For ARM defconfig (i.e. multi_v7_defconfig), modpost fails to detect
some types of section mismatches.
[test code]
#include <linux/init.h>
int __initdata foo;
int get_foo(void) { return foo; }
It is apparently a bad reference, but modpost does not report anything.
The test code above produces the following relocations.
Relocation section '.rel.text' at offset 0x200 contains 2 entries:
Offset Info Type Sym.Value Sym. Name
00000000 0000062b R_ARM_MOVW_ABS_NC 00000000 .LANCHOR0
00000004 0000062c R_ARM_MOVT_ABS 00000000 .LANCHOR0
Currently, R_ARM_MOVW_ABS_NC and R_ARM_MOVT_ABS are just skipped.
Add code to handle them. I checked arch/arm/kernel/module.c to learn
how the offset is encoded in the instruction.
The referenced symbol in relocation might be a local anchor.
If is_valid_name() returns false, let's search for a better symbol name.
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
scripts/mod/modpost.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index e47bba7cfad2..5a5e802b160c 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1078,7 +1078,7 @@ static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
/**
* Find symbol based on relocation record info.
* In some cases the symbol supplied is a valid symbol so
- * return refsym. If st_name != 0 we assume this is a valid symbol.
+ * return refsym. If is_valid_name() == true, we assume this is a valid symbol.
* In other cases the symbol needs to be looked up in the symbol table
* based on section and address.
* **/
@@ -1091,7 +1091,7 @@ static Elf_Sym *find_tosym(struct elf_info *elf, Elf64_Sword addr,
Elf64_Sword d;
unsigned int relsym_secindex;
- if (relsym->st_name != 0)
+ if (is_valid_name(elf, relsym))
return relsym;
/*
@@ -1297,6 +1297,13 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
inst = TO_NATIVE(*(uint32_t *)loc);
r->r_addend = inst + sym->st_value;
break;
+ case R_ARM_MOVW_ABS_NC:
+ case R_ARM_MOVT_ABS:
+ inst = TO_NATIVE(*(uint32_t *)loc);
+ offset = sign_extend32(((inst & 0xf0000) >> 4) | (inst & 0xfff),
+ 15);
+ r->r_addend = offset + sym->st_value;
+ break;
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
--
2.39.2
