Re: [PATCH V2 5/6] riscv: elf_kexec: Fixup compile warning

Conor.Dooley
2022-09-04T11:13:27Z

On 04/09/2022 11:56, Guo Ren wrote:
> On Sun, Sep 4, 2022 at 6:36 PM <Conor.Dooley@microchip.com> wrote:
>>
>> On 04/09/2022 08:26, guoren@kernel.org wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>
>>> From: Guo Ren <guoren@linux.alibaba.com>
>>>
>>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1
>>> O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/
>>>
>>> ../arch/riscv/kernel/elf_kexec.c: In function 'elf_kexec_load':
>>> ../arch/riscv/kernel/elf_kexec.c:185:23: warning: variable
>>> 'kernel_start' set but not used [-Wunused-but-set-variable]
>>> 185 | unsigned long kernel_start;
>>> | ^~~~~~~~~~~~
>>>
>>> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
>>> Signed-off-by: Guo Ren <guoren@kernel.org>
>>> Reported-by: kernel test robot <lkp@intel.com>
>>
>> Is this then a
>> Fixes: 838b3e28488f ("RISC-V: Load purgatory in kexec_file")
>> ?
>>
>> Could you also add something like:
>> "If CONFIG_CRYTPO is not enabled, ...." to explain why this
>> may be unused?
>>
>>> ---
>>> arch/riscv/kernel/elf_kexec.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
>>> index 0cb94992c15b..bba3723a0914 100644
>>> --- a/arch/riscv/kernel/elf_kexec.c
>>> +++ b/arch/riscv/kernel/elf_kexec.c
>>> @@ -182,7 +182,9 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
>>> unsigned long new_kernel_pbase = 0UL;
>>> unsigned long initrd_pbase = 0UL;
>>> unsigned long headers_sz;
>>> +#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
>>> unsigned long kernel_start;
>>> +#endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
>>> void *fdt, *headers;
>>> struct elfhdr ehdr;
>>> struct kexec_buf kbuf;
>>> @@ -197,7 +199,9 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
>>> &old_kernel_pbase, &new_kernel_pbase);
>>> if (ret)
>>> goto out;
>>> +#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
>>> kernel_start = image->start;
>>> +#endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
>>
>> Instead of adding more #ifdefs to the file, could we instead just drop the
>> kernel_start variable? For the sake of compilation coverage, we could then
>> also do the following (build-tested only):
> Em... I prefer:

Uh, that works for me. The below diff is:
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

>
> diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
> index 0cb94992c15b..4b9264340b78 100644
> --- a/arch/riscv/kernel/elf_kexec.c
> +++ b/arch/riscv/kernel/elf_kexec.c
> @@ -198,7 +198,7 @@ static void *elf_kexec_load(struct kimage *image,
> char *kernel_buf,
> if (ret)
> goto out;
> kernel_start = image->start;
> - pr_notice("The entry point of kernel at 0x%lx\n", image->start);
> + pr_notice("The entry point of kernel at 0x%lx\n", kernel_start);
>
> /* Add the kernel binary to the image */
> ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
>
>
>>

Feel free to include this patch in your v3 then:
>> -- >8 --
>> From: Conor Dooley <conor.dooley@microchip.com>
>> Date: Sun, 4 Sep 2022 11:27:07 +0100
>> Subject: [PATCH] riscv: elf_kexec: replace ifdef with IS_ENABLED()
>>
>> IS_ENABLED() gives better compile time coverage than #ifdef.
>> Replace the ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY in elf_kexec_load()
>> since none of the code it guards uses a symbol that's missing if it
>> is not set.
>>
>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>> ---
>> arch/riscv/kernel/elf_kexec.c | 28 ++++++++++++++--------------
>> 1 file changed, 14 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
>> index 0cb94992c15b..29cbf655c474 100644
>> --- a/arch/riscv/kernel/elf_kexec.c
>> +++ b/arch/riscv/kernel/elf_kexec.c
>> @@ -248,21 +248,21 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
>> cmdline = modified_cmdline;
>> }
>>
>> -#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
>> - /* Add purgatory to the image */
>> - kbuf.top_down = true;
>> - kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
>> - ret = kexec_load_purgatory(image, &kbuf);
>> - if (ret) {
>> - pr_err("Error loading purgatory ret=%d\n", ret);
>> - goto out;
>> + if (IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY)) {
>> + /* Add purgatory to the image */
>> + kbuf.top_down = true;
>> + kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
>> + ret = kexec_load_purgatory(image, &kbuf);
>> + if (ret) {
>> + pr_err("Error loading purgatory ret=%d\n", ret);
>> + goto out;
>> + }
>> + ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
>> + &kernel_start,
>> + sizeof(kernel_start), 0);
>> + if (ret)
>> + pr_err("Error update purgatory ret=%d\n", ret);
>> }
>> - ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
>> - &kernel_start,
>> - sizeof(kernel_start), 0);
>> - if (ret)
>> - pr_err("Error update purgatory ret=%d\n", ret);
>> -#endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
>>
>> /* Add the initrd to the image */
>> if (initrd != NULL) {
>> --
>> 2.37.1
>>
>
>