The patch titled
Subject: kernel/kexec_file.c: remove unneeded for-loop in kexec_purgatory_setup_sechdrs
has been added to the -mm tree. Its filename is
kexec_file-remove-unneeded-for-loop-in-kexec_purgatory_setup_sechdrs.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kexec_file-remove-unneeded-for-loop-in-kexec_purgatory_setup_sechdrs.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kexec_file-remove-unneeded-for-loop-in-kexec_purgatory_setup_sechdrs.patch
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------------------------------------------------------
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>
Cc: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
Cc: Dave Young <dyoung@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
@@ -834,7 +834,6 @@ 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));
@@ -866,32 +865,11 @@ 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;
@@ -900,34 +878,40 @@ 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;
}
_
Patches currently in -mm which might be from prudo@xxxxxxxxxxxxxxxxxx are
kexec_file-silence-compile-warnings.patch
kexec_file-remove-checks-in-kexec_purgatory_load.patch
kexec_file-make-purgatory_info-ehdr-const.patch
kexec_file-search-symbols-in-read-only-kexec_purgatory.patch
kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations.patch
kexec_file-split-up-__kexec_load_puragory.patch
kexec_file-remove-unneeded-for-loop-in-kexec_purgatory_setup_sechdrs.patch
kexec_file-remove-unneeded-variables-in-kexec_purgatory_setup_sechdrs.patch
kexec_file-remove-mis-use-of-sh_offset-field-during-purgatory-load.patch
kexec_file-allow-archs-to-set-purgatory-load-address.patch
kexec_file-move-purgatories-sha256-to-common-code.patch
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