| Message ID | 20221227064812.1903326-2-bmeng@tinylab.org |
|---|---|
| State | New |
| Headers | show |
| Series | hw/riscv: Improve Spike HTIF emulation fidelity | expand |
On 12/27/22 03:48, Bin Meng wrote: > The Spike HTIF is poorly documented. The only relevant info we can > get from the internet is from Andrew Waterman at [1]. > > Add a comment block before htif_handle_tohost_write() to explain > the tohost register format, and use meaningful macros intead of s/intead/instead > magic numbers in the codes. > > While we are here, corret 2 multi-line comment blocks that have s/corret/correct Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com> > wrong format. > > Link: https://github.com/riscv-software-src/riscv-isa-sim/issues/364 [1] > Signed-off-by: Bin Meng <bmeng@tinylab.org> > --- > > hw/char/riscv_htif.c | 72 ++++++++++++++++++++++++++++++++------------ > 1 file changed, 52 insertions(+), 20 deletions(-) > > diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c > index 6577f0e640..088556bb04 100644 > --- a/hw/char/riscv_htif.c > +++ b/hw/char/riscv_htif.c > @@ -38,6 +38,16 @@ > } \ > } while (0) > > +#define HTIF_DEV_SHIFT 56 > +#define HTIF_CMD_SHIFT 48 > + > +#define HTIF_DEV_SYSTEM 0 > +#define HTIF_DEV_CONSOLE 1 > + > +#define HTIF_SYSTEM_CMD_SYSCALL 0 > +#define HTIF_CONSOLE_CMD_GETC 0 > +#define HTIF_CONSOLE_CMD_PUTC 1 > + > static uint64_t fromhost_addr, tohost_addr; > static int address_symbol_set; > > @@ -81,9 +91,11 @@ static void htif_recv(void *opaque, const uint8_t *buf, int size) > return; > } > > - /* TODO - we need to check whether mfromhost is zero which indicates > - the device is ready to receive. The current implementation > - will drop characters */ > + /* > + * TODO - we need to check whether mfromhost is zero which indicates > + * the device is ready to receive. The current implementation > + * will drop characters > + */ > > uint64_t val_written = htifstate->pending_read; > uint64_t resp = 0x100 | *buf; > @@ -110,10 +122,30 @@ static int htif_be_change(void *opaque) > return 0; > } > > +/* > + * See below the tohost register format. > + * > + * Bits 63:56 indicate the "device". > + * Bits 55:48 indicate the "command". > + * > + * Device 0 is the syscall device, which is used to emulate Unixy syscalls. > + * It only implements command 0, which has two subfunctions: > + * - If bit 0 is clear, then bits 47:0 represent a pointer to a struct > + * describing the syscall. > + * - If bit 1 is set, then bits 47:1 represent an exit code, with a zero > + * value indicating success and other values indicating failure. > + * > + * Device 1 is the blocking character device. > + * - Command 0 reads a character > + * - Command 1 writes a character from the 8 LSBs of tohost > + * > + * For RV32, the tohost register is zero-extended, so only device=0 and > + * command=0 (i.e. HTIF syscalls/exit codes) are supported. > + */ > static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > { > - uint8_t device = val_written >> 56; > - uint8_t cmd = val_written >> 48; > + uint8_t device = val_written >> HTIF_DEV_SHIFT; > + uint8_t cmd = val_written >> HTIF_CMD_SHIFT; > uint64_t payload = val_written & 0xFFFFFFFFFFFFULL; > int resp = 0; > > @@ -125,9 +157,9 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > * 0: riscv-tests Pass/Fail Reporting Only (no syscall proxy) > * 1: Console > */ > - if (unlikely(device == 0x0)) { > + if (unlikely(device == HTIF_DEV_SYSTEM)) { > /* frontend syscall handler, shutdown and exit code support */ > - if (cmd == 0x0) { > + if (cmd == HTIF_SYSTEM_CMD_SYSCALL) { > if (payload & 0x1) { > /* exit code */ > int exit_code = payload >> 1; > @@ -138,14 +170,14 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > } else { > qemu_log("HTIF device %d: unknown command\n", device); > } > - } else if (likely(device == 0x1)) { > + } else if (likely(device == HTIF_DEV_CONSOLE)) { > /* HTIF Console */ > - if (cmd == 0x0) { > + if (cmd == HTIF_CONSOLE_CMD_GETC) { > /* this should be a queue, but not yet implemented as such */ > htifstate->pending_read = val_written; > htifstate->env->mtohost = 0; /* clear to indicate