[PATCH 3/3] modpost: continue even with unknown relocation type

From: Masahiro Yamada
Date: Tue Jun 20 2023 - 08:06:03 EST


Currently, unknown relocation types are just skipped.

The value of r_addend is only needed to get the symbol name in case
is_valid_name(elf, sym) returns false.

Even if we do not know how to calculate r_addend, we should continue.
At worst, we will get "(unknown)" as the symbol name, but it is better
than failing to detect section mismatches.

Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---

scripts/mod/modpost.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index ffe45c54f024..7e92380d4f1f 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1267,6 +1267,8 @@ static int addend_386_rel(uint32_t *location, Elf_Rela *r)
case R_386_PC32:
r->r_addend = TO_NATIVE(*location) + 4;
break;
+ default:
+ r->r_addend = (Elf_Addr)(-1);
}
return 0;
}
@@ -1382,7 +1384,7 @@ static int addend_arm_rel(void *loc, Elf_Sym *sym, Elf_Rela *r)
r->r_addend = offset + sym->st_value + 4;
break;
default:
- return 1;
+ r->r_addend = (Elf_Addr)(-1);
}
return 0;
}
@@ -1392,8 +1394,6 @@ static int addend_mips_rel(uint32_t *location, Elf_Rela *r)
unsigned int r_typ = ELF_R_TYPE(r->r_info);
uint32_t inst;

- if (r_typ == R_MIPS_HI16)
- return 1; /* skip this */
inst = TO_NATIVE(*location);
switch (r_typ) {
case R_MIPS_LO16:
@@ -1405,6 +1405,8 @@ static int addend_mips_rel(uint32_t *location, Elf_Rela *r)
case R_MIPS_32:
r->r_addend = inst;
break;
+ default:
+ r->r_addend = (Elf_Addr)(-1);
}
return 0;
}
@@ -1514,20 +1516,17 @@ static void section_rel(struct module *mod, struct elf_info *elf,
r.r_addend = 0;

loc = sym_get_data_by_offset(elf, fsecndx, r.r_offset);
- tsym = elf->symtab_start + ELF_R_SYM(r.r_info);
+ tsym = elf->symtab_start + r_sym;

switch (elf->hdr->e_machine) {
case EM_386:
- if (addend_386_rel(loc, &r))
- continue;
+ addend_386_rel(loc, &r);
break;
case EM_ARM:
- if (addend_arm_rel(loc, tsym, &r))
- continue;
+ addend_arm_rel(loc, tsym, &r);
break;
case EM_MIPS:
- if (addend_mips_rel(loc, &r))
- continue;
+ addend_mips_rel(loc, &r);
break;
default:
fatal("Please add code to calculate addend for this architecture\n");
--
2.39.2