From 68a90134c0310a1e4e707906b766c893af3cec85 Mon Sep 17 00:00:00 2001 From: Deepak Gupta Date: Wed, 5 Mar 2025 22:46:35 -0800 Subject: [PATCH] target/riscv: fix access permission checks for CSR_SSP Commit:8205bc1 ("target/riscv: introduce ssp and enabling controls for zicfiss") introduced CSR_SSP but it mis-interpreted the spec on access to CSR_SSP in M-mode. Gated to CSR_SSP is not gated via `xSSE`. But rather rules clearly specified in section "22.2.1. Shadow Stack Pointer (ssp) CSR access contr" in the priv spec. Fixes: 8205bc127a83 ("target/riscv: introduce ssp and enabling controls for zicfiss". Thanks to Adam Zabrocki for bringing this to attention. Reported-by: Adam Zabrocki Signed-off-by: Deepak Gupta Reviewed-by: Alistair Francis Message-ID: <20250306064636.452396-1-debug@rivosinc.com> Signed-off-by: Alistair Francis (cherry picked from commit 86c78b280607fcff787866a03374047c65037a90) Signed-off-by: Michael Tokarev --- target/riscv/csr.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/target/riscv/csr.c b/target/riscv/csr.c index 9846770820..c2e39c91b6 100644 --- a/target/riscv/csr.c +++ b/target/riscv/csr.c @@ -190,6 +190,11 @@ static RISCVException cfi_ss(CPURISCVState *env, int csrno) return RISCV_EXCP_ILLEGAL_INST; } + /* If ext implemented, M-mode always have access to SSP CSR */ + if (env->priv == PRV_M) { + return RISCV_EXCP_NONE; + } + /* if bcfi not active for current env, access to csr is illegal */ if (!cpu_get_bcfien(env)) { #if !defined(CONFIG_USER_ONLY) -- 2.39.5