we read */ > return; > - } else if (cmd == 0x1) { > + } else if (cmd == HTIF_CONSOLE_CMD_PUTC) { > qemu_chr_fe_write(&htifstate->chr, (uint8_t *)&payload, 1); > resp = 0x100 | (uint8_t)payload; > } else { > @@ -157,15 +189,15 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > " payload: %016" PRIx64, device, cmd, payload & 0xFF, payload); > } > /* > - * - latest bbl does not set fromhost to 0 if there is a value in tohost > - * - with this code enabled, qemu hangs waiting for fromhost to go to 0 > - * - with this code disabled, qemu works with bbl priv v1.9.1 and v1.10 > - * - HTIF needs protocol documentation and a more complete state machine > - > - while (!htifstate->fromhost_inprogress && > - htifstate->env->mfromhost != 0x0) { > - } > - */ > + * Latest bbl does not set fromhost to 0 if there is a value in tohost. > + * With this code enabled, qemu hangs waiting for fromhost to go to 0. > + * With this code disabled, qemu works with bbl priv v1.9.1 and v1.10. > + * HTIF needs protocol documentation and a more complete state machine. > + * > + * while (!htifstate->fromhost_inprogress && > + * htifstate->env->mfromhost != 0x0) { > + * } > + */ > htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16); > htifstate->env->mtohost = 0; /* clear to indicate we read */ > } > @@ -196,7 +228,7 @@ static uint64_t htif_mm_read(void *opaque, hwaddr addr, unsigned size) > > /* CPU wrote to an HTIF register */ > static void htif_mm_write(void *opaque, hwaddr addr, > - uint64_t value, unsigned size) > + uint64_t value, unsigned size) > { > HTIFState *htifstate = opaque; > if (addr == TOHOST_OFFSET1) {
On Tue, Dec 27, 2022 at 4:50 PM Bin Meng <bmeng@tinylab.org> wrote: > > The Spike HTIF is poorly documented. The only relevant info we can > get from the internet is from Andrew Waterman at [1]. > > Add a comment block before htif_handle_tohost_write() to explain > the tohost register format, and use meaningful macros intead of > magic numbers in the codes. > > While we are here, corret 2 multi-line comment blocks that have > wrong format. > > Link: https://github.com/riscv-software-src/riscv-isa-sim/issues/364 [1] > Signed-off-by: Bin Meng <bmeng@tinylab.org> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Alistair > --- > > hw/char/riscv_htif.c | 72 ++++++++++++++++++++++++++++++++------------ > 1 file changed, 52 insertions(+), 20 deletions(-) > > diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c > index 6577f0e640..088556bb04 100644 > --- a/hw/char/riscv_htif.c > +++ b/hw/char/riscv_htif.c > @@ -38,6 +38,16 @@ > } \ > } while (0) > > +#define HTIF_DEV_SHIFT 56 > +#define HTIF_CMD_SHIFT 48 > + > +#define HTIF_DEV_SYSTEM 0 > +#define HTIF_DEV_CONSOLE 1 > + > +#define HTIF_SYSTEM_CMD_SYSCALL 0 > +#define HTIF_CONSOLE_CMD_GETC 0 > +#define HTIF_CONSOLE_CMD_PUTC 1 > + > static uint64_t fromhost_addr, tohost_addr; > static int address_symbol_set; > > @@ -81,9 +91,11 @@ static void htif_recv(void *opaque, const uint8_t *buf, int size) > return; > } > > - /* TODO - we need to check whether mfromhost is zero which indicates > - the device is ready to receive. The current implementation > - will drop characters */ > + /* > + * TODO - we need to check whether mfromhost is zero which indicates > + * the device is ready to receive. The current implementation > + * will drop characters > + */ > > uint64_t val_written = htifstate->pending_read; > uint64_t resp = 0x100 | *buf; > @@ -110,10 +122,30 @@ static int htif_be_change(void *opaque) > return 0; > } > > +/* > + * See below the tohost register format. > + * > + * Bits 63:56 indicate the "device". > + * Bits 55:48 indicate the "command". > + * > + * Device 0 is the syscall device, which is used to emulate Unixy syscalls. > + * It only implements command 0, which has two subfunctions: > + * - If bit 0 is clear, then bits 47:0 represent a pointer to a struct > + * describing the syscall. > + * - If bit 1 is set, then bits 47:1 represent an exit code, with a zero > + * value indicating success and other values indicating failure. > + * > + * Device 1 is the blocking character device. > + * - Command 0 reads a