| Message ID | 20210319221305.2138412-6-atish.patra@wdc.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | SBI PMU extension support | expand |
> -----Original Message----- > From: Atish Patra <atish.patra@wdc.com> > Sent: 20 March 2021 03:43 > To: opensbi@lists.infradead.org > Cc: Atish Patra <Atish.Patra@wdc.com>; Anup Patel <Anup.Patel@wdc.com> > Subject: [RFC 05/14] lib: sbi: Disable m/scounteren & enable mcountinhibit > > Currently, all bits in mcountern are enabled unconditionally at boot time. > With SBI PMU extension, this should enabled only during performance > monitoring for a particular event except the TM bit. However, this is done > only if mcountinhibit is implemented because the supervisor mode can not > start/stop any event without mcountinhibit. > > Similarly, supervisor should take care enabling scounteren which allows U- > mode to access pmu counters. Disable all bits in scounteren in M-mode. > > Signed-off-by: Atish Patra <atish.patra@wdc.com> Looks good to me. Reviewed-by: Anup Patel <anup.patel@wdc.com> Regards, Anup > --- > lib/sbi/sbi_hart.c | 22 ++++++++++++++++++---- > 1 file changed, 18 insertions(+), 4 deletions(-) > > diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index > 006ec830d86c..b87d1dbedc0b 100644 > --- a/lib/sbi/sbi_hart.c > +++ b/lib/sbi/sbi_hart.c > @@ -51,12 +51,26 @@ static void mstatus_init(struct sbi_scratch *scratch) > > csr_write(CSR_MSTATUS, mstatus_val); > > - /* Enable user/supervisor use of perf counters */ > + /* Disable user mode usage of perf counters */ > if (misa_extension('S') && > sbi_hart_has_feature(scratch, SBI_HART_HAS_SCOUNTEREN)) > - csr_write(CSR_SCOUNTEREN, -1); > - if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTEREN)) > - csr_write(CSR_MCOUNTEREN, -1); > + csr_write(CSR_SCOUNTEREN, 0); > + > + if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTEREN)) { > + if (sbi_hart_has_feature(scratch, > SBI_HART_HAS_MCOUNTINHIBIT)) > + /** > + * Just enable TM bit now. All other counters will be > + * enabled at runtime after S-mode request > + */ > + csr_write(CSR_MCOUNTEREN, 2); > + else > + /* Supervisor mode usage are enabled by default */ > + csr_write(CSR_MCOUNTEREN, -1); > + } > + > + /* Counters will start running at runtime after S-mode request */ > + if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT)) > + csr_write(CSR_MCOUNTINHIBIT, -1); > > /* Disable all interrupts */ > csr_write(CSR_MIE, 0); > -- > 2.25.1
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index 006ec830d86c..b87d1dbedc0b 100644 --- a/lib/sbi/sbi_hart.c +++ b/lib/sbi/sbi_hart.c @@ -51,12 +51,26 @@ static void mstatus_init(struct sbi_scratch *scratch) csr_write(CSR_MSTATUS, mstatus_val); - /* Enable user/supervisor use of perf counters */ + /* Disable user mode usage of perf counters */ if (misa_extension('S') && sbi_hart_has_feature(scratch, SBI_HART_HAS_SCOUNTEREN)) - csr_write(CSR_SCOUNTEREN, -1); - if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTEREN)) - csr_write(CSR_MCOUNTEREN, -1); + csr_write(CSR_SCOUNTEREN, 0); + + if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTEREN)) { + if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT)) + /** + * Just enable TM bit now. All other counters will be + * enabled at runtime after S-mode request + */ + csr_write(CSR_MCOUNTEREN, 2); + else + /* Supervisor mode usage are enabled by default */ + csr_write(CSR_MCOUNTEREN, -1); + } + + /* Counters will start running at runtime after S-mode request */ + if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT)) + csr_write(CSR_MCOUNTINHIBIT, -1); /* Disable all interrupts */ csr_write(CSR_MIE, 0);
Currently, all bits in mcountern are enabled unconditionally at boot time. With SBI PMU extension, this should enabled only during performance monitoring for a particular event except the TM bit. However, this is done only if mcountinhibit is implemented because the supervisor mode can not start/stop any event without mcountinhibit. Similarly, supervisor should take care enabling scounteren which allows U-mode to access pmu counters. Disable all bits in scounteren in M-mode. Signed-off-by: Atish Patra <atish.patra@wdc.com> --- lib/sbi/sbi_hart.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-)