linux-kernel - [PATCH v2] powerpc/powermac: Fix low_sleep

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Message-Id: <21b05f7298c1b18f73e6e5b4cd5005aafa24b6da.1599820109.git.christophe.leroy@csgroup.eu>
Date:   Fri, 11 Sep 2020 10:29:15 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2] 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 <christophe.leroy@...roup.eu>
Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@...r.kernel.org
---
v2: Added missing _GLOBAL() to load_segment_registers in head_32.S
---
 arch/powerpc/kernel/head_32.S           | 2 +-
 arch/powerpc/platforms/powermac/sleep.S | 9 +--------
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 5624db0e09a1..0f60743474a2 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -1002,7 +1002,7 @@ 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 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