[PATCH v2 02/14] arm: add initjmp()

[Jerome Forissier]

On 2/28/25 14:05, Heinrich Schuchardt wrote:
> On 25.02.25 17:34, Jerome Forissier wrote:
>> Implement initjmp() for Arm.
>>
>> Signed-off-by: Jerome Forissier <jerome.forissier at linaro.org>
>> ---
>>   arch/Kconfig                  |  1 +
>>   arch/arm/include/asm/setjmp.h |  1 +
>>   arch/arm/lib/setjmp.S         | 11 +++++++++++
>>   arch/arm/lib/setjmp_aarch64.S |  9 +++++++++
>>   4 files changed, 22 insertions(+)
>>
>> diff --git a/arch/Kconfig b/arch/Kconfig
>> index 8d5b54031b3..57695fada8d 100644
>> --- a/arch/Kconfig
>> +++ b/arch/Kconfig
>> @@ -94,6 +94,7 @@ config ARC
>>   config ARM
>>       bool "ARM architecture"
>>       select HAVE_SETJMP
>> +    select HAVE_INITJMP
>>       select ARCH_SUPPORTS_LTO
>>       select CREATE_ARCH_SYMLINK
>>       select HAVE_PRIVATE_LIBGCC if !ARM64
>> diff --git a/arch/arm/include/asm/setjmp.h b/arch/arm/include/asm/setjmp.h
>> index 662bec86321..1ad5b500f2a 100644
>> --- a/arch/arm/include/asm/setjmp.h
>> +++ b/arch/arm/include/asm/setjmp.h
>> @@ -23,5 +23,6 @@ typedef struct jmp_buf_data jmp_buf[1];
>>
>>   int setjmp(jmp_buf jmp);
>>   void longjmp(jmp_buf jmp, int ret);
>> +int initjmp(jmp_buf jmp, void __noreturn (*func)(void), void *stack_top);
> 
> As this is not a standard function we cannot expect developers to know
> what it does and how to use it.
> 
> Please, provide Sphinx style documentation with the necessary information.

I agree on principle, but if I add documentation here then I should add the
same for all architectures. That being said the prototypes are already
duplicated so maybe consolidation is a question for another time.  I will
add Shpinx style doc to all 3 commits "{arm,riscv,sandbox}: add initjmp()".

As for usage, I think the best documentation is test/lib/initjmp.c added
by "test: lib: add initjmp() test".

Thanks,
-- 
Jerome

> 
> Best regards
> 
> Heinrich
> 
>>
>>   #endif /* _SETJMP_H_ */
>> diff --git a/arch/arm/lib/setjmp.S b/arch/arm/lib/setjmp.S
>> index 2f041aeef01..320ddea85f9 100644
>> --- a/arch/arm/lib/setjmp.S
>> +++ b/arch/arm/lib/setjmp.S
>> @@ -34,3 +34,14 @@ ENTRY(longjmp)
>>       ret  lr
>>   ENDPROC(longjmp)
>>   .popsection
>> +
>> +.pushsection .text.initjmp, "ax"
>> +ENTRY(initjmp)
>> +    stm  a1, {v1-v8}
>> +    /* a2: entry point address, a3: stack top */
>> +    str  a3, [a1, #32]  /* where setjmp would save sp */
>> +    str  a2, [a1, #36]  /* where setjmp would save lr */
>> +    mov  a1, #0
>> +    ret  lr
>> +ENDPROC(initjmp)
>> +.popsection
>> diff --git a/arch/arm/lib/setjmp_aarch64.S b/arch/arm/lib/setjmp_aarch64.S
>> index 1b8d000eb48..074320d25fb 100644
>> --- a/arch/arm/lib/setjmp_aarch64.S
>> +++ b/arch/arm/lib/setjmp_aarch64.S
>> @@ -39,3 +39,12 @@ ENTRY(longjmp)
>>       ret
>>   ENDPROC(longjmp)
>>   .popsection
>> +
>> +.pushsection .text.initjmp, "ax"
>> +ENTRY(initjmp)
>> +    /* x1: entry point address, x2: stack top */
>> +    stp x1, x2, [x0,#88]
>> +    mov  x0, #0
>> +    ret
>> +ENDPROC(initjmp)
>> +.popsection
>