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target/riscv: Introduce elp state and enabling controls for zicfilp

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zicfilp introduces a new state elp ("expected landing pad") in cpu.
During normal execution, elp is idle (NO_LP_EXPECTED) i.e not expecting
landing pad. On an indirect call, elp moves LP_EXPECTED. When elp is
LP_EXPECTED, only a subsquent landing pad instruction can set state back
to NO_LP_EXPECTED. On reset, elp is set to NO_LP_EXPECTED.

zicfilp is enabled via bit2 in *envcfg CSRs. Enabling control for M-mode
is in mseccfg CSR at bit position 10.

On trap, elp state is saved away in *status.
Adds elp to the migration state as well.

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Co-developed-by: Jim Shu <jim.shu@sifive.com>
Co-developed-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241008225010.1861630-4-debug@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Deepak Gupta 2024-10-08 15:49:53 -07:00 • committed by Alistair Francis
parent bd08b22e56
commit 4923f672e3
7 changed files with 68 additions and 1 deletions
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6
target/riscv/cpu_bits.h
View file

@ -552,6 +552,8 @@
#define MSTATUS_TVM 0x00100000 /* since: priv-1.10 */
#define MSTATUS_TW 0x00200000 /* since: priv-1.10 */
#define MSTATUS_TSR 0x00400000 /* since: priv-1.10 */
#define MSTATUS_SPELP 0x00800000 /* zicfilp */
#define MSTATUS_MPELP 0x020000000000 /* zicfilp */
#define MSTATUS_GVA 0x4000000000ULL
#define MSTATUS_MPV 0x8000000000ULL
@ -582,6 +584,7 @@ typedef enum {
#define SSTATUS_XS 0x00018000
#define SSTATUS_SUM 0x00040000 /* since: priv-1.10 */
#define SSTATUS_MXR 0x00080000
#define SSTATUS_SPELP MSTATUS_SPELP /* zicfilp */
#define SSTATUS64_UXL 0x0000000300000000ULL
@ -754,6 +757,7 @@ typedef enum RISCVException {
/* Execution environment configuration bits */
#define MENVCFG_FIOM BIT(0)
#define MENVCFG_LPE BIT(2) /* zicfilp */
#define MENVCFG_CBIE (3UL << 4)
#define MENVCFG_CBCFE BIT(6)
#define MENVCFG_CBZE BIT(7)
@ -767,11 +771,13 @@ typedef enum RISCVException {
#define MENVCFGH_STCE BIT(31)
#define SENVCFG_FIOM MENVCFG_FIOM
#define SENVCFG_LPE MENVCFG_LPE
#define SENVCFG_CBIE MENVCFG_CBIE
#define SENVCFG_CBCFE MENVCFG_CBCFE
#define SENVCFG_CBZE MENVCFG_CBZE
#define HENVCFG_FIOM MENVCFG_FIOM
#define HENVCFG_LPE MENVCFG_LPE
#define HENVCFG_CBIE MENVCFG_CBIE
#define HENVCFG_CBCFE MENVCFG_CBCFE
#define HENVCFG_CBZE MENVCFG_CBZE