[RFC PATCH 2/4] lib: riscv: add Ssdbltrp support
Clément Léger
cleger at rivosinc.com
Thu Apr 18 06:54:18 PDT 2024
Add Ssdbltrp trap handler support for S-mode double trap handling. If
the trap is received while in VS-mode, then the trap is redirected to
S-mode. If caught while in HS-mode, then a double trap SSE event is
delivered.
Signed-off-by: Clément Léger <cleger at rivosinc.com>
---
include/sbi/riscv_encoding.h | 3 +++
include/sbi/sbi_ecall_interface.h | 1 +
include/sbi/sbi_hart.h | 3 ++-
include/sbi/sbi_trap_ldst.h | 2 ++
lib/sbi/objects.mk | 1 +
lib/sbi/sbi_double_trap.c | 26 ++++++++++++++++++++++++++
lib/sbi/sbi_hart.c | 4 ++++
lib/sbi/sbi_sse.c | 1 +
lib/sbi/sbi_trap.c | 4 ++++
9 files changed, 44 insertions(+), 1 deletion(-)
create mode 100644 lib/sbi/sbi_double_trap.c
diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
index 477fa3a..8628e5a 100644
--- a/include/sbi/riscv_encoding.h
+++ b/include/sbi/riscv_encoding.h
@@ -32,6 +32,7 @@
#define MSTATUS_TVM _UL(0x00100000)
#define MSTATUS_TW _UL(0x00200000)
#define MSTATUS_TSR _UL(0x00400000)
+#define MSTATUS_SDT _UL(0x01000000)
#define MSTATUS32_SD _UL(0x80000000)
#if __riscv_xlen == 64
#define MSTATUS_UXL _ULL(0x0000000300000000)
@@ -213,6 +214,7 @@
#define ENVCFG_PBMTE (_ULL(1) << 62)
#define ENVCFG_ADUE (_ULL(1) << 61)
#define ENVCFG_CDE (_ULL(1) << 60)
+#define ENVCFG_DTE (_ULL(1) << 59)
#define ENVCFG_CBZE (_UL(1) << 7)
#define ENVCFG_CBCFE (_UL(1) << 6)
#define ENVCFG_CBIE_SHIFT 4
@@ -763,6 +765,7 @@
#define CAUSE_FETCH_PAGE_FAULT 0xc
#define CAUSE_LOAD_PAGE_FAULT 0xd
#define CAUSE_STORE_PAGE_FAULT 0xf
+#define CAUSE_DOUBLE_TRAP 0x10
#define CAUSE_FETCH_GUEST_PAGE_FAULT 0x14
#define CAUSE_LOAD_GUEST_PAGE_FAULT 0x15
#define CAUSE_VIRTUAL_INST_FAULT 0x16
diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
index 0a3b77e..fd1f93d 100644
--- a/include/sbi/sbi_ecall_interface.h
+++ b/include/sbi/sbi_ecall_interface.h
@@ -382,6 +382,7 @@ enum sbi_sse_state {
/* SBI SSE Event IDs. */
#define SBI_SSE_EVENT_LOCAL_RAS 0x00000000
+#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP 0x00000001
#define SBI_SSE_EVENT_LOCAL_PLAT_0_START 0x00004000
#define SBI_SSE_EVENT_LOCAL_PLAT_0_END 0x00007fff
#define SBI_SSE_EVENT_GLOBAL_RAS 0x00008000
diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 10dd90c..a89e6f0 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -65,7 +65,8 @@ enum sbi_hart_extensions {
SBI_HART_EXT_SSCCFG,
/** Hart has Svadu extension */
SBI_HART_EXT_SVADU,
-
+ /** Hart has Ssdbltrp extension */
+ SBI_HART_EXT_SSDBLTRP,
/** Maximum index of Hart extension */
SBI_HART_EXT_MAX,
};
diff --git a/include/sbi/sbi_trap_ldst.h b/include/sbi/sbi_trap_ldst.h
index 8aee316..4c5cc37 100644
--- a/include/sbi/sbi_trap_ldst.h
+++ b/include/sbi/sbi_trap_ldst.h
@@ -28,4 +28,6 @@ int sbi_load_access_handler(struct sbi_trap_context *tcntx);
int sbi_store_access_handler(struct sbi_trap_context *tcntx);
+int sbi_double_trap_handler(struct sbi_trap_context *tcntx);
