[PATCH] 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.

Signed-off-by: Christophe Leroy <redacted>
Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@vger.kernel.org
---
 arch/powerpc/platforms/powermac/sleep.S | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/powermac/sleep.S b/arch/powerpc/platforms/powermac/sleep.S
index f9a680fdd9c4..51bfdfe85058 100644
--- 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
 

-- 
2.25.0

Christophe Leroy [off-list ref] writes:

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.

Signed-off-by: Christophe Leroy <redacted>
Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@vger.kernel.org
---
 arch/powerpc/platforms/powermac/sleep.S | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

Doesn't build? pmac32_defconfig, gcc 9.3.0:

ld: arch/powerpc/platforms/powermac/sleep.o: in function `core99_wake_up':
(.text+0x25c): undefined reference to `load_segment_registers'

Missing _GLOBAL() presumably?

cheers

Le 11/09/2020 à 01:56, Michael Ellerman a écrit :

Christophe Leroy [off-list ref] writes:

quoted

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.

Signed-off-by: Christophe Leroy <redacted>
Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@vger.kernel.org
---
  arch/powerpc/platforms/powermac/sleep.S | 9 +--------
  1 file changed, 1 insertion(+), 8 deletions(-)

Doesn't build? pmac32_defconfig, gcc 9.3.0:

ld: arch/powerpc/platforms/powermac/sleep.o: in function `core99_wake_up':
(.text+0x25c): undefined reference to `load_segment_registers'

Missing _GLOBAL() presumably?

Oops .. :(

v2 sent out.

Thanks
Christophe

Christophe Leroy [off-list ref] writes:

Le 11/09/2020 à 01:56, Michael Ellerman a écrit :

quoted

Christophe Leroy [off-list ref] writes:

quoted

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.

Signed-off-by: Christophe Leroy <redacted>
Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@vger.kernel.org
---
  arch/powerpc/platforms/powermac/sleep.S | 9 +--------
  1 file changed, 1 insertion(+), 8 deletions(-)

Doesn't build? pmac32_defconfig, gcc 9.3.0:

ld: arch/powerpc/platforms/powermac/sleep.o: in function `core99_wake_up':
(.text+0x25c): undefined reference to `load_segment_registers'

Missing _GLOBAL() presumably?

Oops .. :(

v2 sent out.

Thanks.

cheers