linux-kernel - Re: [PATCH 4.4 17/70] crypto: arm64/sha - avoid non-standard inline asm tricks

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Date:   Mon, 23 Nov 2020 13:49:07 -0700
From:   dann frazier <dann.frazier@...onical.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: Re: [PATCH 4.4 17/70] crypto: arm64/sha - avoid non-standard inline
 asm tricks

On Mon, Nov 26, 2018 at 11:50:32AM +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.

fyi, I bisected a regression down to this commit. This apparently
causes an ADR_PREL_PG_HI21 relocation to be added to the sha{1,2}_ce
modules. Back in 4.4 ADR_PREL_PG_HI21 relocations were forbidden if
built with CONFIG_ARM64_ERRATUM_843419=y, so now the sha{1,2}_ce modules
fail to load:

[   37.866250] module sha1_ce: unsupported RELA relocation: 275

Looks like it should be an issue for 4.14.y as well, but I haven't yet
tested it.

  -dann

> From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> 
> commit f4857f4c2ee9aa4e2aacac1a845352b00197fb57 upstream.
> 
> Replace the inline asm which exports struct offsets as ELF symbols
> with proper const variables exposing the same values. This works
> around an issue with Clang which does not interpret the "i" (or "I")
> constraints in the same way as GCC.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Tested-by: Matthias Kaehlcke <mka@...omium.org>
> Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  arch/arm64/crypto/sha1-ce-core.S |    6 ++++--
>  arch/arm64/crypto/sha1-ce-glue.c |   11 +++--------
>  arch/arm64/crypto/sha2-ce-core.S |    6 ++++--
>  arch/arm64/crypto/sha2-ce-glue.c |   13 +++++--------
>  4 files changed, 16 insertions(+), 20 deletions(-)
> 
> --- a/arch/arm64/crypto/sha1-ce-core.S
> +++ b/arch/arm64/crypto/sha1-ce-core.S
> @@ -82,7 +82,8 @@ ENTRY(sha1_ce_transform)
>  	ldr		dgb, [x0, #16]
>  
>  	/* load sha1_ce_state::finalize */
> -	ldr		w4, [x0, #:lo12:sha1_ce_offsetof_finalize]
> +	ldr_l		w4, sha1_ce_offsetof_finalize, x4
> +	ldr		w4, [x0, x4]
>  
>  	/* load input */
>  0:	ld1		{v8.4s-v11.4s}, [x1], #64
> @@ -132,7 +133,8 @@ CPU_LE(	rev32		v11.16b, v11.16b	)
>  	 * the padding is handled by the C code in that case.
>  	 */
>  	cbz		x4, 3f
> -	ldr		x4, [x0, #:lo12:sha1_ce_offsetof_count]
> +	ldr_l		w4, sha1_ce_offsetof_count, x4
> +	ldr		x4, [x0, x4]
>  	movi		v9.2d, #0
>  	mov		x8, #0x80000000
>  	movi		v10.2d, #0
> --- a/arch/arm64/crypto/sha1-ce-glue.c
> +++ b/arch/arm64/crypto/sha1-ce-glue.c
> @@ -17,9 +17,6 @@
>  #include <linux/crypto.h>
>  #include <linux/module.h>
>  
> -#define ASM_EXPORT(sym, val) \
> -	asm(".globl " #sym "; .set " #sym ", %0" :: "I"(val));
> -
>  MODULE_DESCRIPTION("SHA1 secure hash using ARMv8 Crypto Extensions");
>  MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@...aro.org>");
>  MODULE_LICENSE("GPL v2");
> @@ -32,6 +29,9 @@ struct sha1_ce_state {
>  asmlinkage void sha1_ce_transform(struct sha1_ce_state *sst, u8 const *src,
>  				  int blocks);
