The initial aim is to silence the following objtool warnings:
arch/loongarch/kernel/fpu.o: warning: objtool: _save_fp_context() falls through to next function fault()
arch/loongarch/kernel/fpu.o: warning: objtool: _restore_fp_context() falls through to next function fault()
arch/loongarch/kernel/fpu.o: warning: objtool: _save_lsx_context() falls through to next function fault()
arch/loongarch/kernel/fpu.o: warning: objtool: _restore_lsx_context() falls through to next function fault()
arch/loongarch/kernel/fpu.o: warning: objtool: _save_lasx_context() falls through to next function fault()
arch/loongarch/kernel/fpu.o: warning: objtool: _restore_lasx_context() falls through to next function fault()
Currently, SYM_FUNC_END() defines the symbol fault as SYM_T_FUNC which
is STT_FUNC, the objtool warnings are generated through the following
code:
tools/objtool/include/objtool/check.h
static inline struct symbol *insn_func(struct instruction *insn)
{
struct symbol *sym = insn->sym;
if (sym && sym->type != STT_FUNC)
sym = NULL;
return sym;
}
tools/objtool/check.c
static int validate_branch(struct objtool_file *file, struct symbol *func,
struct instruction *insn, struct insn_state state)
{
...
if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
...
WARN("%s() falls through to next function %s()",
func->name, insn_func(insn)->name);
return 1;
}
...
}
We can see that the fixup can be a local label in the following code:
arch/loongarch/include/asm/asm-extable.h
.pushsection __ex_table, "a"; \
.balign 4; \
.long ((insn) - .); \
.long ((fixup) - .); \
.short (type); \
.short (data); \
.popsection;
.macro _asm_extable, insn, fixup
__ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_FIXUP, 0)
.endm
Like arch/loongarch/lib/*.S, just define the symbol fault as a local
label in fpu.S.
Before:
$ readelf -s arch/loongarch/kernel/fpu.o | awk -F: /fault/'{print $2}'
000000000000053c 8 FUNC GLOBAL DEFAULT 1 fault
After:
$ readelf -s arch/loongarch/kernel/fpu.o | awk -F: /fault/'{print $2}'
000000000000053c 0 NOTYPE LOCAL DEFAULT 1 .L_fixup_fpu_fault
Co-developed-by: Youling Tang <[email protected]>
Signed-off-by: Youling Tang <[email protected]>
Signed-off-by: Tiezhu Yang <[email protected]>
---
There is a same issue in lbt.S, Huacai suggested to squash the changes
in the original patch:
"LoongArch: Add Loongson Binary Translation (LBT) extension support"
arch/loongarch/kernel/fpu.S | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/loongarch/kernel/fpu.S b/arch/loongarch/kernel/fpu.S
index b4032de..3177725 100644
--- a/arch/loongarch/kernel/fpu.S
+++ b/arch/loongarch/kernel/fpu.S
@@ -22,7 +22,7 @@
.macro EX insn, reg, src, offs
.ex\@: \insn \reg, \src, \offs
- _asm_extable .ex\@, fault
+ _asm_extable .ex\@, .L_fixup_fpu_fault
.endm
.macro sc_save_fp base
@@ -521,7 +521,6 @@ SYM_FUNC_START(_restore_lasx_context)
jr ra
SYM_FUNC_END(_restore_lasx_context)
-SYM_FUNC_START(fault)
+.L_fixup_fpu_fault:
li.w a0, -EFAULT # failure
jr ra
-SYM_FUNC_END(fault)
--
2.1.0