From: Philipp Rudo <prudo@xxxxxxxxxxxxxxxxxx> Subject: kernel/kexec_file.c: remove unneeded for-loop in kexec_purgatory_setup_sechdrs To update the entry point there is an extra loop over all section headers although this can be done in the main loop. So move it there and eliminate the extra loop and variable to store the 'entry section index'. Also, in the main loop, move the usual case, i.e. non-bss section, out of the extra if-block. Link: http://lkml.kernel.org/r/20180321112751.22196-8-prudo@xxxxxxxxxxxxxxxxxx Signed-off-by: Philipp Rudo <prudo@xxxxxxxxxxxxxxxxxx> Reviewed-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Acked-by: Dave Young <dyoung@xxxxxxxxxx> Cc: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/kexec_file.c | 76 ++++++++++++++++-------------------------- 1 file changed, 30 insertions(+), 46 deletions(-) diff -puN kernel/kexec_file.c~kexec_file-remove-unneeded-for-loop-in-kexec_purgatory_setup_sechdrs kernel/kexec_file.c --- a/kernel/kexec_file.c~kexec_file-remove-unneeded-for-loop-in-kexec_purgatory_setup_sechdrs +++ a/kernel/kexec_file.c @@ -792,7 +792,6 @@ static int kexec_purgatory_setup_sechdrs unsigned char *buf_addr; unsigned char *src; Elf_Shdr *sechdrs; - int entry_sidx = -1; int i; sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr)); @@ -824,32 +823,11 @@ static int kexec_purgatory_setup_sechdrs sechdrs[i].sh_offset; } - /* - * Identify entry point section and make entry relative to section - * start. - */ - kbuf->image->start = pi->ehdr->e_entry; - for (i = 0; i < pi->ehdr->e_shnum; i++) { - if (!(sechdrs[i].sh_flags & SHF_ALLOC)) - continue; - - if (!(sechdrs[i].sh_flags & SHF_EXECINSTR)) - continue; - - /* Make entry section relative */ - if (sechdrs[i].sh_addr <= pi->ehdr->e_entry && - ((sechdrs[i].sh_addr + sechdrs[i].sh_size) > - pi->ehdr->e_entry)) { - entry_sidx = i; - kbuf->image->start -= sechdrs[i].sh_addr; - break; - } - } - /* Load SHF_ALLOC sections */ buf_addr = kbuf->buffer; load_addr = curr_load_addr = kbuf->mem; bss_addr = load_addr + kbuf->bufsz; + kbuf->image->start = pi->ehdr->e_entry; for (i = 0; i < pi->ehdr->e_shnum; i++) { unsigned long align; @@ -858,34 +836,40 @@ static int kexec_purgatory_setup_sechdrs continue; align = sechdrs[i].sh_addralign; - if (sechdrs[i].sh_type != SHT_NOBITS) { - 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); - - /* Store load address and source address of section */ - sechdrs[i].sh_addr = curr_load_addr; - - /* - * 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; - } else { + + if (sechdrs[i].sh_type == SHT_NOBITS) { bss_addr = ALIGN(bss_addr, align); sechdrs[i].sh_addr = bss_addr; bss_addr += sechdrs[i].sh_size; + continue; } - } - /* Update entry point based on load address of text section */ - if (entry_sidx >= 0) - kbuf->image->start += sechdrs[entry_sidx].sh_addr; + 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); + + 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; + } + + /* Store load address and source address of section */ + sechdrs[i].sh_addr = curr_load_addr; + + /* + * 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; + } return 0; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
