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authorMasahiro Yamada <masahiroy@kernel.org>2023-06-01 15:09:56 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2023-06-02 11:59:52 +0300
commit56a24b8ce6a7f9c4a21b2276a8644f6f3d8fc14d (patch)
treef9fd7835f780161076444c77a4c1c6524232a079 /scripts/mod
parentb7c63520f6703a25eebb4f8138fed764fcae1c6f (diff)
downloadlinux-56a24b8ce6a7f9c4a21b2276a8644f6f3d8fc14d.tar.xz
modpost: fix section mismatch message for R_ARM_{PC24,CALL,JUMP24}
addend_arm_rel() processes R_ARM_PC24, R_ARM_CALL, R_ARM_JUMP24 in a wrong way. Here, test code. [test code for R_ARM_JUMP24] .section .init.text,"ax" bar: bx lr .section .text,"ax" .globl foo foo: b bar [test code for R_ARM_CALL] .section .init.text,"ax" bar: bx lr .section .text,"ax" .globl foo foo: push {lr} bl bar pop {pc} If you compile it with ARM multi_v7_defconfig, modpost will show the symbol name, (unknown). WARNING: modpost: vmlinux.o: section mismatch in reference: foo (section: .text) -> (unknown) (section: .init.text) (You need to use GNU linker instead of LLD to reproduce it.) Fix the code to make modpost show the correct symbol name. I imported (with adjustment) sign_extend32() from include/linux/bitops.h. The '+8' is the compensation for pc-relative instruction. It is documented in "ELF for the Arm Architecture" [1]. "If the relocation is pc-relative then compensation for the PC bias (the PC value is 8 bytes ahead of the executing instruction in Arm state and 4 bytes in Thumb state) must be encoded in the relocation by the object producer." [1]: https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm") Fixes: 6e2e340b59d2 ("ARM: 7324/1: modpost: Fix section warnings for ARM for many compilers") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'scripts/mod')
-rw-r--r--scripts/mod/modpost.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index c68dad45ace2..e47bba7cfad2 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1277,12 +1277,20 @@ static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
#define R_ARM_THM_JUMP19 51
#endif
+static int32_t sign_extend32(int32_t value, int index)
+{
+ uint8_t shift = 31 - index;
+
+ return (int32_t)(value << shift) >> shift;
+}
+
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);
void *loc = reloc_location(elf, sechdr, r);
uint32_t inst;
+ int32_t offset;
switch (r_typ) {
case R_ARM_ABS32:
@@ -1292,6 +1300,10 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
+ inst = TO_NATIVE(*(uint32_t *)loc);
+ offset = sign_extend32((inst & 0x00ffffff) << 2, 25);
+ r->r_addend = offset + sym->st_value + 8;
+ break;
case R_ARM_THM_CALL:
case R_ARM_THM_JUMP24:
case R_ARM_THM_JUMP19: