From f1cb0951c5298753652a73cfd8efc0b1a82f37de Mon Sep 17 00:00:00 2001 From: Nathan Froyd Date: Thu, 7 Jun 2012 15:04:14 +0000 Subject: [PATCH] MIPS: Correct FCR0 initialization This change addresses a problem where QEMU incorrectly traps on floating-point MADD group instructions with SIGILL, at least while emulating MIPS32r2 processors. These instructions use the COP1X major opcode and include ones like: madd.d $f2,$f4,$f2,$f6 Here's Nathan's original analysis of the problem: "QEMU essentially does: d = find_cpu (cpu_string) // get CPU definition fpu_init (env, d) // initialize fpu state (init FCR0, basically) cpu_reset (env) ...and the cpu_reset call clears all interesting state that fpu_init setup, then proceeds to reinitialize all the CP0 registers...but not FCR0." I have verified this change with system emulation running the GDB test suite for the mips-sde-elf target (o32, big endian, 24Kf CPU emulated), there were 55 progressions and no regressions. Signed-off-by: Maciej W. Rozycki Reviewed-by: Richard Henderson Signed-off-by: Blue Swirl --- target-mips/translate.c | 1 + 1 file changed, 1 insertion(+) diff --git a/target-mips/translate.c b/target-mips/translate.c index 4e15ee3..47daf85 100644 --- a/target-mips/translate.c +++ b/target-mips/translate.c @@ -12763,6 +12763,7 @@ void cpu_state_reset(CPUMIPSState *env) env->CP0_SRSConf3 = env->cpu_model->CP0_SRSConf3; env->CP0_SRSConf4_rw_bitmask = env->cpu_model->CP0_SRSConf4_rw_bitmask; env->CP0_SRSConf4 = env->cpu_model->CP0_SRSConf4; + env->active_fpu.fcr0 = env->cpu_model->CP1_fcr0; env->insn_flags = env->cpu_model->insn_flags; #if defined(CONFIG_USER_ONLY) -- 2.7.4