From 76169cd214e4830a523c8c2ee7bbddc04b4253df Mon Sep 17 00:00:00 2001 From: Miquel Sabaté Solà Date: Thu, 5 Dec 2024 15:34:33 +0100 Subject: supervisor: Add an example on the HSM extension MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The HSM extension from SBI v2.0 allows a supervisor to manage the state of harts on the system. Moreover, it also guarantees that only one hart makes it into the booting stages of the supervisor, and it's up to the supervisor to wake up the rest through the HSM extension. I have added an example which showcases this extension in different ways, and it finally shuts down the machine. Signed-off-by: Miquel Sabaté Solà --- arch/riscv/supervisor/hsm/sbi.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 arch/riscv/supervisor/hsm/sbi.c (limited to 'arch/riscv/supervisor/hsm/sbi.c') diff --git a/arch/riscv/supervisor/hsm/sbi.c b/arch/riscv/supervisor/hsm/sbi.c new file mode 100644 index 0000000..72c1521 --- /dev/null +++ b/arch/riscv/supervisor/hsm/sbi.c @@ -0,0 +1,29 @@ +#include "compiler.h" +#include "sbi.h" + +// Implementation taken from the Linux kernel (6.12). +struct sbi_ret __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 sbi_ret ret; + + register uintptr_t a0 asm("a0") = (uintptr_t)(arg0); + register uintptr_t a1 asm("a1") = (uintptr_t)(arg1); + register uintptr_t a2 asm("a2") = (uintptr_t)(arg2); + register uintptr_t a3 asm("a3") = (uintptr_t)(arg3); + register uintptr_t a4 asm("a4") = (uintptr_t)(arg4); + register uintptr_t a5 asm("a5") = (uintptr_t)(arg5); + register uintptr_t a6 asm("a6") = (uintptr_t)(fid); + register uintptr_t a7 asm("a7") = (uintptr_t)(ext); + + asm volatile("ecall" + : "+r"(a0), "+r"(a1) + : "r"(a2), "r"(a3), "r"(a4), "r"(a5), "r"(a6), "r"(a7) + : "memory"); + + ret.error = (long)a0; + ret.value = (long)a1; + + return ret; +} -- cgit v1.2.3