Commit d107b326 authored by Petr Pavlu's avatar Petr Pavlu Committed by Josh Poimboeuf
Browse files

objtool: Replace custom macros in elf.c with shared ones 



The source file tools/objtool/elf.c defines the macros ALIGN_UP(),
ALIGN_UP_POW2() and MAX(). These macros unnecessarily duplicate
functionality already available under tools/include/, specifically ALIGN(),
roundup_pow_of_two() and max().

More importantly, the definition of ALIGN_UP_POW2() is incorrect when the
input is 1, as it results in a call to __builtin_clz(0), which produces an
undefined result. This issue impacts the function elf_alloc_reloc(). When
adding the first relocation to a section, the function allocates an
undefined number of relocations.

Replace the custom macros with the shared functionality to resolve these
issues.

Fixes: 2c05ca02 ("objtool: Add elf_create_reloc() and elf_init_reloc()")
Signed-off-by: default avatarPetr Pavlu <petr.pavlu@suse.com>
Link: https://patch.msgid.link/20260126151356.3924887-1-petr.pavlu@suse.com


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent fd4eeb30

tools/objtool/elf.c

+6 −7
Original line number Diff line number Diff line
@@ -18,15 +18,14 @@ 
#include <errno.h>

#include <libgen.h>

#include <ctype.h>

#include <linux/align.h>

#include <linux/kernel.h>

#include <linux/interval_tree_generic.h>

#include <linux/log2.h>

#include <objtool/builtin.h>

#include <objtool/elf.h>

#include <objtool/warn.h>



#define ALIGN_UP(x, align_to) (((x) + ((align_to)-1)) & ~((align_to)-1))

#define ALIGN_UP_POW2(x) (1U << ((8 * sizeof(x)) - __builtin_clz((x) - 1U)))

#define MAX(a, b) ((a) > (b) ? (a) : (b))



static inline u32 str_hash(const char *str)

{

	return jhash(str, strlen(str), 0);
@@ -1336,7 +1335,7 @@ unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char 
		return -1;

	}



	offset = ALIGN_UP(strtab->sh.sh_size, strtab->sh.sh_addralign);

	offset = ALIGN(strtab->sh.sh_size, strtab->sh.sh_addralign);



	if (!elf_add_data(elf, strtab, str, strlen(str) + 1))

		return -1;
@@ -1378,7 +1377,7 @@ void *elf_add_data(struct elf *elf, struct section *sec, const void *data, size_ 
	sec->data->d_size = size;

	sec->data->d_align = 1;



	offset = ALIGN_UP(sec->sh.sh_size, sec->sh.sh_addralign);

	offset = ALIGN(sec->sh.sh_size, sec->sh.sh_addralign);

	sec->sh.sh_size = offset + size;



	mark_sec_changed(elf, sec, true);
@@ -1502,7 +1501,7 @@ static int elf_alloc_reloc(struct elf *elf, struct section *rsec) 
	rsec->data->d_size = nr_relocs_new * elf_rela_size(elf);

	rsec->sh.sh_size   = rsec->data->d_size;



	nr_alloc = MAX(64, ALIGN_UP_POW2(nr_relocs_new));

	nr_alloc = max(64UL, roundup_pow_of_two(nr_relocs_new));

	if (nr_alloc <= rsec->nr_alloc_relocs)

		return 0;