From: ShihPo Hung Date: Tue, 14 Jan 2020 22:17:31 -0800 Subject: [PATCH] target/riscv: Fix tb->flags FS status It was found that running libquantum on riscv-linux qemu produced an incorrect result. After investigation, FP registers are not saved during context switch due to incorrect mstatus.FS. In current implementation tb->flags merges all non-disabled state to dirty. This means the code in mark_fs_dirty in translate.c that handles initial and clean states is unreachable. This patch fixes it and is successfully tested with: libquantum Thanks to Richard for pointing out the actual bug. v3: remove the redundant condition v2: root cause FS problem Suggested-by: Richard Henderson Signed-off-by: ShihPo Hung Reviewed-by: Richard Henderson Signed-off-by: Palmer Dabbelt --- target/riscv/cpu.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index e59343e13c..de0a8d893a 100644 --- a/target/riscv/cpu.h +++ b/target/riscv/cpu.h @@ -293,10 +293,7 @@ static inline void cpu_get_tb_cpu_state(CPURISCVState *env, target_ulong *pc, #ifdef CONFIG_USER_ONLY *flags = TB_FLAGS_MSTATUS_FS; #else - *flags = cpu_mmu_index(env, 0); - if (riscv_cpu_fp_enabled(env)) { - *flags |= TB_FLAGS_MSTATUS_FS; - } + *flags = cpu_mmu_index(env, 0) | (env->mstatus & MSTATUS_FS); #endif }