Unverified Commit 3bd7743f authored by Jamie Iles's avatar Jamie Iles Committed by Palmer Dabbelt
Browse files

RISC-V: reduce mcount save space on RV32 



For RV32 we can reduce the size of the ABI save+restore state by using
SZREG so that register stores are packed rather than on an 8 byte
boundary.

Signed-off-by: default avatarJamie Iles <jamie@jamieiles.com>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20221115200832.706370-3-jamie@jamieiles.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 8a6841c4

arch/riscv/kernel/mcount.S

+16 −16
Original line number Diff line number Diff line
@@ -15,8 +15,8 @@ 


	.macro SAVE_ABI_STATE

	addi	sp, sp, -16

	REG_S	s0, 0(sp)

	REG_S	ra, 8(sp)

	REG_S	s0, 0*SZREG(sp)

	REG_S	ra, 1*SZREG(sp)

	addi	s0, sp, 16

	.endm
@@ -25,24 +25,24 @@ 
	 * register if a0 was not saved.

	 */

	.macro SAVE_RET_ABI_STATE

	addi	sp, sp, -32

	REG_S	s0, 16(sp)

	REG_S	ra, 24(sp)

	REG_S	a0, 8(sp)

	addi	s0, sp, 32

	addi	sp, sp, -4*SZREG

	REG_S	s0, 2*SZREG(sp)

	REG_S	ra, 3*SZREG(sp)

	REG_S	a0, 1*SZREG(sp)

	addi	s0, sp, 4*SZREG

	.endm



	.macro RESTORE_ABI_STATE

	REG_L	ra, 8(sp)

	REG_L	s0, 0(sp)

	REG_L	ra, 1*SZREG(sp)

	REG_L	s0, 0*SZREG(sp)

	addi	sp, sp, 16

	.endm



	.macro RESTORE_RET_ABI_STATE

	REG_L	ra, 24(sp)

	REG_L	s0, 16(sp)

	REG_L	a0, 8(sp)

	addi	sp, sp, 32

	REG_L	ra, 3*SZREG(sp)

	REG_L	s0, 2*SZREG(sp)

	REG_L	a0, 1*SZREG(sp)

	addi	sp, sp, 4*SZREG

	.endm



ENTRY(ftrace_stub)
@@ -101,10 +101,10 @@ ENTRY(MCOUNT_NAME) 
 * prepare_to_return(&ra_to_caller_of_caller, ra_to_caller)

 */

do_ftrace_graph_caller:

	addi	a0, s0, -8

	addi	a0, s0, -SZREG

	mv	a1, ra

#ifdef HAVE_FUNCTION_GRAPH_FP_TEST

	REG_L	a2, -16(s0)

	REG_L	a2, -2*SZREG(s0)

#endif

	SAVE_ABI_STATE

	call	prepare_ftrace_return
@@ -117,7 +117,7 @@ do_ftrace_graph_caller: 
 * (*ftrace_trace_function)(ra_to_caller, ra_to_caller_of_caller)

 */

do_trace:

	REG_L	a1, -8(s0)

	REG_L	a1, -SZREG(s0)

	mv	a0, ra



	SAVE_ABI_STATE