x1000    /* address of next segment */
-       bdnz    3b
+       bl      load_segment_registers
        sync
        isync