lkml.org 
[lkml]   [2022]   [Jul]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC PATCH 2/6] modpost: deduplicate section_rel[a]()
Date
Now both functions are almost identical, and we can again generalize
the relocation types Elf_Rela/Elf_Rel with Elf_Rela, and handle some
differences with conditionals on section header type (SHT_RELA/REL).

The important bit is to make sure the loop increment uses the right
size for pointer arithmethic.

The original reason for split functions to make program logic easier
to follow; commit 5b24c0715fc4 ("kbuild: code refactoring in modpost").

Hopefully these 2 commits may help improving that, without an impact
in understanding the code due to generalization of relocation types.

Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
---
scripts/mod/modpost.c | 61 ++++++++++++++++---------------------------
1 file changed, 23 insertions(+), 38 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 4c1038dccae0..d1ed67fa290b 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1794,63 +1794,49 @@ static int get_relx_sym(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *rela,
return 0;
}

-static void section_rela(const char *modname, struct elf_info *elf,
+/* The caller must ensure sechdr->sh_type == SHT_RELA or SHT_REL. */
+static void section_relx(const char *modname, struct elf_info *elf,
Elf_Shdr *sechdr)
{
Elf_Sym *sym;
- Elf_Rela *rela;
+ Elf_Rela *relx; /* access .r_addend in SHT_RELA _only_! */
Elf_Rela r;
+ size_t relx_size;
const char *fromsec;

Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset;
Elf_Rela *stop = (void *)start + sechdr->sh_size;

fromsec = sech_name(elf, sechdr);
- fromsec += strlen(".rela");
+ if (sechdr->sh_type == SHT_RELA) {
+ relx_size = sizeof(Elf_Rela);
+ fromsec += strlen(".rela");
+ } else if (sechdr->sh_type == SHT_REL) {
+ relx_size = sizeof(Elf_Rel);
+ fromsec += strlen(".rel");
+ } else {
+ error("%s: [%s.ko] not relocation section\n", fromsec, modname);
+ return;
+ }
+
/* if from section (name) is know good then skip it */
if (match(fromsec, section_white_list))
return;

- for (rela = start; rela < stop; rela++) {
- if (get_relx_sym(elf, sechdr, rela, &r, &sym))
+ for (relx = start; relx < stop; relx = (void *)relx + relx_size) {
+ if (get_relx_sym(elf, sechdr, relx, &r, &sym))
continue;

switch (elf->hdr->e_machine) {
case EM_RISCV:
- if (!strcmp("__ex_table", fromsec) &&
+ if (sechdr->sh_type == SHT_RELA &&
+ !strcmp("__ex_table", fromsec) &&
ELF_R_TYPE(r.r_info) == R_RISCV_SUB32)
continue;
break;
}

- if (is_second_extable_reloc(start, rela, fromsec))
- find_extable_entry_size(fromsec, &r);
- check_section_mismatch(modname, elf, &r, sym, fromsec);
- }
-}
-
-static void section_rel(const char *modname, struct elf_info *elf,
- Elf_Shdr *sechdr)
-{
- Elf_Sym *sym;
- Elf_Rel *rel;
- Elf_Rela r;
- const char *fromsec;
-
- Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset;
- Elf_Rel *stop = (void *)start + sechdr->sh_size;
-
- fromsec = sech_name(elf, sechdr);
- fromsec += strlen(".rel");
- /* if from section (name) is know good then skip it */
- if (match(fromsec, section_white_list))
- return;
-
- for (rel = start; rel < stop; rel++) {
- if (get_relx_sym(elf, sechdr, (Elf_Rela *)rel, &r, &sym)
- continue;
-
- if (is_second_extable_reloc(start, rel, fromsec))
+ if (is_second_extable_reloc(start, relx, fromsec))
find_extable_entry_size(fromsec, &r);
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
@@ -1877,10 +1863,9 @@ static void check_sec_ref(const char *modname, struct elf_info *elf)
for (i = 0; i < elf->num_sections; i++) {
check_section(modname, elf, &elf->sechdrs[i]);
/* We want to process only relocation sections and not .init */
- if (sechdrs[i].sh_type == SHT_RELA)
- section_rela(modname, elf, &elf->sechdrs[i]);
- else if (sechdrs[i].sh_type == SHT_REL)
- section_rel(modname, elf, &elf->sechdrs[i]);
+ if (sechdrs[i].sh_type == SHT_RELA ||
+ sechdrs[i].sh_type == SHT_REL)
+ section_relx(modname, elf, &elf->sechdrs[i]);
}
}

--
2.25.1
\
 
 \ /
  Last update: 2022-07-22 04:24    [W:0.116 / U:1.576 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site