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

Conor.Dooley
2022-09-04T10:36:52Z

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):

-- >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