Gh0st
/
linux
mirror of https://github.com/torvalds/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

genksyms: use uint32_t instead of unsigned long for calculating CRC 

Currently, 'unsigned long' is used for intermediate variables when
calculating CRCs.

The size of 'long' differs depending on the architecture: it is 32 bits
on 32-bit architectures and 64 bits on 64-bit architectures.

The CRC values generated by genksyms represent the compatibility of
exported symbols. Therefore, reproducibility is important. In other
words, we need to ensure that the output is the same when the kernel
source is identical, regardless of whether genksyms is running on a
32-bit or 64-bit build machine.

Fortunately, the output from genksyms is not affected by the build
machine's architecture because only the lower 32 bits of the
'unsigned long' variables are used.

To make it even clearer that the CRC calculation is independent of
the build machine's architecture, this commit explicitly uses the
fixed-width type, uint32_t.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This commit is contained in:
Masahiro Yamada 2025-01-03 16:30:43 +09:00
parent 2759bd908f
commit a56fece7f3
1 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
scripts/genksyms/genksyms.c
View File

@ -12,6 +12,7 @@
#include <stdio.h> #include <stdio.h>
#include <string.h> #include <string.h>
#include <stdint.h>
#include <stdlib.h> #include <stdlib.h>
#include <unistd.h> #include <unistd.h>
#include <assert.h> #include <assert.h>
@ -60,7 +61,7 @@ static void print_type_name(enum symbol_type type, const char *name);
/*----------------------------------------------------------------------*/ /*----------------------------------------------------------------------*/
static const unsigned int crctab32[] = { static const uint32_t crctab32[] = {
0x00000000U, 0x77073096U, 0xee0e612cU, 0x990951baU, 0x076dc419U, 0x00000000U, 0x77073096U, 0xee0e612cU, 0x990951baU, 0x076dc419U,
0x706af48fU, 0xe963a535U, 0x9e6495a3U, 0x0edb8832U, 0x79dcb8a4U, 0x706af48fU, 0xe963a535U, 0x9e6495a3U, 0x0edb8832U, 0x79dcb8a4U,
0xe0d5e91eU, 0x97d2d988U, 0x09b64c2bU, 0x7eb17cbdU, 0xe7b82d07U, 0xe0d5e91eU, 0x97d2d988U, 0x09b64c2bU, 0x7eb17cbdU, 0xe7b82d07U,
@ -115,19 +116,19 @@ static const unsigned int crctab32[] = {
0x2d02ef8dU 0x2d02ef8dU
}; };
static unsigned long partial_crc32_one(unsigned char c, unsigned long crc) static uint32_t partial_crc32_one(uint8_t c, uint32_t crc)
{ {
return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8); return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
} }
static unsigned long partial_crc32(const char *s, unsigned long crc) static uint32_t partial_crc32(const char *s, uint32_t crc)
{ {
while (*s) while (*s)
crc = partial_crc32_one(*s++, crc); crc = partial_crc32_one(*s++, crc);
return crc; return crc;
} }
static unsigned long crc32(const char *s) static uint32_t crc32(const char *s)
{ {
return partial_crc32(s, 0xffffffff) ^ 0xffffffff; return partial_crc32(s, 0xffffffff) ^ 0xffffffff;
} }
@ -517,7 +518,7 @@ static void print_list(FILE * f, struct string_list *list)
} }
} }
static unsigned long expand_and_crc_sym(struct symbol *sym, unsigned long crc) static uint32_t expand_and_crc_sym(struct symbol *sym, uint32_t crc)
{ {
struct string_list *list = sym->defn; struct string_list *list = sym->defn;
struct string_list **e, **b; struct string_list **e, **b;
@ -624,7 +625,7 @@ static unsigned long expand_and_crc_sym(struct symbol *sym, unsigned long crc)
void export_symbol(const char *name) void export_symbol(const char *name)
{ {
struct symbol *sym; struct symbol *sym;
unsigned long crc; uint32_t crc;
int has_changed = 0; int has_changed = 0;
sym = find_symbol(name, SYM_NORMAL, 0); sym = find_symbol(name, SYM_NORMAL, 0);
@ -672,7 +673,7 @@ void export_symbol(const char *name)
if (flag_dump_defs) if (flag_dump_defs)
fputs(">\n", debugfile); fputs(">\n", debugfile);
printf("#SYMVER %s 0x%08lx\n", name, crc); printf("#SYMVER %s 0x%08lx\n", name, (unsigned long)crc);
} }
/*----------------------------------------------------------------------*/ /*----------------------------------------------------------------------*/