From: Anup Patel Date: Fri, 21 Aug 2020 12:54:14 +0000 (+0530) Subject: lib: sbi: Improve HPM CSR read/write emulation X-Git-Tag: v0.9~71 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ebc8ebc0f84618b2cef8b9b77cc705e4c7c2d8d6;p=platform%2Fkernel%2Fopensbi.git lib: sbi: Improve HPM CSR read/write emulation We improve HPM CSR read/write emulation as follows: 1. Fail for unimplemented counters so that trap is redirected to S-mode which can further help debugging S-mode software. 2. Check permissions in both MCOUNTEREN and SCOUNTEREN for HS-mode and U-mode. 3. Don't check permissions for TIME CSR because we emulate TIME CSR for both Host (HS/U-mode) and Guest (VS/VU-mode). Also, faster TIME CSR read is very helpful for good performance of S-mode software. 4. Don't emulate S-mode CSR read/write to M-mode HPM CSRs because these should not be accessible to S-mode software. Signed-off-by: Anup Patel Reviewed-by: Atish Patra --- diff --git a/lib/sbi/sbi_emulate_csr.c b/lib/sbi/sbi_emulate_csr.c index 62c21a6..bee7761 100644 --- a/lib/sbi/sbi_emulate_csr.c +++ b/lib/sbi/sbi_emulate_csr.c @@ -13,14 +13,31 @@ #include #include #include +#include +#include #include #include +static bool hpm_allowed(int hpm_num, ulong prev_mode, bool virt) +{ + ulong cen = -1UL; + + if (prev_mode <= PRV_S) { + cen &= csr_read(CSR_MCOUNTEREN); + if (virt) + cen &= csr_read(CSR_HCOUNTEREN); + } + if (prev_mode == PRV_U) + cen &= csr_read(CSR_SCOUNTEREN); + + return ((cen >> hpm_num) & 1) ? TRUE : FALSE; +} + int sbi_emulate_csr_read(int csr_num, struct sbi_trap_regs *regs, ulong *csr_val) { int ret = 0; - ulong cen = -1UL; + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr(); ulong prev_mode = (regs->mstatus & MSTATUS_MPP) >> MSTATUS_MPP_SHIFT; #if __riscv_xlen == 32 bool virt = (regs->mstatusH & MSTATUSH_MPV) ? TRUE : FALSE; @@ -28,9 +45,6 @@ int sbi_emulate_csr_read(int csr_num, struct sbi_trap_regs *regs, bool virt = (regs->mstatus & MSTATUS_MPV) ? TRUE : FALSE; #endif - if (prev_mode == PRV_U) - cen = csr_read(CSR_SCOUNTEREN); - switch (csr_num) { case CSR_HTIMEDELTA: if (prev_mode == PRV_S && !virt) @@ -39,31 +53,27 @@ int sbi_emulate_csr_read(int csr_num, struct sbi_trap_regs *regs, ret = SBI_ENOTSUPP; break; case CSR_CYCLE: - if (!((cen >> (CSR_CYCLE - CSR_CYCLE)) & 1)) - return -1; + if (!hpm_allowed(csr_num - CSR_CYCLE, prev_mode, virt)) + return SBI_ENOTSUPP; *csr_val = csr_read(CSR_MCYCLE); break; case CSR_TIME: - if (!((cen >> (CSR_TIME - CSR_CYCLE)) & 1)) - return -1; + /* + * We emulate TIME CSR for both Host (HS/U-mode) and + * Guest (VS/VU-mode). + * + * Faster TIME CSR reads are critical for good performance + * in S-mode software so we don't check CSR permissions. + */ *csr_val = (virt) ? sbi_timer_virt_value(): sbi_timer_value(); break; case CSR_INSTRET: - if (!((cen >> (CSR_INSTRET - CSR_CYCLE)) & 1)) - return -1; + if (!hpm_allowed(csr_num - CSR_CYCLE, prev_mode, virt)) + return SBI_ENOTSUPP; *csr_val = csr_read(CSR_MINSTRET); break; - case CSR_MHPMCOUNTER3: - if (!((cen >> (3 + CSR_MHPMCOUNTER3 - CSR_MHPMCOUNTER3)) & 1)) - return -1; - *csr_val = csr_read(CSR_MHPMCOUNTER3); - break; - case CSR_MHPMCOUNTER4: - if (!((cen >> (3 + CSR_MHPMCOUNTER4 - CSR_MHPMCOUNTER3)) & 1)) - return -1; - *csr_val = csr_read(CSR_MHPMCOUNTER4); - break; + #if __riscv_xlen == 32 case CSR_HTIMEDELTAH: if (prev_mode == PRV_S && !virt) @@ -72,38 +82,61 @@ int sbi_emulate_csr_read(int csr_num, struct sbi_trap_regs *regs, ret = SBI_ENOTSUPP; break; case CSR_CYCLEH: - if (!