[PATCH 07/14] scripts/sorttable: Replace Elf_Shdr Macro with a union

Steven Rostedt
2025-01-02T18:59:47Z

From: Steven Rostedt <rostedt@goodmis.org>

In order to remove the double #include of sorttable.h for 64 and 32 bit
to create duplicate functions for both, replace the Elf_Shdr macro with a
union that defines both Elf64_Shdr and Elf32_Shdr, with field e64 for the
64bit version, and e32 for the 32bit version.

It can then use the macro etype to get the proper value.

This will eventually be replaced with just single functions that can
handle both 32bit and 64bit ELF parsing.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
scripts/sorttable.c | 10 ++++++
scripts/sorttable.h | 74 +++++++++++++++++++++++++--------------------
2 files changed, 51 insertions(+), 33 deletions(-)

diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 67cbbfc8214d..94497b8ab04c 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -69,6 +69,11 @@ typedef union {
Elf64_Ehdr e64;
} Elf_Ehdr;

+typedef union {
+ Elf32_Shdr e32;
+ Elf64_Shdr e64;
+} Elf_Shdr;
+
static uint32_t (*r)(const uint32_t *);
static uint16_t (*r2)(const uint16_t *);
static uint64_t (*r8)(const uint64_t *);
@@ -198,6 +203,11 @@ static int compare_extable_64(const void *a, const void *b)
return av > bv;
}

+static inline void *get_index(void *start, int entsize, int index)
+{
+ return start + (entsize * index);
+}
+
/* 32 bit and 64 bit are very similar */
#include "sorttable.h"
#define SORTTABLE_64
diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index eff204958ffc..034ce8560dad 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -23,7 +23,6 @@
#undef sort_mcount_loc
#undef elf_mcount_loc
#undef do_sort
-#undef Elf_Shdr
#undef Elf_Sym
#undef ELF_ST_TYPE
#undef uint_t
@@ -37,7 +36,6 @@
# define sort_mcount_loc sort_mcount_loc_64
# define elf_mcount_loc elf_mcount_loc_64
# define do_sort do_sort_64
-# define Elf_Shdr Elf64_Shdr
# define Elf_Sym Elf64_Sym
# define ELF_ST_TYPE ELF64_ST_TYPE
# define uint_t uint64_t
@@ -50,7 +48,6 @@
# define sort_mcount_loc sort_mcount_loc_32
# define elf_mcount_loc elf_mcount_loc_32
# define do_sort do_sort_32
-# define Elf_Shdr Elf32_Shdr
# define Elf_Sym Elf32_Sym
# define ELF_ST_TYPE ELF32_ST_TYPE
# define uint_t uint32_t
@@ -168,8 +165,8 @@ struct elf_mcount_loc {
static void *sort_mcount_loc(void *arg)
{
struct elf_mcount_loc *emloc = (struct elf_mcount_loc *)arg;
- uint_t offset = emloc->start_mcount_loc - _r(&(emloc->init_data_sec)->sh_addr)
- + _r(&(emloc->init_data_sec)->sh_offset);
+ uint_t offset = emloc->start_mcount_loc - _r(&(emloc->init_data_sec)->etype.sh_addr)
+ + _r(&(emloc->init_data_sec)->etype.sh_offset);
uint_t count = emloc->stop_mcount_loc - emloc->start_mcount_loc;
unsigned char *start_loc = (void *)emloc->ehdr + offset;

@@ -219,10 +216,11 @@ static int do_sort(Elf_Ehdr *ehdr,
table_sort_t custom_sort)
{
int rc = -1;
- Elf_Shdr *s, *shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->etype.e_shoff));
+ Elf_Shdr *shdr_start;
Elf_Shdr *strtab_sec = NULL;
Elf_Shdr *symtab_sec = NULL;
Elf_Shdr *extab_sec = NULL;
+ Elf_Shdr *string_sec;
Elf_Sym *sym;
const Elf_Sym *symtab;
Elf32_Word *symtab_shndx = NULL;
@@ -232,7 +230,10 @@ static int do_sort(Elf_Ehdr *ehdr,
const char *secstrings;
const char *strtab;
char *extab_image;
+ int sort_need_index;
+ int shentsize;
int idx;
+ int i;
unsigned int shnum;
unsigned int shstrndx;
#ifdef MCOUNT_SORT_ENABLED
@@ -246,34 +247,40 @@ static int do_sort(Elf_Ehdr *ehdr,
unsigned int orc_num_entries = 0;
#endif

