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riscv: jump_label: mark arguments as const to satisfy asm constraints

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Samuel reported that the static branch usage in cpu_relax() breaks
building with CONFIG_CC_OPTIMIZE_FOR_SIZE:

In file included from <command-line>:
./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax':
././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0
probably does not match constraints
  285 | #define asm_volatile_goto(x...) asm goto(x)
      |                                 ^~~
./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
'asm_volatile_goto'
   41 |         asm_volatile_goto(
      |         ^~~~~~~~~~~~~~~~~
././include/linux/compiler_types.h:285:33: error: impossible constraint
in 'asm'
  285 | #define asm_volatile_goto(x...) asm goto(x)
      |                                 ^~~
./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro
'asm_volatile_goto'
   41 |         asm_volatile_goto(
      |         ^~~~~~~~~~~~~~~~~
make[1]: *** [scripts/Makefile.build:249:
arch/riscv/kernel/vdso/vgettimeofday.o] Error 1
make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2

Maybe "-Os" prevents GCC from detecting that the key/branch arguments
can be treated as constants and used as immediate operands. Inspired
by x86's commit 864b435514b2("x86/jump_label: Mark arguments as const to
satisfy asm constraints"), and as pointed out by Steven: "The "i"
constraint needs to be a constant.", let's do similar modifications to
riscv.

Tested by CC_OPTIMIZE_FOR_SIZE + gcc and CC_OPTIMIZE_FOR_SIZE + clang.

Link: https://lore.kernel.org/linux-riscv/20220922060958.44203-1-samuel@sholland.org/
Link: https://lore.kernel.org/all/20210212094059.5f8d05e8@gandalf.local.home/
Fixes: 8eb060e101 ("arch/riscv: add Zihintpause support")
Reported-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20221008145437.491-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Jisheng Zhang 2022-10-08 22:54:37 +08:00 committed by Palmer Dabbelt
parent 9abf2313ad
commit 89fd4a1df8
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
1 changed files with 4 additions and 4 deletions
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8
arch/riscv/include/asm/jump_label.h
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@ -14,8 +14,8 @@
#define JUMP_LABEL_NOP_SIZE 4
static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
static __always_inline bool arch_static_branch(struct static_key * const key,
const bool branch)
{
asm_volatile_goto(
" .option push \n\t"
@ -35,8 +35,8 @@ label:
return true;
}
static __always_inline bool arch_static_branch_jump(struct static_key *key,
bool branch)
static __always_inline bool arch_static_branch_jump(struct static_key * const key,
const bool branch)
{
asm_volatile_goto(
" .option push \n\t"