>  
> +const u32 sha1_ce_offsetof_count = offsetof(struct sha1_ce_state, sst.count);
> +const u32 sha1_ce_offsetof_finalize = offsetof(struct sha1_ce_state, finalize);
> +
>  static int sha1_ce_update(struct shash_desc *desc, const u8 *data,
>  			  unsigned int len)
>  {
> @@ -52,11 +52,6 @@ static int sha1_ce_finup(struct shash_de
>  	struct sha1_ce_state *sctx = shash_desc_ctx(desc);
>  	bool finalize = !sctx->sst.count && !(len % SHA1_BLOCK_SIZE);
>  
> -	ASM_EXPORT(sha1_ce_offsetof_count,
> -		   offsetof(struct sha1_ce_state, sst.count));
> -	ASM_EXPORT(sha1_ce_offsetof_finalize,
> -		   offsetof(struct sha1_ce_state, finalize));
> -
>  	/*
>  	 * Allow the asm code to perform the finalization if there is no
>  	 * partial data and the input is a round multiple of the block size.
> --- a/arch/arm64/crypto/sha2-ce-core.S
> +++ b/arch/arm64/crypto/sha2-ce-core.S
> @@ -88,7 +88,8 @@ ENTRY(sha2_ce_transform)
>  	ld1		{dgav.4s, dgbv.4s}, [x0]
>  
>  	/* load sha256_ce_state::finalize */
> -	ldr		w4, [x0, #:lo12:sha256_ce_offsetof_finalize]
> +	ldr_l		w4, sha256_ce_offsetof_finalize, x4
> +	ldr		w4, [x0, x4]
>  
>  	/* load input */
>  0:	ld1		{v16.4s-v19.4s}, [x1], #64
> @@ -136,7 +137,8 @@ CPU_LE(	rev32		v19.16b, v19.16b	)
>  	 * the padding is handled by the C code in that case.
>  	 */
>  	cbz		x4, 3f
> -	ldr		x4, [x0, #:lo12:sha256_ce_offsetof_count]
> +	ldr_l		w4, sha256_ce_offsetof_count, x4
> +	ldr		x4, [x0, x4]
>  	movi		v17.2d, #0
>  	mov		x8, #0x80000000
>  	movi		v18.2d, #0
> --- a/arch/arm64/crypto/sha2-ce-glue.c
> +++ b/arch/arm64/crypto/sha2-ce-glue.c
> @@ -17,9 +17,6 @@
>  #include <linux/crypto.h>
>  #include <linux/module.h>
>  
> -#define ASM_EXPORT(sym, val) \
> -	asm(".globl " #sym "; .set " #sym ", %0" :: "I"(val));
> -
>  MODULE_DESCRIPTION("SHA-224/SHA-256 secure hash using ARMv8 Crypto Extensions");
>  MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@...aro.org>");
>  MODULE_LICENSE("GPL v2");
> @@ -32,6 +29,11 @@ struct sha256_ce_state {
>  asmlinkage void sha2_ce_transform(struct sha256_ce_state *sst, u8 const *src,
>  				  int blocks);
>  
> +const u32 sha256_ce_offsetof_count = offsetof(struct sha256_ce_state,
> +					      sst.count);
> +const u32 sha256_ce_offsetof_finalize = offsetof(struct sha256_ce_state,
> +						 finalize);
> +
>  static int sha256_ce_update(struct shash_desc *desc, const u8 *data,
>  			    unsigned int len)
>  {
> @@ -52,11 +54,6 @@ static int sha256_ce_finup(struct shash_
>  	struct sha256_ce_state *sctx = shash_desc_ctx(desc);
>  	bool finalize = !sctx->sst.count && !(len % SHA256_BLOCK_SIZE);
>  
> -	ASM_EXPORT(sha256_ce_offsetof_count,
> -		   offsetof(struct sha256_ce_state, sst.count));
> -	ASM_EXPORT(sha256_ce_offsetof_finalize,
> -		   offsetof(struct sha256_ce_state, finalize));
> -
>  	/*
>  	 * Allow the asm code to perform the finalization if there is no
>  	 * partial data and the input is a round multiple of the block size.
> 
>