[PATCH 2/5] lib: sbi: add Ssdbltrp ISA extension support
Samuel Holland
samuel.holland at sifive.com
Thu Sep 12 16:22:22 PDT 2024
On 2024-09-12 7:10 AM, Clément Léger wrote:
> 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 | 2 ++
> include/sbi/sbi_ecall_interface.h | 2 ++
> 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 2e4391f..4728c63 100644
> --- a/include/sbi/riscv_encoding.h
> +++ b/include/sbi/riscv_encoding.h
> @@ -213,6 +213,7 @@
> #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 +764,7 @@
> #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 e9a8167..d8077a7 100644
> --- a/include/sbi/sbi_ecall_interface.h
> +++ b/include/sbi/sbi_ecall_interface.h
> @@ -379,7 +379,9 @@ 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_START 0x00004000
This duplicate definition looks like it was added accidentally. With this line
removed:
Reviewed-by: Samuel Holland <samuel.holland at sifive.com>
> #define SBI_SSE_EVENT_LOCAL_PLAT_0_END 0x00007fff
> #define SBI_SSE_EVENT_GLOBAL_RAS 0x00008000
> #define SBI_SSE_EVENT_GLOBAL_PLAT_0_START 0x00004000
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index 81ec061..8aef2a1 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -67,7 +67,8 @@ enum sbi_hart_extensions {
> SBI_HART_EXT_SVADE,
> /** 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 535aa70..7be943f 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..af3c991
> --- /dev/null
> +++ b/lib/sbi/sbi_double_trap.c
> @@ -0,0 +1,26 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2024 Rivos Inc.
> + *
> + * Authors:
> + * Clément Léger <clement.leger at rivosinc.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 cc364fa..d6b9a0a 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;
> @@ -680,6 +683,7 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
> __SBI_HART_EXT_DATA(ssccfg, SBI_HART_EXT_SSCCFG),
> __SBI_HART_EXT_DATA(svade, SBI_HART_EXT_SVADE),
> __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 52172fc..b5f076a 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";
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