> -----Original Message-----
> From: Daniel Henrique Barboza <dbarb...@ventanamicro.com>
> Sent: Wednesday, January 10, 2024 6:04 AM
> To: Alvin Che-Chia Chang(張哲嘉) <alvi...@andestech.com>;
> qemu-ri...@nongnu.org; qemu-devel@nongnu.org
> Cc: alistair.fran...@wdc.com; bin.m...@windriver.com;
> liwei1...@gmail.com; zhiwei_...@linux.alibaba.com
> Subject: Re: [PATCH v2] target/riscv: Implement optional CSR mcontext of
> debug Sdtrig extension
>
>
> On 12/19/23 09:32, Alvin Chang wrote:
> > The debug Sdtrig extension defines an CSR "mcontext". This commit
> > implements its predicate and read/write operations into CSR table.
> > Its value is reset as 0 when the trigger module is reset.
> >
> > Signed-off-by: Alvin Chang <alvi...@andestech.com>
> > ---
>
> The patch per se LGTM:
>
> Reviewed-by: Daniel Henrique Barboza <dbarb...@ventanamicro.com>
Thank you!!
>
>
> But I have a question: shouldn't we just go ahead and add the 'sdtrig'
> extension?
> We have a handful of its CSRs already. Adding the extension would also add
> 'sdtrig'
> in riscv,isa, allowing software to be aware of its existence in QEMU.
I agree with you. I can prepare another PR for adding 'sdtrig' extension.
BTW, currently we have "riscv_cpu_cfg(env)->debug" to control those trigger
module CSRs.
Maybe we can just remove "debug" and use "sdtrig" instead ?
Alvin
>
>
> Thanks,
>
> Daniel
>
>
>
> > Changes from v1: Remove dedicated cfg, always implement mcontext.
> >
> > target/riscv/cpu.h | 1 +
> > target/riscv/cpu_bits.h | 7 +++++++
> > target/riscv/csr.c | 36 +++++++++++++++++++++++++++++++-----
> > target/riscv/debug.c | 2 ++
> > 4 files changed, 41 insertions(+), 5 deletions(-)
> >
> > diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index
> > d74b361..e117641 100644
> > --- a/target/riscv/cpu.h
> > +++ b/target/riscv/cpu.h
> > @@ -345,6 +345,7 @@ struct CPUArchState {
> > target_ulong tdata1[RV_MAX_TRIGGERS];
> > target_ulong tdata2[RV_MAX_TRIGGERS];
> > target_ulong tdata3[RV_MAX_TRIGGERS];
> > + target_ulong mcontext;
> > struct CPUBreakpoint *cpu_breakpoint[RV_MAX_TRIGGERS];
> > struct CPUWatchpoint *cpu_watchpoint[RV_MAX_TRIGGERS];
> > QEMUTimer *itrigger_timer[RV_MAX_TRIGGERS]; diff --git
> > a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h index
> > ebd7917..3296648 100644
> > --- a/target/riscv/cpu_bits.h
> > +++ b/target/riscv/cpu_bits.h
> > @@ -361,6 +361,7 @@
> > #define CSR_TDATA2 0x7a2
> > #define CSR_TDATA3 0x7a3
> > #define CSR_TINFO 0x7a4
> > +#define CSR_MCONTEXT 0x7a8
> >
> > /* Debug Mode Registers */
> > #define CSR_DCSR 0x7b0
> > @@ -905,4 +906,10 @@ typedef enum RISCVException {
> > /* JVT CSR bits */
> > #define JVT_MODE 0x3F
> > #define JVT_BASE (~0x3F)
> > +
> > +/* Debug Sdtrig CSR masks */
> > +#define MCONTEXT32 0x0000003F
> > +#define MCONTEXT64
> 0x0000000000001FFFULL
> > +#define MCONTEXT32_HCONTEXT 0x0000007F
> > +#define MCONTEXT64_HCONTEXT
> 0x0000000000003FFFULL
> > #endif
> > diff --git a/target/riscv/csr.c b/target/riscv/csr.c index
> > fde7ce1..ff1e128 100644
> > --- a/target/riscv/csr.c
> > +++ b/target/riscv/csr.c
> > @@ -3900,6 +3900,31 @@ static RISCVException read_tinfo(CPURISCVState
> *env, int csrno,
> > return RISCV_EXCP_NONE;
> > }
> >
> > +static RISCVException read_mcontext(CPURISCVState *env, int csrno,
> > + target_ulong *val) {
> > + *val = env->mcontext;
> > + return RISCV_EXCP_NONE;
> > +}
> > +
> > +static RISCVException write_mcontext(CPURISCVState *env, int csrno,
> > + target_ulong val) {
> > + bool rv32 = riscv_cpu_mxl(env) == MXL_RV32 ? true : false;
> > + int32_t mask;
> > +
> > + if (riscv_has_ext(env, RVH)) {
> > + /* Spec suggest 7-bit for RV32 and 14-bit for RV64 w/ H extension
> */
> > + mask = rv32 ? MCONTEXT32_HCONTEXT :
> MCONTEXT64_HCONTEXT;
> > + } else {
> > + /* Spec suggest 6-bit for RV32 and 13-bit for RV64 w/o H
> extension */
> > + mask = rv32 ? MCONTEXT32 : MCONTEXT64;
> > + }
> > +
> > + env->mcontext = val & mask;
> > + return RISCV_EXCP_NONE;
> > +}
> > +
> > /*
> > * Functions to access Pointer Masking feature registers
> > * We have to check if current priv lvl could modify @@ -4794,11
> > +4819,12 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
> > [CSR_PMPADDR15] = { "pmpaddr15", pmp, read_pmpaddr,
> > write_pmpaddr },
> >
> > /* Debug CSRs */
> > - [CSR_TSELECT] = { "tselect", debug, read_tselect, write_tselect },
> > - [CSR_TDATA1] = { "tdata1", debug, read_tdata,
> write_tdata },
> > - [CSR_TDATA2] = { "tdata2", debug, read_tdata,
> write_tdata },
> > - [CSR_TDATA3] = { "tdata3", debug, read_tdata,
> write_tdata },
> > - [CSR_TINFO] = { "tinfo", debug, read_tinfo,
> write_ignore },
> > + [CSR_TSELECT] = { "tselect", debug, read_tselect,
> write_tselect },
> > + [CSR_TDATA1] = { "tdata1", debug, read_tdata,
> write_tdata },
> > + [CSR_TDATA2] = { "tdata2", debug, read_tdata,
> write_tdata },
> > + [CSR_TDATA3] = { "tdata3", debug, read_tdata,
> write_tdata },
> > + [CSR_TINFO] = { "tinfo", debug, read_tinfo,
> write_ignore },
> > + [CSR_MCONTEXT] = { "mcontext", debug, read_mcontext,
> > + write_mcontext },
> >
> > /* User Pointer Masking */
> > [CSR_UMTE] = { "umte", pointer_masking, read_umte,
> write_umte },
> > diff --git a/target/riscv/debug.c b/target/riscv/debug.c index
> > 4945d1a..e30d99c 100644
> > --- a/target/riscv/debug.c
> > +++ b/target/riscv/debug.c
> > @@ -940,4 +940,6 @@ void riscv_trigger_reset_hold(CPURISCVState *env)
> > env->cpu_watchpoint[i] = NULL;
> > timer_del(env->itrigger_timer[i]);
> > }
> > +
> > + env->mcontext = 0;
> > }
