[RFC PATCH 2/4] lib: riscv: add Ssdbltrp support
Anup Patel
anup at brainfault.org
Mon Jun 10 04:06:52 PDT 2024
On Thu, Apr 18, 2024 at 7:25 PM Clément Léger <cleger at rivosinc.com> 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 | 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
Please send a patch for SBI spec first.
> #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);
> +}
No need for a separate file, we can have this function directly in
sbi_trap.c as a static function.
> 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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Regards,
Anup
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