linux-kernel - [PATCH 4/4] alpha: align stack for page fault and user unaligned trap handlers

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Message-Id: <20250129094312.27399-5-ink@unseen.parts>
Date: Wed, 29 Jan 2025 10:43:12 +0100
From: Ivan Kokshaysky <ink@...een.parts>
To: Richard Henderson <richard.henderson@...aro.org>,
	Matt Turner <mattst88@...il.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	"Paul E. McKenney" <paulmck@...nel.org>
Cc: "Maciej W. Rozycki" <macro@...am.me.uk>,
	Magnus Lindholm <linmag7@...il.com>,
	linux-alpha@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] alpha: align stack for page fault and user unaligned trap handlers

do_page_fault() and do_entUna() are special because they use
non-standard stack frame layout. Fix them manually.

Tested-by: Magnus Lindholm <linmag7@...il.com>
Suggested-by: "Maciej W. Rozycki" <macro@...am.me.uk>
Signed-off-by: Ivan Kokshaysky <ink@...een.parts>
---
 arch/alpha/kernel/entry.S | 20 ++++++++++----------
 arch/alpha/kernel/traps.c |  2 +-
 arch/alpha/mm/fault.c     |  4 ++--
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/alpha/kernel/entry.S b/arch/alpha/kernel/entry.S
index 6fb38365539d..f4d41b4538c2 100644
--- a/arch/alpha/kernel/entry.S
+++ b/arch/alpha/kernel/entry.S
@@ -194,8 +194,8 @@ CFI_END_OSF_FRAME entArith
 CFI_START_OSF_FRAME entMM
 	SAVE_ALL
 /* save $9 - $15 so the inline exception code can manipulate them.  */
-	subq	$sp, 56, $sp
-	.cfi_adjust_cfa_offset	56
+	subq	$sp, 64, $sp
+	.cfi_adjust_cfa_offset	64
 	stq	$9, 0($sp)
 	stq	$10, 8($sp)
 	stq	$11, 16($sp)
@@ -210,7 +210,7 @@ CFI_START_OSF_FRAME entMM
 	.cfi_rel_offset	$13, 32
 	.cfi_rel_offset	$14, 40
 	.cfi_rel_offset	$15, 48
-	addq	$sp, 56, $19
+	addq	$sp, 64, $19
 /* handle the fault */
 	lda	$8, 0x3fff
 	bic	$sp, $8, $8
@@ -223,7 +223,7 @@ CFI_START_OSF_FRAME entMM
 	ldq	$13, 32($sp)
 	ldq	$14, 40($sp)
 	ldq	$15, 48($sp)
-	addq	$sp, 56, $sp
+	addq	$sp, 64, $sp
 	.cfi_restore	$9
 	.cfi_restore	$10
 	.cfi_restore	$11
@@ -231,7 +231,7 @@ CFI_START_OSF_FRAME entMM
 	.cfi_restore	$13
 	.cfi_restore	$14
 	.cfi_restore	$15
-	.cfi_adjust_cfa_offset	-56
+	.cfi_adjust_cfa_offset	-64
 /* finish up the syscall as normal.  */
 	br	ret_from_sys_call
 CFI_END_OSF_FRAME entMM
@@ -378,8 +378,8 @@ entUnaUser:
 	.cfi_restore	$0
 	.cfi_adjust_cfa_offset	-256
 	SAVE_ALL		/* setup normal kernel stack */
-	lda	$sp, -56($sp)
-	.cfi_adjust_cfa_offset	56
+	lda	$sp, -64($sp)
+	.cfi_adjust_cfa_offset	64
 	stq	$9, 0($sp)
 	stq	$10, 8($sp)
 	stq	$11, 16($sp)
@@ -395,7 +395,7 @@ entUnaUser:
 	.cfi_rel_offset	$14, 40
 	.cfi_rel_offset	$15, 48
 	lda	$8, 0x3fff
-	addq	$sp, 56, $19
+	addq	$sp, 64, $19
 	bic	$sp, $8, $8
 	jsr	$26, do_entUnaUser
 	ldq	$9, 0($sp)
@@ -405,7 +405,7 @@ entUnaUser:
 	ldq	$13, 32($sp)
 	ldq	$14, 40($sp)
 	ldq	$15, 48($sp)
-	lda	$sp, 56($sp)
+	lda	$sp, 64($sp)
 	.cfi_restore	$9
 	.cfi_restore	$10
 	.cfi_restore	$11
@@ -413,7 +413,7 @@ entUnaUser:
 	.cfi_restore	$13
 	.cfi_restore	$14
 	.cfi_restore	$15
-	.cfi_adjust_cfa_offset	-56
+	.cfi_adjust_cfa_offset	-64
 	br	ret_from_sys_call
 CFI_END_OSF_FRAME entUna
 
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index a9a38c80c4a7..7004397937cf 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -649,7 +649,7 @@ s_reg_to_mem (unsigned long s_reg)
 static int unauser_reg_offsets[32] = {
 	R(r0), R(r1), R(r2), R(r3), R(r4), R(r5), R(r6), R(r7), R(r8),
 	/* r9 ... r15 are stored in front of regs.  */
-	-56, -48, -40, -32, -24, -16, -8,
+	-64, -56, -48, -40, -32, -24, -16,	/* padding at -8 */
 	R(r16), R(r17), R(r18),
 	R(r19), R(r20), R(r21), R(r22), R(r23), R(r24), R(r25), R(r26),
 	R(r27), R(r28), R(gp),
diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 8c9850437e67..a9816bbc9f34 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -78,8 +78,8 @@ __load_new_mm_context(struct mm_struct *next_mm)
 
 /* Macro for exception fixup code to access integer registers.  */
 #define dpf_reg(r)							\
-	(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 :	\
-				 (r) <= 18 ? (r)+10 : (r)-10])
+	(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-17 :	\
+				 (r) <= 18 ? (r)+11 : (r)-10])
 
 asmlinkage void
 do_page_fault(unsigned long address, unsigned long mmcsr,
-- 
2.39.5