linux-kernel - [PATCH v7 08/32] riscv: zicfiss / zicfilp extension csr and bit definitions

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Message-Id: <20241029-v5_user_cfi_series-v7-8-2727ce9936cb@rivosinc.com>
Date: Tue, 29 Oct 2024 16:44:08 -0700
From: Deepak Gupta <debug@...osinc.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
 x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Vlastimil Babka <vbabka@...e.cz>, 
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Conor Dooley <conor@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
 Christian Brauner <brauner@...nel.org>, 
 Peter Zijlstra <peterz@...radead.org>, Oleg Nesterov <oleg@...hat.com>, 
 Eric Biederman <ebiederm@...ssion.com>, Kees Cook <kees@...nel.org>, 
 Jonathan Corbet <corbet@....net>, Shuah Khan <shuah@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
 linux-mm@...ck.org, linux-riscv@...ts.infradead.org, 
 devicetree@...r.kernel.org, linux-arch@...r.kernel.org, 
 linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 alistair.francis@....com, richard.henderson@...aro.org, jim.shu@...ive.com, 
 andybnac@...il.com, kito.cheng@...ive.com, charlie@...osinc.com, 
 atishp@...osinc.com, evan@...osinc.com, cleger@...osinc.com, 
 alexghiti@...osinc.com, samitolvanen@...gle.com, broonie@...nel.org, 
 rick.p.edgecombe@...el.com, Deepak Gupta <debug@...osinc.com>
Subject: [PATCH v7 08/32] riscv: zicfiss / zicfilp extension csr and bit
 definitions

zicfiss and zicfilp extension gets enabled via b3 and b2 in *envcfg CSR.
menvcfg controls enabling for S/HS mode. henvcfg control enabling for VS
while senvcfg controls enabling for U/VU mode.

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

zicfiss adds one new CSR
- CSR_SSP: CSR_SSP contains current shadow stack pointer.

Signed-off-by: Deepak Gupta <debug@...osinc.com>
Reviewed-by: Charlie Jenkins <charlie@...osinc.com>
---
 arch/riscv/include/asm/csr.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 25966995da04..af7ed9bedaee 100644
--- 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)
@@ -197,6 +206,8 @@
 #define ENVCFG_PBMTE			(_AC(1, ULL) << 62)
 #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)
@@ -215,6 +226,11 @@
 #define SMSTATEEN0_HSENVCFG		(_ULL(1) << SMSTATEEN0_HSENVCFG_SHIFT)
 #define SMSTATEEN0_SSTATEEN0_SHIFT	63
 #define SMSTATEEN0_SSTATEEN0		(_ULL(1) << SMSTATEEN0_SSTATEEN0_SHIFT)
+/*
+ * zicfiss user mode csr
+ * CSR_SSP holds current shadow stack pointer.
+ */
+#define CSR_SSP                 0x011

 /* symbolic CSR names: */
 #define CSR_CYCLE		0xc00

-- 
2.34.1