From 6fef411be1f57db80384a6166e60335e59feeebd Mon Sep 17 00:00:00 2001 From: Heiko Stuebner Date: Tue, 4 Oct 2022 21:18:54 +0200 Subject: [PATCH 1/2] RISC-V: Cache SBI vendor values sbi_get_mvendorid(), sbi_get_marchid() and sbi_get_mimpid() might get called multiple times, though the values of these CSRs should not change during the runtime of a specific machine. So cache the values in the functions and prevent multiple ecalls to read these values. Suggested-by: Atish Patra Signed-off-by: Heiko Stuebner --- arch/riscv/kernel/sbi.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index 775d3322b422..5be8f90f325e 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -625,17 +625,32 @@ static inline long sbi_get_firmware_version(void) long sbi_get_mvendorid(void) { - return __sbi_base_ecall(SBI_EXT_BASE_GET_MVENDORID); + static long id = -1; + + if (id < 0) + id = __sbi_base_ecall(SBI_EXT_BASE_GET_MVENDORID); + + return id; } long sbi_get_marchid(void) { - return __sbi_base_ecall(SBI_EXT_BASE_GET_MARCHID); + static long id = -1; + + if (id < 0) + id = __sbi_base_ecall(SBI_EXT_BASE_GET_MARCHID); + + return id; } long sbi_get_mimpid(void) { - return __sbi_base_ecall(SBI_EXT_BASE_GET_MIMPID); + static long id = -1; + + if (id < 0) + id = __sbi_base_ecall(SBI_EXT_BASE_GET_MIMPID); + + return id; } static void sbi_send_cpumask_ipi(const struct cpumask *target) -- 2.35.1