ARM defconfig misses to detect some section mismatches.
[test code]
#include <linux/init.h>
int __initdata foo;
int get_foo(int x) { return foo; }
It is apparently a bad reference, but modpost does not report anything
for ARM defconfig (i.e. multi_v7_defconfig).
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
Relocation section '.rel.ARM.exidx' at offset 0x210 contains 2 entries:
Offset Info Type Sym.Value Sym. Name
00000000 0000022a R_ARM_PREL31 00000000 .text
00000000 00001000 R_ARM_NONE 00000000 __aeabi_unwind_cpp_pr0
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 | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 34fbbd85bfde..ed2301e951a9 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1108,7 +1108,7 @@ 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.
* **/
@@ -1121,7 +1121,7 @@ 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;
/*
@@ -1312,11 +1312,19 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
unsigned int r_typ = ELF_R_TYPE(r->r_info);
Elf_Sym *sym = elf->symtab_start + ELF_R_SYM(r->r_info);
unsigned int inst = TO_NATIVE(*reloc_location(elf, sechdr, r));
+ int offset;
switch (r_typ) {
case R_ARM_ABS32:
r->r_addend = inst + sym->st_value;
break;
+ case R_ARM_MOVW_ABS_NC:
+ case R_ARM_MOVT_ABS:
+ offset = ((inst & 0xf0000) >> 4) | (inst & 0xfff);
+ offset = (offset ^ 0x8000) - 0x8000;
+ offset += sym->st_value;
+ r->r_addend = offset;
+ break;
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
--
2.39.2