+
#endif
diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
index 211abad..88bcf10 100644
--- a/lib/sbi/objects.mk
+++ b/lib/sbi/objects.mk
@@ -66,6 +66,7 @@ libsbi-objs-y += sbi_bitops.o
libsbi-objs-y += sbi_console.o
libsbi-objs-y += sbi_domain_context.o
libsbi-objs-y += sbi_domain.o
+libsbi-objs-y += sbi_double_trap.o
libsbi-objs-y += sbi_emulate_csr.o
libsbi-objs-y += sbi_fifo.o
libsbi-objs-y += sbi_fwft.o
diff --git a/lib/sbi/sbi_double_trap.c b/lib/sbi/sbi_double_trap.c
new file mode 100644
index 0000000..15311ee
--- /dev/null
+++ b/lib/sbi/sbi_double_trap.c
@@ -0,0 +1,26 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ * Anup Patel <anup.patel at wdc.com>
+ */
+
+#include <sbi/sbi_console.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_sse.h>
+#include <sbi/sbi_trap.h>
+
+int sbi_double_trap_handler(struct sbi_trap_context *tcntx)
+{
+ struct sbi_trap_regs *regs = &tcntx->regs;
+ const struct sbi_trap_info *trap = &tcntx->trap;
+ bool prev_virt = sbi_regs_from_virt(regs);
+
+ /* Exception was taken in VS-mode, redirect it to S-mode */
+ if (prev_virt)
+ return sbi_trap_redirect(regs, trap);
+
+ return sbi_sse_inject_event(SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP);
+}
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 6908d22..8e4b730 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -117,6 +117,9 @@ static void mstatus_init(struct sbi_scratch *scratch)
menvcfg_val |= ((uint64_t)csr_read(CSR_MENVCFGH)) << 32;
#endif
+ /* Disable double trap by default */
+ menvcfg_val &= ~ENVCFG_DTE;
+
#define __set_menvcfg_ext(__ext, __bits) \
if (sbi_hart_has_extension(scratch, __ext)) \
menvcfg_val |= __bits;
@@ -677,6 +680,7 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
__SBI_HART_EXT_DATA(sscsrind, SBI_HART_EXT_SSCSRIND),
__SBI_HART_EXT_DATA(ssccfg, SBI_HART_EXT_SSCCFG),
__SBI_HART_EXT_DATA(svadu, SBI_HART_EXT_SVADU),
+ __SBI_HART_EXT_DATA(ssdbltrp, SBI_HART_EXT_SSDBLTRP),
};
_Static_assert(SBI_HART_EXT_MAX == array_size(sbi_hart_ext),
diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
index f0729f9..daaeb60 100644
--- a/lib/sbi/sbi_sse.c
+++ b/lib/sbi/sbi_sse.c
@@ -41,6 +41,7 @@
static const uint32_t supported_events[] = {
SBI_SSE_EVENT_LOCAL_RAS,
+ SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP,
SBI_SSE_EVENT_GLOBAL_RAS,
SBI_SSE_EVENT_LOCAL_PMU,
SBI_SSE_EVENT_LOCAL_SOFTWARE,
diff --git a/lib/sbi/sbi_trap.c b/lib/sbi/sbi_trap.c
index 8bd2183..188f2a5 100644
--- a/lib/sbi/sbi_trap.c
+++ b/lib/sbi/sbi_trap.c
@@ -330,6 +330,10 @@ struct sbi_trap_context *sbi_trap_handler(struct sbi_trap_context *tcntx)
rc = sbi_store_access_handler(tcntx);
msg = "store fault handler failed";
break;
+ case CAUSE_DOUBLE_TRAP:
+ rc = sbi_double_trap_handler(tcntx);
+ msg = "double trap handler failed";
+ break;
default:
/* If the trap came from S or U mode, redirect it there */
msg = "trap redirect failed";
--
2.43.0
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