6.14-stable review patch. If anyone has any objections, please let me know.
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From: Tiezhu Yang yangtiezhu@loongson.cn
[ Upstream commit c4b93b06230ae49870187189d9f7342f6ad4f14e ]
For the most part, an absolute relocation type is used for rodata. In the case of STT_SECTION, reloc->sym->offset is always zero, for the other symbol types, reloc_addend(reloc) is always zero, thus it can use a simple statement "reloc->sym->offset + reloc_addend(reloc)" to obtain the symbol offset for various symbol types.
When compiling on LoongArch, there exist PC relative relocation types for rodata, it needs to calculate the symbol offset with "S + A - PC" according to the spec of "ELF for the LoongArch Architecture".
If there is only one jump table in the rodata, the "PC" is the entry address which is equal with the value of reloc_offset(reloc), at this time, reloc_offset(table) is 0.
If there are many jump tables in the rodata, the "PC" is the offset of the jump table's base address which is equal with the value of reloc_offset(reloc) - reloc_offset(table).
So for LoongArch, if the relocation type is PC relative, it can use a statement "reloc_offset(reloc) - reloc_offset(table)" to get the "PC" value when calculating the symbol offset with "S + A - PC" for one or many jump tables in the rodata.
Add an arch-specific function arch_jump_table_sym_offset() to assign the symbol offset, for the most part that is an absolute relocation, the default value is "reloc->sym->offset + reloc_addend(reloc)" in the weak definition, it can be overridden by each architecture that has different requirements.
Link: https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn Link: https://lore.kernel.org/r/20250211115016.26913-4-yangtiezhu@loongson.cn Acked-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Stable-dep-of: ef753d66051c ("objtool: Fix detection of consecutive jump tables on Clang 20") Signed-off-by: Sasha Levin sashal@kernel.org --- tools/objtool/arch/loongarch/decode.c | 17 +++++++++++++---- tools/objtool/arch/loongarch/include/arch/elf.h | 7 +++++++ tools/objtool/check.c | 7 ++++++- tools/objtool/include/objtool/arch.h | 1 + 4 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c index b64205b89f6b4..02e4905559667 100644 --- a/tools/objtool/arch/loongarch/decode.c +++ b/tools/objtool/arch/loongarch/decode.c @@ -5,10 +5,7 @@ #include <asm/inst.h> #include <asm/orc_types.h> #include <linux/objtool_types.h> - -#ifndef EM_LOONGARCH -#define EM_LOONGARCH 258 -#endif +#include <arch/elf.h>
int arch_ftrace_match(char *name) { @@ -374,3 +371,15 @@ unsigned int arch_reloc_size(struct reloc *reloc) return 8; } } + +unsigned long arch_jump_table_sym_offset(struct reloc *reloc, struct reloc *table) +{ + switch (reloc_type(reloc)) { + case R_LARCH_32_PCREL: + case R_LARCH_64_PCREL: + return reloc->sym->offset + reloc_addend(reloc) - + (reloc_offset(reloc) - reloc_offset(table)); + default: + return reloc->sym->offset + reloc_addend(reloc); + } +} diff --git a/tools/objtool/arch/loongarch/include/arch/elf.h b/tools/objtool/arch/loongarch/include/arch/elf.h index 9623d663220ef..ec79062c9554d 100644 --- a/tools/objtool/arch/loongarch/include/arch/elf.h +++ b/tools/objtool/arch/loongarch/include/arch/elf.h @@ -18,6 +18,13 @@ #ifndef R_LARCH_32_PCREL #define R_LARCH_32_PCREL 99 #endif +#ifndef R_LARCH_64_PCREL +#define R_LARCH_64_PCREL 109 +#endif + +#ifndef EM_LOONGARCH +#define EM_LOONGARCH 258 +#endif
#define R_NONE R_LARCH_NONE #define R_ABS32 R_LARCH_32 diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 4b9f01a11792f..12bf6c1f5071d 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1944,6 +1944,11 @@ static int add_special_section_alts(struct objtool_file *file) return ret; }
+__weak unsigned long arch_jump_table_sym_offset(struct reloc *reloc, struct reloc *table) +{ + return reloc->sym->offset + reloc_addend(reloc); +} + static int add_jump_table(struct objtool_file *file, struct instruction *insn, struct reloc *next_table) { @@ -1972,7 +1977,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn, if (prev_offset && reloc_offset(reloc) != prev_offset + arch_reloc_size(reloc)) break;
- sym_offset = reloc->sym->offset + reloc_addend(reloc); + sym_offset = arch_jump_table_sym_offset(reloc, table);
/* Detect function pointers from contiguous objects: */ if (reloc->sym->sec == pfunc->sec && sym_offset == pfunc->offset) diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h index 396f7c6c81c0f..089a1acc48a8d 100644 --- a/tools/objtool/include/objtool/arch.h +++ b/tools/objtool/include/objtool/arch.h @@ -98,5 +98,6 @@ int arch_rewrite_retpolines(struct objtool_file *file); bool arch_pc_relative_reloc(struct reloc *reloc);
unsigned int arch_reloc_size(struct reloc *reloc); +unsigned long arch_jump_table_sym_offset(struct reloc *reloc, struct reloc *table);
#endif /* _ARCH_H */