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authorNathan Froyd <froydnj@codesourcery.com>2010-06-08 13:30:01 -0700
committerAurelien Jarno <aurelien@aurel32.net>2010-06-09 16:10:51 +0200
commitbbfa8f72e99baa0514b2b39e671830cf9a3adc44 (patch)
tree29d718f8b97573eb4b4b359e352159d696c0a19f /target-mips
parent3c824109da076d2a1df4b798f9df81b385131f92 (diff)
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target-mips: add microMIPS exception handler support
Unlike MIPS16, microMIPS lets you choose the ISA mode for your exception handlers. The ISA mode is selectable via a user-writable CP0.Config3 flag. Signed-off-by: Nathan Froyd <froydnj@codesourcery.com> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Diffstat (limited to 'target-mips')
-rw-r--r--target-mips/cpu.h1
-rw-r--r--target-mips/helper.c21
2 files changed, 16 insertions, 6 deletions
diff --git a/target-mips/cpu.h b/target-mips/cpu.h
index 7285636..c21b8e4 100644
--- a/target-mips/cpu.h
+++ b/target-mips/cpu.h
@@ -363,6 +363,7 @@ struct CPUMIPSState {
#define CP0C2_SA 0
int32_t CP0_Config3;
#define CP0C3_M 31
+#define CP0C3_ISA_ON_EXC 16
#define CP0C3_DSPP 10
#define CP0C3_LPA 7
#define CP0C3_VEIC 6
diff --git a/target-mips/helper.c b/target-mips/helper.c
index 8102f03..ea221ab 100644
--- a/target-mips/helper.c
+++ b/target-mips/helper.c
@@ -385,6 +385,18 @@ static target_ulong exception_resume_pc (CPUState *env)
return bad_pc;
}
+
+static void set_hflags_for_handler (CPUState *env)
+{
+ /* Exception handlers are entered in 32-bit mode. */
+ env->hflags &= ~(MIPS_HFLAG_M16);
+ /* ...except that microMIPS lets you choose. */
+ if (env->insn_flags & ASE_MICROMIPS) {
+ env->hflags |= (!!(env->CP0_Config3
+ & (1 << CP0C3_ISA_ON_EXC))
+ << MIPS_HFLAG_M16_SHIFT);
+ }
+}
#endif
void do_interrupt (CPUState *env)
@@ -440,8 +452,7 @@ void do_interrupt (CPUState *env)
if (!(env->CP0_Status & (1 << CP0St_EXL)))
env->CP0_Cause &= ~(1 << CP0Ca_BD);
env->active_tc.PC = (int32_t)0xBFC00480;
- /* Exception handlers are entered in 32-bit mode. */
- env->hflags &= ~(MIPS_HFLAG_M16);
+ set_hflags_for_handler(env);
break;
case EXCP_RESET:
cpu_reset(env);
@@ -461,8 +472,7 @@ void do_interrupt (CPUState *env)
if (!(env->CP0_Status & (1 << CP0St_EXL)))
env->CP0_Cause &= ~(1 << CP0Ca_BD);
env->active_tc.PC = (int32_t)0xBFC00000;
- /* Exception handlers are entered in 32-bit mode. */
- env->hflags &= ~(MIPS_HFLAG_M16);
+ set_hflags_for_handler(env);
break;
case EXCP_EXT_INTERRUPT:
cause = 0;
@@ -581,8 +591,7 @@ void do_interrupt (CPUState *env)
env->active_tc.PC = (int32_t)(env->CP0_EBase & ~0x3ff);
}
env->active_tc.PC += offset;
- /* Exception handlers are entered in 32-bit mode. */
- env->hflags &= ~(MIPS_HFLAG_M16);
+ set_hflags_for_handler(env);
env->CP0_Cause = (env->CP0_Cause & ~(0x1f << CP0Ca_EC)) | (cause << CP0Ca_EC);
break;
default: