riscv: add Zicfiss / Zicfilp extension CSR and bit definitions

The Zicfiss and Zicfilp extensions are enabled via b3 and b2 in
*envcfg CSRs.  menvcfg controls enabling for S/HS mode.  henvcfg
controls enabling for VS.  senvcfg controls enabling for U/VU mode.

The Zicfilp extension extends *status CSRs to hold an 'expected
landing pad' bit.  A trap or interrupt can occur between an indirect
jmp/call and target instruction.  The 'expected landing pad' bit from
the CPU is recorded into the xstatus CSR so that when the supervisor
performs xret, the 'expected landing pad' state of the CPU can be
restored.

Zicfiss adds one new CSR, CSR_SSP, which contains the current shadow
stack pointer.

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Andreas Korb <andreas.korb@aisec.fraunhofer.de> # QEMU, custom CVA6
Tested-by: Valentin Haudiquet <valentin.haudiquet@canonical.com>
Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-4-b55691eacf4f@rivosinc.com
[pjw@kernel.org: grouped CSR_SSP macro with the other CSR macros; clarified patch description]
Signed-off-by: Paul Walmsley <pjw@kernel.org>

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 4a37a98398ad3b527c280c1e1260d0b53a4ac8d9..55a07e8722ffde8ee515e37b8c4cbda07a767d89 100644 (file)
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -18,6 +18,15 @@
 #define SR_MPP         _AC(0x00001800, UL) /* Previously Machine */
 #define SR_SUM         _AC(0x00040000, UL) /* Supervisor User Memory Access */
 
+/* zicfilp landing pad status bit */
+#define SR_SPELP       _AC(0x00800000, UL)
+#define SR_MPELP       _AC(0x020000000000, UL)
+#ifdef CONFIG_RISCV_M_MODE
+#define SR_ELP         SR_MPELP
+#else
+#define SR_ELP         SR_SPELP
+#endif
+
 #define SR_FS          _AC(0x00006000, UL) /* Floating-point Status */
 #define SR_FS_OFF      _AC(0x00000000, UL)
 #define SR_FS_INITIAL  _AC(0x00002000, UL)
@@ -212,6 +221,8 @@
 #define ENVCFG_PMM_PMLEN_16            (_AC(0x3, ULL) << 32)
 #define ENVCFG_CBZE                    (_AC(1, UL) << 7)
 #define ENVCFG_CBCFE                   (_AC(1, UL) << 6)
+#define ENVCFG_LPE                     (_AC(1, UL) << 2)
+#define ENVCFG_SSE                     (_AC(1, UL) << 3)
 #define ENVCFG_CBIE_SHIFT              4
 #define ENVCFG_CBIE                    (_AC(0x3, UL) << ENVCFG_CBIE_SHIFT)
 #define ENVCFG_CBIE_ILL                        _AC(0x0, UL)
@@ -321,6 +332,9 @@
 #define CSR_STIMECMP           0x14D
 #define CSR_STIMECMPH          0x15D
 
+/* zicfiss user mode csr.  CSR_SSP holds current shadow stack pointer */
+#define CSR_SSP                        0x011
+
 /* xtheadvector symbolic CSR names */
 #define CSR_VXSAT              0x9
 #define CSR_VXRM               0xa