+ shdr_start = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->etype.e_shoff));
+ shentsize = r2(&ehdr->etype.e_shentsize);
+
shstrndx = r2(&ehdr->etype.e_shstrndx);
if (shstrndx == SHN_XINDEX)
- shstrndx = r(&shdr[0].sh_link);
- secstrings = (const char *)ehdr + _r(&shdr[shstrndx].sh_offset);
+ shstrndx = r(&shdr_start->etype.sh_link);
+ string_sec = get_index(shdr_start, shentsize, shstrndx);
+ secstrings = (const char *)ehdr + _r(&string_sec->etype.sh_offset);

shnum = r2(&ehdr->etype.e_shnum);
if (shnum == SHN_UNDEF)
- shnum = _r(&shdr[0].sh_size);
+ shnum = _r(&shdr_start->etype.sh_size);
+
+ for (i = 0; i < shnum; i++) {
+ Elf_Shdr *shdr = get_index(shdr_start, shentsize, i);

- for (s = shdr; s < shdr + shnum; s++) {
- idx = r(&s->sh_name);
+ idx = r(&shdr->etype.sh_name);
if (!strcmp(secstrings + idx, "__ex_table"))
- extab_sec = s;
+ extab_sec = shdr;
if (!strcmp(secstrings + idx, ".symtab"))
- symtab_sec = s;
+ symtab_sec = shdr;
if (!strcmp(secstrings + idx, ".strtab"))
- strtab_sec = s;
+ strtab_sec = shdr;

- if (r(&s->sh_type) == SHT_SYMTAB_SHNDX)
+ if (r(&shdr->etype.sh_type) == SHT_SYMTAB_SHNDX)
symtab_shndx = (Elf32_Word *)((const char *)ehdr +
- _r(&s->sh_offset));
+ _r(&shdr->etype.sh_offset));

#ifdef MCOUNT_SORT_ENABLED
/* locate the .init.data section in vmlinux */
if (!strcmp(secstrings + idx, ".init.data")) {
get_mcount_loc(&_start_mcount_loc, &_stop_mcount_loc);
mstruct.ehdr = ehdr;
- mstruct.init_data_sec = s;
+ mstruct.init_data_sec = shdr;
mstruct.start_mcount_loc = _start_mcount_loc;
mstruct.stop_mcount_loc = _stop_mcount_loc;
}
@@ -282,14 +289,14 @@ static int do_sort(Elf_Ehdr *ehdr,
#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
/* locate the ORC unwind tables */
if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
- orc_ip_size = _r(&s->sh_size);
+ orc_ip_size = _r(&shdr->etype.sh_size);
g_orc_ip_table = (int *)((void *)ehdr +
- _r(&s->sh_offset));
+ _r(&shdr->etype.sh_offset));
}
if (!strcmp(secstrings + idx, ".orc_unwind")) {
- orc_size = _r(&s->sh_size);
+ orc_size = _r(&shdr->etype.sh_size);
g_orc_table = (struct orc_entry *)((void *)ehdr +
- _r(&s->sh_offset));
+ _r(&shdr->etype.sh_offset));
}
#endif
} /* for loop */
@@ -352,22 +359,22 @@ static int do_sort(Elf_Ehdr *ehdr,
goto out;
}

- extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
- strtab = (const char *)ehdr + _r(&strtab_sec->sh_offset);
+ extab_image = (void *)ehdr + _r(&extab_sec->etype.sh_offset);
+ strtab = (const char *)ehdr + _r(&strtab_sec->etype.sh_offset);
symtab = (const Elf_Sym *)((const char *)ehdr +
- _r(&symtab_sec->sh_offset));
+ _r(&symtab_sec->etype.sh_offset));

if (custom_sort) {
- custom_sort(extab_image, _r(&extab_sec->sh_size));
+ custom_sort(extab_image, _r(&extab_sec->etype.sh_size));
} else {
- int num_entries = _r(&extab_sec->sh_size) / extable_ent_size;
+ int num_entries = _r(&extab_sec->etype.sh_size) / extable_ent_size;
qsort(extab_image, num_entries,
extable_ent_size, compare_extable);
}

/* find the flag main_extable_sort_needed */
- for (sym = (void *)ehdr + _r(&symtab_sec->sh_offset);
- sym < sym + _r(&symtab_sec->sh_size) / sizeof(Elf_Sym);
+ for (sym = (void *)ehdr + _r(&symtab_sec->etype.sh_offset);
+ sym < sym + _r(&symtab_sec->etype.sh_size) / sizeof(Elf_Sym);
sym++) {
if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
continue;
@@ -385,13 +392,14 @@ static int do_sort(Elf_Ehdr *ehdr,
goto out;
}

- sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
- sort_needed_sym - symtab,
- symtab_shndx)];
+ sort_need_index = get_secindex(r2(&sym->st_shndx),
+ sort_needed_sym - symtab,
+ symtab_shndx);
+ sort_needed_sec = get_index(shdr_start, shentsize, sort_need_index);
sort_needed_loc = (void *)ehdr +
- _r(&sort_needed_sec->sh_offset) +
+ _r(&sort_needed_sec->etype.sh_offset) +
_r(&sort_needed_sym->st_value) -
- _r(&sort_needed_sec->sh_addr);
+ _r(&sort_needed_sec->etype.sh_addr);

/* extable has been sorted, clear the flag */
w(0, sort_needed_loc);
--
2.45.2