Re: [PATCH 08/11] kexec_file: Simplify kexec_purgatory_setup_sechdrs 2

From: Dave Young
Date: Thu Mar 08 2018 - 22:18:22 EST


Hi,

On 02/26/18 at 04:16pm, Philipp Rudo wrote:
> The main loop currently uses quite a lot of variables to update the section
> headers. Some of them are unnecessary. So clean them up a little.
>

It looks better to use some patch subject eg below:
"Remove unnecessary variables in kexec_purgatory_setup_sechdrs"

> Signed-off-by: Philipp Rudo <prudo@xxxxxxxxxxxxxxxxxx>
> ---
> kernel/kexec_file.c | 34 ++++++++++++----------------------
> 1 file changed, 12 insertions(+), 22 deletions(-)
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index bb31a3b627c2..746b91e46e34 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -724,12 +724,8 @@ static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
> static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
> struct kexec_buf *kbuf)
> {
> - unsigned long curr_load_addr;
> - unsigned long load_addr;
> unsigned long bss_addr;
> unsigned long offset;
> - unsigned char *buf_addr;
> - unsigned char *src;
> Elf_Shdr *sechdrs;
> int i;
>
> @@ -762,20 +758,18 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
> sechdrs[i].sh_offset;
> }
>
> - /* Load SHF_ALLOC sections */
> - buf_addr = kbuf->buffer;
> - load_addr = curr_load_addr = kbuf->mem;
> - bss_addr = load_addr + kbuf->bufsz;
> + offset = 0;
> + bss_addr = kbuf->mem + kbuf->bufsz;
> kbuf->image->start = pi->ehdr->e_entry;
>
> for (i = 0; i < pi->ehdr->e_shnum; i++) {
> unsigned long align;
> + void *src, *dst;
>
> if (!(sechdrs[i].sh_flags & SHF_ALLOC))
> continue;
>
> align = sechdrs[i].sh_addralign;
> -
> if (sechdrs[i].sh_type == SHT_NOBITS) {
> bss_addr = ALIGN(bss_addr, align);
> sechdrs[i].sh_addr = bss_addr;
> @@ -783,31 +777,27 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
> continue;
> }
>
> - curr_load_addr = ALIGN(curr_load_addr, align);
> - offset = curr_load_addr - load_addr;
> - /* We already modifed ->sh_offset to keep src addr */
> - src = (char *)sechdrs[i].sh_offset;
> - memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
> -
> + offset = ALIGN(offset, align);
> if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
> pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
> pi->ehdr->e_entry < (sechdrs[i].sh_addr
> + sechdrs[i].sh_size)) {
> kbuf->image->start -= sechdrs[i].sh_addr;
> - kbuf->image->start += curr_load_addr
> + kbuf->image->start += kbuf->mem + offset;
> }
>
> - /* Store load address and source address of section */
> - sechdrs[i].sh_addr = curr_load_addr;
> + src = (void *)sechdrs[i].sh_offset;
> + dst = pi->purgatory_buf + offset;
> + memcpy(dst, src, sechdrs[i].sh_size);
> +
> + sechdrs[i].sh_addr = kbuf->mem + offset;
>
> /*
> * This section got copied to temporary buffer. Update
> * ->sh_offset accordingly.
> */
> - sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
> -
> - /* Advance to the next address */
> - curr_load_addr += sechdrs[i].sh_size;
> + sechdrs[i].sh_offset = (unsigned long)dst;
> + offset += sechdrs[i].sh_size;
> }
>
> return 0;
> --
> 2.13.5
>

Thanks
Dave