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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_START()/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_fpu_fault
Co-developed-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.