Re: [PATCH] crypto: fix warnings from missing .note.GNU-stack

From: Heinrich Schuchardt
Date: Sun Jul 24 2022 - 13:01:15 EST

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On 7/23/22 12:37, Ard Biesheuvel wrote:

On Thu, 21 Jul 2022 at 22:48, Ben Dooks <ben-linux@xxxxxxxxx> wrote:

A lot of the assembly code in arch/arm/crypto is missing
a .note.GNU-stack section which is making a numbe of warnings
about implicit executable stack. This code does not look like
it does not need an executable stack, so silence the warnings
by adding a .section .note.GNU-stack to all these.

Since this is an empty section, it should be backwards compatible
with older linkers.

Fixes the following warnings:

arm-linux-gnueabihf-ld: warning: arch/arm/crypto/aes-cipher-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/aes-neonbs-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/sha1-armv4-large.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/sha1-armv7-neon.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/sha256-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/sha512-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/chacha-neon-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/aes-ce-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/sha1-ce-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/sha2-ce-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/ghash-ce-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
arm-linux-gnueabihf-ld: warning: arch/arm/crypto/crc32-ce-core.o: missing .note.GNU-stack section implies executable stack
arm-linux-gnueabihf-ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker

Signed-off-by: Ben Dooks <ben-linux@xxxxxxxxx>

Hello Ben,

This annotation is pointless in the kernel, as we never load any code
as ELF executables. We only load raw binaries or partially linked
objects, which don't carry this annotation, and we never use an
executable stack anyway.

So instead of adding these annotations, can we please just find a way
to shut up the linker?

Passing -zexecstack to gcc silences the warning.

This is what we use in U-Boot for ELF files that are only used as intermediaries to create EFI binaries.

---
arch/arm/crypto/aes-ce-core.S | 2 ++
arch/arm/crypto/aes-cipher-core.S | 2 ++
arch/arm/crypto/aes-neonbs-core.S | 3 +++
arch/arm/crypto/chacha-neon-core.S | 2 ++
arch/arm/crypto/chacha-scalar-core.S | 2 ++
arch/arm/crypto/crc32-ce-core.S | 2 ++
arch/arm/crypto/ghash-ce-core.S | 2 ++
arch/arm/crypto/sha1-armv4-large.S | 1 +
arch/arm/crypto/sha1-armv7-neon.S | 2 ++
arch/arm/crypto/sha1-ce-core.S | 2 ++
arch/arm/crypto/sha2-ce-core.S | 2 ++
arch/arm/crypto/sha256-armv4.pl | 1 +
arch/arm/crypto/sha512-armv4.pl | 1 +
13 files changed, 24 insertions(+)

diff --git a/arch/arm/crypto/aes-ce-core.S b/arch/arm/crypto/aes-ce-core.S
index 312428d83eed..4e570c6df9bb 100644
--- a/arch/arm/crypto/aes-ce-core.S
+++ b/arch/arm/crypto/aes-ce-core.S
@@ -711,3 +711,5 @@ ENDPROC(ce_aes_invert)
.byte 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf
.byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
.byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/aes-cipher-core.S b/arch/arm/crypto/aes-cipher-core.S
index 1da3f41359aa..11f10ee35487 100644
--- a/arch/arm/crypto/aes-cipher-core.S
+++ b/arch/arm/crypto/aes-cipher-core.S
@@ -199,3 +199,5 @@ ENDPROC(__aes_arm_encrypt)
ENTRY(__aes_arm_decrypt)
do_crypt iround, crypto_it_tab, crypto_aes_inv_sbox, 0
ENDPROC(__aes_arm_decrypt)
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/aes-neonbs-core.S b/arch/arm/crypto/aes-neonbs-core.S
index 7b61032f29fa..19197c0d635c 100644
--- a/arch/arm/crypto/aes-neonbs-core.S
+++ b/arch/arm/crypto/aes-neonbs-core.S
@@ -1041,3 +1041,6 @@ ENTRY(aesbs_xts_decrypt)
ldr ip, [sp, #8] // reorder final tweak?
__xts_crypt aesbs_decrypt8, q0, q1, q6, q4, q2, q7, q3, q5
ENDPROC(aesbs_xts_decrypt)
+
+.section .note.GNU-stack,"",%progbits

Would llvm-as understand this?