character > + * - Command 1 writes a character from the 8 LSBs of tohost > + * > + * For RV32, the tohost register is zero-extended, so only device=0 and > + * command=0 (i.e. HTIF syscalls/exit codes) are supported. > + */ > static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > { > - uint8_t device = val_written >> 56; > - uint8_t cmd = val_written >> 48; > + uint8_t device = val_written >> HTIF_DEV_SHIFT; > + uint8_t cmd = val_written >> HTIF_CMD_SHIFT; > uint64_t payload = val_written & 0xFFFFFFFFFFFFULL; > int resp = 0; > > @@ -125,9 +157,9 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > * 0: riscv-tests Pass/Fail Reporting Only (no syscall proxy) > * 1: Console > */ > - if (unlikely(device == 0x0)) { > + if (unlikely(device == HTIF_DEV_SYSTEM)) { > /* frontend syscall handler, shutdown and exit code support */ > - if (cmd == 0x0) { > + if (cmd == HTIF_SYSTEM_CMD_SYSCALL) { > if (payload & 0x1) { > /* exit code */ > int exit_code = payload >> 1; > @@ -138,14 +170,14 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > } else { > qemu_log("HTIF device %d: unknown command\n", device); > } > - } else if (likely(device == 0x1)) { > + } else if (likely(device == HTIF_DEV_CONSOLE)) { > /* HTIF Console */ > - if (cmd == 0x0) { > + if (cmd == HTIF_CONSOLE_CMD_GETC) { > /* this should be a queue, but not yet implemented as such */ > htifstate->pending_read = val_written; > htifstate->env->mtohost = 0; /* clear to indicate we read */ > return; > - } else if (cmd == 0x1) { > + } else if (cmd == HTIF_CONSOLE_CMD_PUTC) { > qemu_chr_fe_write(&htifstate->chr, (uint8_t *)&payload, 1); > resp = 0x100 | (uint8_t)payload; > } else { > @@ -157,15 +189,15 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) > " payload: %016" PRIx64, device, cmd, payload & 0xFF, payload); > } > /* > - * - latest bbl does not set fromhost to 0 if there is a value in tohost > - * - with this code enabled, qemu hangs waiting for fromhost to go to 0 > - * - with this code disabled, qemu works with bbl priv v1.9.1 and v1.10 > - * - HTIF needs protocol documentation and a more complete state machine > - > - while (!htifstate->fromhost_inprogress && > - htifstate->env->mfromhost != 0x0) { > - } > - */ > + * Latest bbl does not set fromhost to 0 if there is a value in tohost. > + * With this code enabled, qemu hangs waiting for fromhost to go to 0. > + * With this code disabled, qemu works with bbl priv v1.9.1 and v1.10. > + * HTIF needs protocol documentation and a more complete state machine. > + * > + * while (!htifstate->fromhost_inprogress && > + * htifstate->env->mfromhost != 0x0) { > + * } > + */ > htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16); > htifstate->env->mtohost = 0; /* clear to indicate we read */ > } > @@ -196,7 +228,7 @@ static uint64_t htif_mm_read(void *opaque, hwaddr addr, unsigned size) > > /* CPU wrote to an HTIF register */ > static void htif_mm_write(void *opaque, hwaddr addr, > - uint64_t value, unsigned size) > + uint64_t value, unsigned size) > { > HTIFState *htifstate = opaque; > if (addr == TOHOST_OFFSET1) { > -- > 2.34.1 > >
diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c index 6577f0e640..088556bb04 100644 --- a/hw/char/riscv_htif.c +++ b/hw/char/riscv_htif.c @@ -38,6 +38,16 @@ } \ } while (0) +#define HTIF_DEV_SHIFT 56 +#define HTIF_CMD_SHIFT 48 + +#define HTIF_DEV_SYSTEM 0 +#define HTIF_DEV_CONSOLE 1 + +#define HTIF_SYSTEM_CMD_SYSCALL 0 +#define HTIF_CONSOLE_CMD_GETC 0 +#define HTIF_CONSOLE_CMD_PUTC 1 + static uint64_t fromhost_addr, tohost_addr; static int address_symbol_set; @@ -81,9 +91,11 @@ static void htif_recv(void *opaque, const uint8_t *buf, int size) return; } - /* TODO - we need to check whether mfromhost is zero which indicates - the device is ready to receive. The current implementation - will drop characters */ + /* + * TODO - we need to check whether mfromhost is zero which indicates + * the device is ready to receive. The current implementation + * will drop characters + */ uint64_t val_written = htifstate->pending_read; uint64_t resp = 0x100 | *buf; @@ -110,10 +122,30 @@ static int htif_be_change(void *opaque) return 0; } +/* + * See below the tohost register format. + * + * Bits 63:56 indicate the "device". + * Bits 55:48 indicate the "command". + * + * Device 0 is the syscall device, which is used to emulate Unixy syscalls. + * It only implements command 0, which has two subfunctions: + * - If bit 0 is clear, then bits 47:0 represent a pointer to a struct + * describing the syscall. + * - If bit 1 is set, then bits 47:1 represent an exit code, with a zero + * value indicating success and other values indicating failure. + * + * Device 1 is the blocking character device. + * - Command 0 reads a character + * - Command 1 writes a character from the 8 LSBs of tohost + * + * For RV32, the tohost register is zero-extended, so only device=0 and + * command=0 (i.e. HTIF syscalls/exit codes) are supported. + */ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) { - uint8_t device = val_written >> 56; - uint8_t cmd = val_written >> 48; + uint8_t device = val_written >> HTIF_DEV_SHIFT; + uint8_t cmd = val_written >> HTIF_CMD_SHIFT; uint64_t payload = val_written & 0xFFFFFFFFFFFFULL; int resp = 0; @@ -125,9 +157,9 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) * 0: riscv-tests Pass/Fail Reporting Only (no syscall proxy) * 1: Console */ - if (unlikely(device == 0x0)) { + if (unlikely(device == HTIF_DEV_SYSTEM)) { /* frontend syscall handler, shutdown and exit code support */ - if (cmd == 0x0) { + if (cmd == HTIF_SYSTEM_CMD_SYSCALL) { if (payload & 0x1) { /* exit code */ int exit_code = payload >> 1; @@ -138,14 +170,14 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) } else { qemu_log("HTIF device %d: unknown command\n", device); } - } else if (likely(device == 0x1)) { + } else if (likely(device == HTIF_DEV_CONSOLE)) { /* HTIF Console */ - if (cmd == 0x0) { + if (cmd == HTIF_CONSOLE_CMD_GETC) { /* this should be a queue, but not yet implemented as such */ htifstate->pending_read = val_written; htifstate->env->mtohost = 0; /* clear to indicate we read */ return; - } else if (cmd == 0x1) { + } else if (cmd == HTIF_CONSOLE_CMD_PUTC) { qemu_chr_fe_write(&htifstate->chr, (uint8_t *)&payload, 1); resp = 0x100 | (uint8_t)payload; } else { @@ -157,15 +189,15 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written) " payload: %016" PRIx64, device, cmd, payload & 0xFF, payload); } /* - * - latest bbl does not set fromhost to 0 if there is a value in tohost - * - with this code enabled, qemu hangs waiting for fromhost to go to 0 - * - with this code disabled, qemu works with bbl priv v1.9.1 and v1.10 - * - HTIF needs protocol documentation and a more complete state machine - - while (!htifstate->fromhost_inprogress && - htifstate->env->mfromhost != 0x0) { - } - */ + * Latest bbl does not set fromhost to 0 if there is a value in tohost. + * With this code enabled, qemu hangs waiting for fromhost to go to 0. + * With this code disabled, qemu works with bbl priv v1.9.1 and v1.10. + * HTIF needs protocol documentation and a more complete state machine. + * + * while (!htifstate->fromhost_inprogress && + * htifstate->env->mfromhost != 0x0) { + * } + */ htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16); htifstate->env->mtohost = 0; /* clear to indicate we read */ } @@ -196,7 +228,7 @@ static uint64_t htif_mm_read(void *opaque, hwaddr addr, unsigned size) /* CPU wrote to an HTIF register */ static void htif_mm_write(void *opaque, hwaddr addr, - uint64_t value, unsigned size) + uint64_t value, unsigned size) { HTIFState *htifstate = opaque; if (addr == TOHOST_OFFSET1) {
The Spike HTIF is poorly documented. The only relevant info we can get from the internet is from Andrew Waterman at [1]. Add a comment block before htif_handle_tohost_write() to explain the tohost register format, and use meaningful macros intead of magic numbers in the codes. While we are here, corret 2 multi-line comment blocks that have wrong format. Link: https://github.com/riscv-software-src/riscv-isa-sim/issues/364 [1] Signed-off-by: Bin Meng <bmeng@tinylab.org> --- hw/char/riscv_htif.c | 72 ++++++++++++++++++++++++++++++++------------ 1 file changed, 52 insertions(+), 20 deletions(-)