From 16badacd8af48980c546839626d0329bab32b4c3 Mon Sep 17 00:00:00 2001 From: Alexandre Ghiti Date: Fri, 22 Mar 2024 12:26:29 +0100 Subject: [PATCH] riscv: Improve sbi_ecall() code generation by reordering arguments The sbi_ecall() function arguments are not in the same order as the ecall arguments, so we end up re-ordering the registers before the ecall which is useless and costly. So simply reorder the arguments in the same way as expected by ecall. Instead of reordering directly the arguments of sbi_ecall(), use a proxy macro since the current ordering is more natural. Before: Dump of assembler code for function sbi_ecall: 0xffffffff800085e0 <+0>: add sp,sp,-32 0xffffffff800085e2 <+2>: sd s0,24(sp) 0xffffffff800085e4 <+4>: mv t1,a0 0xffffffff800085e6 <+6>: add s0,sp,32 0xffffffff800085e8 <+8>: mv t3,a1 0xffffffff800085ea <+10>: mv a0,a2 0xffffffff800085ec <+12>: mv a1,a3 0xffffffff800085ee <+14>: mv a2,a4 0xffffffff800085f0 <+16>: mv a3,a5 0xffffffff800085f2 <+18>: mv a4,a6 0xffffffff800085f4 <+20>: mv a5,a7 0xffffffff800085f6 <+22>: mv a6,t3 0xffffffff800085f8 <+24>: mv a7,t1 0xffffffff800085fa <+26>: ecall 0xffffffff800085fe <+30>: ld s0,24(sp) 0xffffffff80008600 <+32>: add sp,sp,32 0xffffffff80008602 <+34>: ret After: Dump of assembler code for function __sbi_ecall: 0xffffffff8000b6b2 <+0>: add sp,sp,-32 0xffffffff8000b6b4 <+2>: sd s0,24(sp) 0xffffffff8000b6b6 <+4>: add s0,sp,32 0xffffffff8000b6b8 <+6>: ecall 0xffffffff8000b6bc <+10>: ld s0,24(sp) 0xffffffff8000b6be <+12>: add sp,sp,32 0xffffffff8000b6c0 <+14>: ret Signed-off-by: Alexandre Ghiti Reviewed-by: Atish Patra Reviewed-by: Yunhui Cui Link: https://lore.kernel.org/r/20240322112629.68170-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/sbi.h | 10 ++++++---- arch/riscv/kernel/sbi.c | 10 +++++----- 2 files changed, 11 insertions(+), 9 deletions(-) diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h index 1079e214fe855..7cffd4ffecd0c 100644 --- a/arch/riscv/include/asm/sbi.h +++ b/arch/riscv/include/asm/sbi.h @@ -304,10 +304,12 @@ struct sbiret { }; void sbi_init(void); -struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0, - unsigned long arg1, unsigned long arg2, - unsigned long arg3, unsigned long arg4, - unsigned long arg5); +struct sbiret __sbi_ecall(unsigned long arg0, unsigned long arg1, + unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5, + int fid, int ext); +#define sbi_ecall(e, f, a0, a1, a2, a3, a4, a5) \ + __sbi_ecall(a0, a1, a2, a3, a4, a5, f, e) #ifdef CONFIG_RISCV_SBI_V01 void sbi_console_putchar(int ch); diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index a1d21d8f52936..837bdab2601bd 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -27,10 +27,10 @@ static int (*__sbi_rfence)(int fid, const struct cpumask *cpu_mask, unsigned long start, unsigned long size, unsigned long arg4, unsigned long arg5) __ro_after_init; -struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0, - unsigned long arg1, unsigned long arg2, - unsigned long arg3, unsigned long arg4, - unsigned long arg5) +struct sbiret __sbi_ecall(unsigned long arg0, unsigned long arg1, + unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5, + int fid, int ext) { struct sbiret ret; @@ -55,7 +55,7 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0, return ret; } -EXPORT_SYMBOL(sbi_ecall); +EXPORT_SYMBOL(__sbi_ecall); int sbi_err_map_linux_errno(int err) {