((cen >> (CSR_CYCLE - CSR_CYCLE)) & 1)) - return -1; + if (!hpm_allowed(csr_num - CSR_CYCLEH, prev_mode, virt)) + return SBI_ENOTSUPP; *csr_val = csr_read(CSR_MCYCLEH); break; case CSR_TIMEH: - if (!((cen >> (CSR_TIME - CSR_CYCLE)) & 1)) - return -1; + /* Refer comments on TIME CSR above. */ *csr_val = (virt) ? sbi_timer_virt_value() >> 32: sbi_timer_value() >> 32; break; case CSR_INSTRETH: - if (!((cen >> (CSR_INSTRET - CSR_CYCLE)) & 1)) - return -1; + if (!hpm_allowed(csr_num - CSR_CYCLEH, prev_mode, virt)) + return SBI_ENOTSUPP; *csr_val = csr_read(CSR_MINSTRETH); break; - case CSR_MHPMCOUNTER3H: - if (!((cen >> (3 + CSR_MHPMCOUNTER3 - CSR_MHPMCOUNTER3)) & 1)) - return -1; - *csr_val = csr_read(CSR_MHPMCOUNTER3H); - break; - case CSR_MHPMCOUNTER4H: - if (!((cen >> (3 + CSR_MHPMCOUNTER4 - CSR_MHPMCOUNTER3)) & 1)) - return -1; - *csr_val = csr_read(CSR_MHPMCOUNTER4H); - break; #endif - case CSR_MHPMEVENT3: - *csr_val = csr_read(CSR_MHPMEVENT3); - break; - case CSR_MHPMEVENT4: - *csr_val = csr_read(CSR_MHPMEVENT4); - break; + +#define switchcase_hpm(__uref, __mref, __csr) \ + case __csr: \ + if ((sbi_hart_mhpm_count(scratch) + 3) <= (__csr - __uref))\ + return SBI_ENOTSUPP; \ + if (!hpm_allowed(__csr - __uref, prev_mode, virt)) \ + return SBI_ENOTSUPP; \ + *csr_val = csr_read(__mref + __csr - __uref); \ + break; +#define switchcase_hpm_2(__uref, __mref, __csr) \ + switchcase_hpm(__uref, __mref, __csr + 0) \ + switchcase_hpm(__uref, __mref, __csr + 1) +#define switchcase_hpm_4(__uref, __mref, __csr) \ + switchcase_hpm_2(__uref, __mref, __csr + 0) \ + switchcase_hpm_2(__uref, __mref, __csr + 2) +#define switchcase_hpm_8(__uref, __mref, __csr) \ + switchcase_hpm_4(__uref, __mref, __csr + 0) \ + switchcase_hpm_4(__uref, __mref, __csr + 4) +#define switchcase_hpm_16(__uref, __mref, __csr) \ + switchcase_hpm_8(__uref, __mref, __csr + 0) \ + switchcase_hpm_8(__uref, __mref, __csr + 8) + + switchcase_hpm(CSR_CYCLE, CSR_MCYCLE, CSR_HPMCOUNTER3) + switchcase_hpm_4(CSR_CYCLE, CSR_MCYCLE, CSR_HPMCOUNTER4) + switchcase_hpm_8(CSR_CYCLE, CSR_MCYCLE, CSR_HPMCOUNTER8) + switchcase_hpm_16(CSR_CYCLE, CSR_MCYCLE, CSR_HPMCOUNTER16) + +#if __riscv_xlen == 32 + switchcase_hpm(CSR_CYCLEH, CSR_MCYCLEH, CSR_HPMCOUNTER3H) + switchcase_hpm_4(CSR_CYCLEH, CSR_MCYCLEH, CSR_HPMCOUNTER4H) + switchcase_hpm_8(CSR_CYCLEH, CSR_MCYCLEH, CSR_HPMCOUNTER8H) + switchcase_hpm_16(CSR_CYCLEH, CSR_MCYCLEH, CSR_HPMCOUNTER16H) +#endif + +#undef switchcase_hpm_16 +#undef switchcase_hpm_8 +#undef switchcase_hpm_4 +#undef switchcase_hpm_2 +#undef switchcase_hpm + default: ret = SBI_ENOTSUPP; break; @@ -134,18 +167,6 @@ int sbi_emulate_csr_write(int csr_num, struct sbi_trap_regs *regs, else ret = SBI_ENOTSUPP; break; - case CSR_CYCLE: - csr_write(CSR_MCYCLE, csr_val); - break; - case CSR_INSTRET: - csr_write(CSR_MINSTRET, csr_val); - break; - case CSR_MHPMCOUNTER3: - csr_write(CSR_MHPMCOUNTER3, csr_val); - break; - case CSR_MHPMCOUNTER4: - csr_write(CSR_MHPMCOUNTER4, csr_val); - break; #if __riscv_xlen == 32 case CSR_HTIMEDELTAH: if (prev_mode == PRV_S && !virt) @@ -153,25 +174,7 @@ int sbi_emulate_csr_write(int csr_num, struct sbi_trap_regs *regs, else ret = SBI_ENOTSUPP; break; - case CSR_CYCLEH: - csr_write(CSR_MCYCLEH, csr_val); - break; - case CSR_INSTRETH: - csr_write(CSR_MINSTRETH, csr_val); - break; - case CSR_MHPMCOUNTER3H: - csr_write(CSR_MHPMCOUNTER3H, csr_val); - break; - case CSR_MHPMCOUNTER4H: - csr_write(CSR_MHPMCOUNTER4H, csr_val); - break; #endif - case CSR_MHPMEVENT3: - csr_write(CSR_MHPMEVENT3, csr_val); - break; - case CSR_MHPMEVENT4: - csr_write(CSR_MHPMEVENT4, csr_val); - break; default: ret = SBI_ENOTSUPP; break;