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modpost: Ignore relaxation and alignment marker relocs on LoongArch

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With recent trunk versions of binutils and gcc, alignment directives are
represented with R_LARCH_ALIGN relocs on LoongArch, which is necessary
for the linker to maintain alignment requirements during its relaxation
passes. And even though the kernel is built with relaxation disabled, so
far a small number of R_LARCH_RELAX marker relocs are still emitted as
part of la.* pseudo instructions in assembly. These two kinds of relocs
do not refer to symbols, which can trip up modpost's section mismatch
checks, because the r_offset of said relocs can be zero or any other
meaningless value, eventually leading to a `from == NULL` condition in
default_mismatch_handler and SIGSEGV.

As the two kinds of relocs are not concerned with symbols, just ignore
them for section mismatch check purposes.

Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
WANG Xuerui 2024-01-17 12:42:59 +08:00 committed by Huacai Chen
parent 0dd3ee3112
commit 2772ae4d66
1 changed files with 17 additions and 2 deletions
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19
scripts/mod/modpost.c
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@ -1346,6 +1346,14 @@ static Elf_Addr addend_mips_rel(uint32_t *location, unsigned int r_type)
#define R_LARCH_SUB32 55
#endif
#ifndef R_LARCH_RELAX
#define R_LARCH_RELAX 100
#endif
#ifndef R_LARCH_ALIGN
#define R_LARCH_ALIGN 102
#endif
static void get_rel_type_and_sym(struct elf_info *elf, uint64_t r_info,
unsigned int *r_type, unsigned int *r_sym)
{
@ -1400,9 +1408,16 @@ static void section_rela(struct module *mod, struct elf_info *elf,
continue;
break;
case EM_LOONGARCH:
if (!strcmp("__ex_table", fromsec) &&
r_type == R_LARCH_SUB32)
switch (r_type) {
case R_LARCH_SUB32:
if (!strcmp("__ex_table", fromsec))
continue;
break;
case R_LARCH_RELAX:
case R_LARCH_ALIGN:
/* These relocs do not refer to symbols */
continue;
}
break;
}