linux-kernel - Re: [PATCH] rseq/selftests: Fix riscv rseq_offset_deref

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Message-ID: <44f202e8-dc35-40aa-8dc3-2f2e4c28feda@efficios.com>
Date: Fri, 10 Jan 2025 11:22:16 -0500
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Stafford Horne <shorne@...il.com>, LKML <linux-kernel@...r.kernel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
 "Paul E. McKenney" <paulmck@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
 Shuah Khan <shuah@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>,
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 linux-kselftest@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH] rseq/selftests: Fix riscv rseq_offset_deref_addv inline
 asm

On 2025-01-02 23:03, Stafford Horne wrote:
> When working on OpenRISC support for restartable sequences I noticed
> and fixed these two issues with the riscv support bits.
> 
>   1 The 'inc' argument to RSEQ_ASM_OP_R_DEREF_ADDV was being implicitly
>     passed to the macro.  Fix this by adding 'inc' to the list of macro
>     arguments.
>   2 The inline asm input constraints for 'inc' and 'off' use "er",  The
>     riscv gcc port does not have an "e" constraint, this looks to be
>     copied from the x86 port.  Fix this by just using an "r" constraint.
> 
> I have compile tested this only for riscv.  However, the same fixes I
> use in the OpenRISC rseq selftests and everything passes with no issues.
> 
> Signed-off-by: Stafford Horne <shorne@...il.com>

Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>

> ---
>   tools/testing/selftests/rseq/rseq-riscv-bits.h | 6 +++---
>   tools/testing/selftests/rseq/rseq-riscv.h      | 2 +-
>   2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/rseq/rseq-riscv-bits.h b/tools/testing/selftests/rseq/rseq-riscv-bits.h
> index de31a0143139..f02f411d550d 100644
> --- a/tools/testing/selftests/rseq/rseq-riscv-bits.h
> +++ b/tools/testing/selftests/rseq/rseq-riscv-bits.h
> @@ -243,7 +243,7 @@ int RSEQ_TEMPLATE_IDENTIFIER(rseq_offset_deref_addv)(intptr_t *ptr, off_t off, i
>   #ifdef RSEQ_COMPARE_TWICE
>   				  RSEQ_ASM_CMP_CPU_ID(cpu_id, current_cpu_id, "%l[error1]")
>   #endif
> -				  RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, 3)
> +				  RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, inc, 3)
>   				  RSEQ_INJECT_ASM(4)
>   				  RSEQ_ASM_DEFINE_ABORT(4, abort)
>   				  : /* gcc asm goto does not allow outputs */
> @@ -251,8 +251,8 @@ int RSEQ_TEMPLATE_IDENTIFIER(rseq_offset_deref_addv)(intptr_t *ptr, off_t off, i
>   				    [current_cpu_id]		"m" (rseq_get_abi()->RSEQ_TEMPLATE_CPU_ID_FIELD),
>   				    [rseq_cs]			"m" (rseq_get_abi()->rseq_cs.arch.ptr),
>   				    [ptr]			"r" (ptr),
> -				    [off]			"er" (off),
> -				    [inc]			"er" (inc)
> +				    [off]			"r" (off),
> +				    [inc]			"r" (inc)
>   				    RSEQ_INJECT_INPUT
>   				  : "memory", RSEQ_ASM_TMP_REG_1
>   				    RSEQ_INJECT_CLOBBER
> diff --git a/tools/testing/selftests/rseq/rseq-riscv.h b/tools/testing/selftests/rseq/rseq-riscv.h
> index 37e598d0a365..67d544aaa9a3 100644
> --- a/tools/testing/selftests/rseq/rseq-riscv.h
> +++ b/tools/testing/selftests/rseq/rseq-riscv.h
> @@ -158,7 +158,7 @@ do {									\
>   	"bnez	" RSEQ_ASM_TMP_REG_1 ", 222b\n"				\
>   	"333:\n"
>   
> -#define RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, post_commit_label)		\
> +#define RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, inc, post_commit_label)	\
>   	"mv	" RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(ptr) "]\n"	\
>   	RSEQ_ASM_OP_R_ADD(off)						\
>   	REG_L	  RSEQ_ASM_TMP_REG_1 ", 0(" RSEQ_ASM_TMP_REG_1 ")\n"	\

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com