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fixup review comments

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Signed-off-by: Seth Jennings <sjenning@redhat.com>
This commit is contained in:
Seth Jennings 2014-04-22 11:01:01 -05:00
parent ab07805166
commit 47d4109f7e
1 changed files with 29 additions and 4 deletions
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33
kpatch-build/create-diff-object.c
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@ -971,7 +971,32 @@ void kpatch_write_inventory_file(struct kpatch_elf *kelf, char *outfile)
fclose(out);
}
void kpatch_regenerate_bug_table(struct kpatch_elf *kelf)
/*
* The format of section __bug_table is a table of struct bug_entry. Each
* bug_entry has three fields:
* - relocated address of instruction pointer at BUG
* - relocated address of string with filename
* - line number of the BUG
*
* Therefore, .rela__bug_table has two relocations per entry. The first
* relocation is that of the instruction pointer at the BUG. The second is the
* pointer to the filename string in .rodata.str1.1. These two related
* relocations we will call a "pair".
*
* This function goes through .rela__bug_table and finds pairs the refer to
* functions that have been marked as changed. If one is found, that pair is
* copied into the new version of the .rela__bug_table section. If no pairs
* are found, the bug table (both the __bug_table and .rela__bug_table
* sections) are considered unchanged and not copied into the final output.
*
* The __bug_table section is not modified and therefore will contains "blank"
* bug_entry slots i.e. ones that do not get relocated and therefore the IP
* fields are zero. While this wastes space, it doesn't hurt anything and
* keeps the code cleaner by not having to regenerate the __bug_table section
* as well.
*/
void kpatch_regenerate_bug_table_rela_section(struct kpatch_elf *kelf)
{
struct section *sec;
struct table table;
@ -979,7 +1004,7 @@ void kpatch_regenerate_bug_table(struct kpatch_elf *kelf)
int i, nr = 0, copynext = 0;
sec = find_section_by_name(&kelf->sections, ".rela__bug_table");
if (!sec || sec->status == SAME)
if (!sec)
return;
/* alloc buffer of original size (probably won't use it all) */
@ -1008,7 +1033,7 @@ void kpatch_regenerate_bug_table(struct kpatch_elf *kelf)
}
if (!nr) {
/* no changed functions references by bug table */
/* no changed functions referenced by bug table */
sec->status = SAME;
sec->base->status = SAME;
return;
@ -1381,7 +1406,7 @@ int main(int argc, char *argv[])
* in vmlinux can be linked to.
*/
kpatch_replace_sections_syms(kelf_patched);
kpatch_regenerate_bug_table(kelf_patched);
kpatch_regenerate_bug_table_rela_section(kelf_patched);
kpatch_include_standard_sections(kelf_patched);
if (!kpatch_include_changed_functions(kelf_patched)) {