linux-kernel - Re: [PATCH v2 2/5] riscv: Use SYM_*() assembly macros instead of deprecated ones

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Message-ID: <da308888-0e47-4ca4-b318-8f089421dc0b@rivosinc.com>
Date:   Tue, 24 Oct 2023 20:03:52 +0200
From:   Clément Léger <cleger@...osinc.com>
To:     Andrew Jones <ajones@...tanamicro.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 2/5] riscv: Use SYM_*() assembly macros instead of
 deprecated ones



On 24/10/2023 17:23, Andrew Jones wrote:
> On Tue, Oct 24, 2023 at 03:26:52PM +0200, Clément Léger wrote:
> ...
>> diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S
>> index 09b47ebacf2e..3ab438f30d13 100644
>> --- a/arch/riscv/lib/uaccess.S
>> +++ b/arch/riscv/lib/uaccess.S
>> @@ -10,8 +10,7 @@
>>  	_asm_extable	100b, \lbl
>>  	.endm
>>  
>> -ENTRY(__asm_copy_to_user)
>> -ENTRY(__asm_copy_from_user)
>> +SYM_FUNC_START(__asm_copy_to_user)
>>  
>>  	/* Enable access to user memory */
>>  	li t6, SR_SUM
>> @@ -181,13 +180,13 @@ ENTRY(__asm_copy_from_user)
>>  	csrc CSR_STATUS, t6
>>  	sub a0, t5, a0
>>  	ret
>> -ENDPROC(__asm_copy_to_user)
>> -ENDPROC(__asm_copy_from_user)
>> +SYM_FUNC_END(__asm_copy_to_user)
>>  EXPORT_SYMBOL(__asm_copy_to_user)
>> +SYM_FUNC_ALIAS(__asm_copy_from_user, __asm_copy_to_user)
>>  EXPORT_SYMBOL(__asm_copy_from_user)
> 
> I didn't see any comment about the sharing of debug info among both the
> from and to functions. Assuming it isn't confusing in some way, then

Hi Andrew,

I did some testing with gdb and it seems to correctly assume that
__asm_copy_to_user maps to __asm_copy_from_user for debugging. The basic
tests that I did (breakpoints, disasm, etc) seems to show no sign of
problems for debugging. Were you thinking about other things specifically ?

Thanks,

Clément

> 
> Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
> 
> Thanks,
> drew