| Message ID | 20210319100450.15491-1-xypron.glpk@gmx.de |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v3,1/1] lib: sbi: illegal CSR 0x306 access in hpm_allowed() | expand |
> -----Original Message----- > From: Heinrich Schuchardt <xypron.glpk@gmx.de> > Sent: 19 March 2021 15:35 > To: Atish Patra <Atish.Patra@wdc.com> > Cc: Anup Patel <Anup.Patel@wdc.com>; Xiang W <wxjstz@126.com>; > OpenSBI <opensbi@lists.infradead.org>; Heinrich Schuchardt > <xypron.glpk@gmx.de> > Subject: [PATCH v3 1/1] lib: sbi: illegal CSR 0x306 access in hpm_allowed() > > The trap handler sbi_emulate_csr_read() invokes hpm_allowed() which > reads CSR 0x306 (mcounteren). The K210 does not support CSR 0x306. While > trying to handle a trap occurring in S-mode code this creates an additional > trap in M-mode. This results in failure to redirect to S-mode and the system > hanging in sbi_hart_hang(). > > In hart_detect_features() we have already determined if CSR 0x306 is > available and stored that information in the scratch area. We can use this > information to decide if CSR 0x306 shall be accessed in hpm_allowed() and > thus avoid the M-mode trap. > > Likewise if CSR scounteren is not available we have to avoid reading CSR > 0x106. > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> Looks good to me. Reviewed-by: Anup Patel <anup.patel@wdc.com> Applied this patch to the riscv/opensbi repo. Thanks, Anup > --- > v3: > remove NOT for SBI_HART_HAS_SCOUNTEREN > v2: > consider scounteren (Xiang W) > --- > lib/sbi/sbi_emulate_csr.c | 19 ++++++++++++++----- > 1 file changed, 14 insertions(+), 5 deletions(-) > > diff --git a/lib/sbi/sbi_emulate_csr.c b/lib/sbi/sbi_emulate_csr.c index > bee7761..c66b5d3 100644 > --- a/lib/sbi/sbi_emulate_csr.c > +++ b/lib/sbi/sbi_emulate_csr.c > @@ -21,14 +21,23 @@ > static bool hpm_allowed(int hpm_num, ulong prev_mode, bool virt) { > ulong cen = -1UL; > + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr(); > > if (prev_mode <= PRV_S) { > - cen &= csr_read(CSR_MCOUNTEREN); > - if (virt) > - cen &= csr_read(CSR_HCOUNTEREN); > + if (sbi_hart_has_feature(scratch, > SBI_HART_HAS_MCOUNTEREN)) { > + cen &= csr_read(CSR_MCOUNTEREN); > + if (virt) > + cen &= csr_read(CSR_HCOUNTEREN); > + } else { > + cen = 0; > + } > + } > + if (prev_mode == PRV_U) { > + if (sbi_hart_has_feature(scratch, > SBI_HART_HAS_SCOUNTEREN)) > + cen &= csr_read(CSR_SCOUNTEREN); > + else > + cen = 0; > } > - if (prev_mode == PRV_U) > - cen &= csr_read(CSR_SCOUNTEREN); > > return ((cen >> hpm_num) & 1) ? TRUE : FALSE; } > -- > 2.30.2
diff --git a/lib/sbi/sbi_emulate_csr.c b/lib/sbi/sbi_emulate_csr.c index bee7761..c66b5d3 100644 --- a/lib/sbi/sbi_emulate_csr.c +++ b/lib/sbi/sbi_emulate_csr.c @@ -21,14 +21,23 @@ static bool hpm_allowed(int hpm_num, ulong prev_mode, bool virt) { ulong cen = -1UL; + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr(); if (prev_mode <= PRV_S) { - cen &= csr_read(CSR_MCOUNTEREN); - if (virt) - cen &= csr_read(CSR_HCOUNTEREN); + if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTEREN)) { + cen &= csr_read(CSR_MCOUNTEREN); + if (virt) + cen &= csr_read(CSR_HCOUNTEREN); + } else { + cen = 0; + } + } + if (prev_mode == PRV_U) { + if (sbi_hart_has_feature(scratch, SBI_HART_HAS_SCOUNTEREN)) + cen &= csr_read(CSR_SCOUNTEREN); + else + cen = 0; } - if (prev_mode == PRV_U) - cen &= csr_read(CSR_SCOUNTEREN); return ((cen >> hpm_num) & 1) ? TRUE : FALSE; }
The trap handler sbi_emulate_csr_read() invokes hpm_allowed() which reads CSR 0x306 (mcounteren). The K210 does not support CSR 0x306. While trying to handle a trap occurring in S-mode code this creates an additional trap in M-mode. This results in failure to redirect to S-mode and the system hanging in sbi_hart_hang(). In hart_detect_features() we have already determined if CSR 0x306 is available and stored that information in the scratch area. We can use this information to decide if CSR 0x306 shall be accessed in hpm_allowed() and thus avoid the M-mode trap. Likewise if CSR scounteren is not available we have to avoid reading CSR 0x106. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> --- v3: remove NOT for SBI_HART_HAS_SCOUNTEREN v2: consider scounteren (Xiang W) --- lib/sbi/sbi_emulate_csr.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) -- 2.30.2