target/arm: Implement M-profile lazy FP state preservation
The M-profile architecture floating point system supports
lazy FP state preservation, where FP registers are not
pushed to the stack when an exception occurs but are instead
only saved if and when the first FP instruction in the exception
handler is executed. Implement this in QEMU, corresponding
to the check of LSPACT in the pseudocode ExecuteFPCheck().
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190416125744.27770-24-peter.maydell@linaro.org
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index ed30693..0b10aef 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -57,6 +57,7 @@
#define EXCP_NOCP 17 /* v7M NOCP UsageFault */
#define EXCP_INVSTATE 18 /* v7M INVSTATE UsageFault */
#define EXCP_STKOF 19 /* v8M STKOF UsageFault */
+#define EXCP_LAZYFP 20 /* v7M fault during lazy FP stacking */
/* NB: add new EXCP_ defines to the array in arm_log_exception() too */
#define ARMV7M_EXCP_RESET 1
@@ -3172,6 +3173,8 @@
FIELD(TBFLAG_A32, VFPEN, 7, 1)
FIELD(TBFLAG_A32, CONDEXEC, 8, 8)
FIELD(TBFLAG_A32, SCTLR_B, 16, 1)
+/* For M profile only, set if FPCCR.LSPACT is set */
+FIELD(TBFLAG_A32, LSPACT, 18, 1)
/* For M profile only, set if we must create a new FP context */
FIELD(TBFLAG_A32, NEW_FP_CTXT_NEEDED, 19, 1)
/* For M profile only, set if FPCCR.S does not match current security state */
