diff options
Diffstat (limited to 'target/linux/generic/patches-3.8/001-ARM-7668-1-fix-memset-related-crashes-caused-by-rece.patch')
| -rw-r--r-- | target/linux/generic/patches-3.8/001-ARM-7668-1-fix-memset-related-crashes-caused-by-rece.patch | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/target/linux/generic/patches-3.8/001-ARM-7668-1-fix-memset-related-crashes-caused-by-rece.patch b/target/linux/generic/patches-3.8/001-ARM-7668-1-fix-memset-related-crashes-caused-by-rece.patch new file mode 100644 index 0000000000..03bc2e4d1a --- /dev/null +++ b/target/linux/generic/patches-3.8/001-ARM-7668-1-fix-memset-related-crashes-caused-by-rece.patch @@ -0,0 +1,255 @@ +From 455bd4c430b0c0a361f38e8658a0d6cb469942b5 Mon Sep 17 00:00:00 2001 +From: Ivan Djelic <ivan.djelic@parrot.com> +Date: Wed, 6 Mar 2013 20:09:27 +0100 +Subject: [PATCH] ARM: 7668/1: fix memset-related crashes caused by recent GCC + (4.7.2) optimizations + +Recent GCC versions (e.g. GCC-4.7.2) perform optimizations based on +assumptions about the implementation of memset and similar functions. +The current ARM optimized memset code does not return the value of +its first argument, as is usually expected from standard implementations. + +For instance in the following function: + +void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter) +{ + memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter)); + waiter->magic = waiter; + INIT_LIST_HEAD(&waiter->list); +} + +compiled as: + +800554d0 <debug_mutex_lock_common>: +800554d0: e92d4008 push {r3, lr} +800554d4: e1a00001 mov r0, r1 +800554d8: e3a02010 mov r2, #16 ; 0x10 +800554dc: e3a01011 mov r1, #17 ; 0x11 +800554e0: eb04426e bl 80165ea0 <memset> +800554e4: e1a03000 mov r3, r0 +800554e8: e583000c str r0, [r3, #12] +800554ec: e5830000 str r0, [r3] +800554f0: e5830004 str r0, [r3, #4] +800554f4: e8bd8008 pop {r3, pc} + +GCC assumes memset returns the value of pointer 'waiter' in register r0; causing +register/memory corruptions. + +This patch fixes the return value of the assembly version of memset. +It adds a 'mov' instruction and merges an additional load+store into +existing load/store instructions. +For ease of review, here is a breakdown of the patch into 4 simple steps: + +Step 1 +====== +Perform the following substitutions: +ip -> r8, then +r0 -> ip, +and insert 'mov ip, r0' as the first statement of the function. +At this point, we have a memset() implementation returning the proper result, +but corrupting r8 on some paths (the ones that were using ip). + +Step 2 +====== +Make sure r8 is saved and restored when (! CALGN(1)+0) == 1: + +save r8: +- str lr, [sp, #-4]! ++ stmfd sp!, {r8, lr} + +and restore r8 on both exit paths: +- ldmeqfd sp!, {pc} @ Now <64 bytes to go. ++ ldmeqfd sp!, {r8, pc} @ Now <64 bytes to go. +(...) + tst r2, #16 + stmneia ip!, {r1, r3, r8, lr} +- ldr lr, [sp], #4 ++ ldmfd sp!, {r8, lr} + +Step 3 +====== +Make sure r8 is saved and restored when (! CALGN(1)+0) == 0: + +save r8: +- stmfd sp!, {r4-r7, lr} ++ stmfd sp!, {r4-r8, lr} + +and restore r8 on both exit paths: + bgt 3b +- ldmeqfd sp!, {r4-r7, pc} ++ ldmeqfd sp!, {r4-r8, pc} +(...) + tst r2, #16 + stmneia ip!, {r4-r7} +- ldmfd sp!, {r4-r7, lr} ++ ldmfd sp!, {r4-r8, lr} + +Step 4 +====== +Rewrite register list "r4-r7, r8" as "r4-r8". + +Signed-off-by: Ivan Djelic <ivan.djelic@parrot.com> +Reviewed-by: Nicolas Pitre <nico@linaro.org> +Signed-off-by: Dirk Behme <dirk.behme@gmail.com> +Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> +--- + arch/arm/lib/memset.S | 85 ++++++++++++++++++++++++++------------------------- + 1 file changed, 44 insertions(+), 41 deletions(-) + +diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S +index 650d5923ab83..d912e7397ecc 100644 +--- a/arch/arm/lib/memset.S ++++ b/arch/arm/lib/memset.S +@@ -19,9 +19,9 @@ + 1: subs r2, r2, #4 @ 1 do we have enough + blt 5f @ 1 bytes to align with? + cmp r3, #2 @ 1 +- strltb r1, [r0], #1 @ 1 +- strleb r1, [r0], #1 @ 1 +- strb r1, [r0], #1 @ 1 ++ strltb r1, [ip], #1 @ 1 ++ strleb r1, [ip], #1 @ 1 ++ strb r1, [ip], #1 @ 1 + add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3)) + /* + * The pointer is now aligned and the length is adjusted. Try doing the +@@ -29,10 +29,14 @@ + */ + + ENTRY(memset) +- ands r3, r0, #3 @ 1 unaligned? ++/* ++ * Preserve the contents of r0 for the return value. ++ */ ++ mov ip, r0 ++ ands r3, ip, #3 @ 1 unaligned? + bne 1b @ 1 + /* +- * we know that the pointer in r0 is aligned to a word boundary. ++ * we know that the pointer in ip is aligned to a word boundary. + */ + orr r1, r1, r1, lsl #8 + orr r1, r1, r1, lsl #16 +@@ -43,29 +47,28 @@ ENTRY(memset) + #if ! CALGN(1)+0 + + /* +- * We need an extra register for this loop - save the return address and +- * use the LR ++ * We need 2 extra registers for this loop - use r8 and the LR + */ +- str lr, [sp, #-4]! +- mov ip, r1 ++ stmfd sp!, {r8, lr} ++ mov r8, r1 + mov lr, r1 + + 2: subs r2, r2, #64 +- stmgeia r0!, {r1, r3, ip, lr} @ 64 bytes at a time. +- stmgeia r0!, {r1, r3, ip, lr} +- stmgeia r0!, {r1, r3, ip, lr} +- stmgeia r0!, {r1, r3, ip, lr} ++ stmgeia ip!, {r1, r3, r8, lr} @ 64 bytes at a time. ++ stmgeia ip!, {r1, r3, r8, lr} ++ stmgeia ip!, {r1, r3, r8, lr} ++ stmgeia ip!, {r1, r3, r8, lr} + bgt 2b +- ldmeqfd sp!, {pc} @ Now <64 bytes to go. ++ ldmeqfd sp!, {r8, pc} @ Now <64 bytes to go. + /* + * No need to correct the count; we're only testing bits from now on + */ + tst r2, #32 +- stmneia r0!, {r1, r3, ip, lr} +- stmneia r0!, {r1, r3, ip, lr} ++ stmneia ip!, {r1, r3, r8, lr} ++ stmneia ip!, {r1, r3, r8, lr} + tst r2, #16 +- stmneia r0!, {r1, r3, ip, lr} +- ldr lr, [sp], #4 ++ stmneia ip!, {r1, r3, r8, lr} ++ ldmfd sp!, {r8, lr} + + #else + +@@ -74,54 +77,54 @@ ENTRY(memset) + * whole cache lines at once. + */ + +- stmfd sp!, {r4-r7, lr} ++ stmfd sp!, {r4-r8, lr} + mov r4, r1 + mov r5, r1 + mov r6, r1 + mov r7, r1 +- mov ip, r1 ++ mov r8, r1 + mov lr, r1 + + cmp r2, #96 +- tstgt r0, #31 ++ tstgt ip, #31 + ble 3f + +- and ip, r0, #31 +- rsb ip, ip, #32 +- sub r2, r2, ip +- movs ip, ip, lsl #(32 - 4) +- stmcsia r0!, {r4, r5, r6, r7} +- stmmiia r0!, {r4, r5} +- tst ip, #(1 << 30) +- mov ip, r1 +- strne r1, [r0], #4 ++ and r8, ip, #31 ++ rsb r8, r8, #32 ++ sub r2, r2, r8 ++ movs r8, r8, lsl #(32 - 4) ++ stmcsia ip!, {r4, r5, r6, r7} ++ stmmiia ip!, {r4, r5} ++ tst r8, #(1 << 30) ++ mov r8, r1 ++ strne r1, [ip], #4 + + 3: subs r2, r2, #64 +- stmgeia r0!, {r1, r3-r7, ip, lr} +- stmgeia r0!, {r1, r3-r7, ip, lr} ++ stmgeia ip!, {r1, r3-r8, lr} ++ stmgeia ip!, {r1, r3-r8, lr} + bgt 3b +- ldmeqfd sp!, {r4-r7, pc} ++ ldmeqfd sp!, {r4-r8, pc} + + tst r2, #32 +- stmneia r0!, {r1, r3-r7, ip, lr} ++ stmneia ip!, {r1, r3-r8, lr} + tst r2, #16 +- stmneia r0!, {r4-r7} +- ldmfd sp!, {r4-r7, lr} ++ stmneia ip!, {r4-r7} ++ ldmfd sp!, {r4-r8, lr} + + #endif + + 4: tst r2, #8 +- stmneia r0!, {r1, r3} ++ stmneia ip!, {r1, r3} + tst r2, #4 +- strne r1, [r0], #4 ++ strne r1, [ip], #4 + /* + * When we get here, we've got less than 4 bytes to zero. We + * may have an unaligned pointer as well. + */ + 5: tst r2, #2 +- strneb r1, [r0], #1 +- strneb r1, [r0], #1 ++ strneb r1, [ip], #1 ++ strneb r1, [ip], #1 + tst r2, #1 +- strneb r1, [r0], #1 ++ strneb r1, [ip], #1 + mov pc, lr + ENDPROC(memset) +-- +1.8.3.2 + |