Best regards

Heinrich

+
diff --git a/arch/arm/crypto/chacha-neon-core.S b/arch/arm/crypto/chacha-neon-core.S
index 13d12f672656..a90690d32ad8 100644
--- a/arch/arm/crypto/chacha-neon-core.S
+++ b/arch/arm/crypto/chacha-neon-core.S
@@ -641,3 +641,5 @@ ENDPROC(chacha_4block_xor_neon)
.byte 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
.byte 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17
.byte 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/chacha-scalar-core.S b/arch/arm/crypto/chacha-scalar-core.S
index 083fe1ab96d0..81f94876f418 100644
--- a/arch/arm/crypto/chacha-scalar-core.S
+++ b/arch/arm/crypto/chacha-scalar-core.S
@@ -441,3 +441,5 @@ ENTRY(hchacha_block_arm)
1: _chacha_permute 12
b 0b
ENDPROC(hchacha_block_arm)
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/crc32-ce-core.S b/arch/arm/crypto/crc32-ce-core.S
index 3f13a76b9066..990c756c7487 100644
--- a/arch/arm/crypto/crc32-ce-core.S
+++ b/arch/arm/crypto/crc32-ce-core.S
@@ -304,3 +304,5 @@ ENDPROC(crc32_armv8_le)
ENTRY(crc32c_armv8_le)
__crc32 c
ENDPROC(crc32c_armv8_le)
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/ghash-ce-core.S b/arch/arm/crypto/ghash-ce-core.S
index 9f51e3fa4526..2f712b9d8b2b 100644
--- a/arch/arm/crypto/ghash-ce-core.S
+++ b/arch/arm/crypto/ghash-ce-core.S
@@ -337,3 +337,5 @@ ENTRY(pmull_ghash_update_p8)

ghash_update p8
ENDPROC(pmull_ghash_update_p8)
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/sha1-armv4-large.S b/arch/arm/crypto/sha1-armv4-large.S
index 1c8b685149f2..4e40132382b5 100644
--- a/arch/arm/crypto/sha1-armv4-large.S
+++ b/arch/arm/crypto/sha1-armv4-large.S
@@ -505,3 +505,4 @@ ENTRY(sha1_block_data_order)
ENDPROC(sha1_block_data_order)
.asciz "SHA1 block transform for ARMv4, CRYPTOGAMS by <appro@xxxxxxxxxxx>"
.align 2
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/sha1-armv7-neon.S b/arch/arm/crypto/sha1-armv7-neon.S
index 28d816a6a530..a554b1bb4ceb 100644
--- a/arch/arm/crypto/sha1-armv7-neon.S
+++ b/arch/arm/crypto/sha1-armv7-neon.S
@@ -632,3 +632,5 @@ ENTRY(sha1_transform_neon)
.Ldo_nothing:
bx lr
ENDPROC(sha1_transform_neon)
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/sha1-ce-core.S b/arch/arm/crypto/sha1-ce-core.S
index 8a702e051738..73353804c33f 100644
--- a/arch/arm/crypto/sha1-ce-core.S
+++ b/arch/arm/crypto/sha1-ce-core.S
@@ -121,3 +121,5 @@ ENTRY(sha1_ce_transform)
vstr dgbs, [r0, #16]
bx lr
ENDPROC(sha1_ce_transform)
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/sha2-ce-core.S b/arch/arm/crypto/sha2-ce-core.S
index b6369d2440a1..b5f20ab96690 100644
--- a/arch/arm/crypto/sha2-ce-core.S
+++ b/arch/arm/crypto/sha2-ce-core.S
@@ -121,3 +121,5 @@ ENTRY(sha2_ce_transform)
vst1.32 {dga-dgb}, [r0]
bx lr
ENDPROC(sha2_ce_transform)
+
+.section .note.GNU-stack,"",%progbits
diff --git a/arch/arm/crypto/sha256-armv4.pl b/arch/arm/crypto/sha256-armv4.pl
index f3a2b54efd4e..c12edbd99531 100644
--- a/arch/arm/crypto/sha256-armv4.pl
+++ b/arch/arm/crypto/sha256-armv4.pl
@@ -677,6 +677,7 @@ $code.=<<___;
#if __ARM_MAX_ARCH__>=7 && !defined(__KERNEL__)
.comm OPENSSL_armcap_P,4,4
#endif
+.section .note.GNU-stack,"",%progbits
___

open SELF,$0;
diff --git a/arch/arm/crypto/sha512-armv4.pl b/arch/arm/crypto/sha512-armv4.pl
index 2fc3516912fa..6411799b4d1d 100644
--- a/arch/arm/crypto/sha512-armv4.pl
+++ b/arch/arm/crypto/sha512-armv4.pl
@@ -639,6 +639,7 @@ $code.=<<___;
#if __ARM_MAX_ARCH__>=7 && !defined(__KERNEL__)
.comm OPENSSL_armcap_P,4,4
#endif
+.section .note.GNU-stack,"",%progbits
___

$code =~ s/\`([^\`]*)\`/eval $1/gem;
--
2.35.1

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