Skip to content

Commit 409c8fb

Browse files
guoren83palmer-dabbelt
authored andcommitted
riscv: ftrace: Remove wasted nops for !RISCV_ISA_C
When CONFIG_RISCV_ISA_C=n, -fpatchable-function-entry=8 would generate more nops than we expect. Because it treat nop opcode as 0x00000013 instead of 0x0001. Dump of assembler code for function dw_pcie_free_msi: 0xffffffff806fce94 <+0>: sd ra,-8(sp) 0xffffffff806fce98 <+4>: auipc ra,0xff90f 0xffffffff806fce9c <+8>: jalr -684(ra) # 0xffffffff8000bbec <ftrace_caller> 0xffffffff806fcea0 <+12>: ld ra,-8(sp) 0xffffffff806fcea4 <+16>: nop /* wasted */ 0xffffffff806fcea8 <+20>: nop /* wasted */ 0xffffffff806fceac <+24>: nop /* wasted */ 0xffffffff806fceb0 <+28>: nop /* wasted */ 0xffffffff806fceb4 <+0>: addi sp,sp,-48 0xffffffff806fceb8 <+4>: sd s0,32(sp) 0xffffffff806fcebc <+8>: sd s1,24(sp) 0xffffffff806fcec0 <+12>: sd s2,16(sp) 0xffffffff806fcec4 <+16>: sd s3,8(sp) 0xffffffff806fcec8 <+20>: sd ra,40(sp) 0xffffffff806fcecc <+24>: addi s0,sp,48 Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Signed-off-by: Guo Ren <guoren@kernel.org> Link: https://lore.kernel.org/r/20230112090603.1295340-3-guoren@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
1 parent 8547649 commit 409c8fb

File tree

1 file changed

+4
-0
lines changed

1 file changed

+4
-0
lines changed

arch/riscv/Makefile

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,11 @@ LDFLAGS_vmlinux :=
1111
ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
1212
LDFLAGS_vmlinux := --no-relax
1313
KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
14+
ifeq ($(CONFIG_RISCV_ISA_C),y)
1415
CC_FLAGS_FTRACE := -fpatchable-function-entry=8
16+
else
17+
CC_FLAGS_FTRACE := -fpatchable-function-entry=4
18+
endif
1519
endif
1620

1721
ifeq ($(CONFIG_CMODEL_MEDLOW),y)

0 commit comments

Comments
 (0)