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author | Himanshu Chauhan <hchauhan@ventanamicro.com> | 2023-07-12 10:04:33 +0530 |
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committer | Anup Patel <anup@brainfault.org> | 2023-07-13 12:42:09 +0530 |
commit | 5dd8db5b10fc03aeded76407aecb731a8a9f1cfa (patch) | |
tree | fd2babcf5a42a726cf0c0bc0532d89532ac2205e /lib/sbi/sbi_hart.c | |
parent | f3fdd041acf5bfb9c261c1e8a909e9b0d78c03e8 (diff) | |
download | opensbi-5dd8db5b10fc03aeded76407aecb731a8a9f1cfa.zip opensbi-5dd8db5b10fc03aeded76407aecb731a8a9f1cfa.tar.gz opensbi-5dd8db5b10fc03aeded76407aecb731a8a9f1cfa.tar.bz2 |
lib: sbi: Add support for Smepmp
- If Smepmp is enabled, the access flags of an entry are determined based on
truth table defined in Smepmp.
- First PMP entry (index 0) is reserved.
- Existing boot PMP entries start from index 1.
- Since enabling Smepmp revokes the access privileges of the M-mode software
on S/U-mode region, first PMP entry is used to map/unmap the shared memory
between M and S/U-mode. This allows a temporary access window for the M-mode
software to read/write to S/U-mode memory region.
Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Diffstat (limited to 'lib/sbi/sbi_hart.c')
-rw-r--r-- | lib/sbi/sbi_hart.c | 134 |
1 files changed, 115 insertions, 19 deletions
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index 4dfa170..12f9c7e 100644 --- a/lib/sbi/sbi_hart.c +++ b/lib/sbi/sbi_hart.c @@ -284,11 +284,75 @@ unsigned int sbi_hart_mhpm_bits(struct sbi_scratch *scratch) return hfeatures->mhpm_bits; } +/* + * Returns Smepmp flags for a given domain and region based on permissions. + */ +unsigned int sbi_hart_get_smepmp_flags(struct sbi_scratch *scratch, + struct sbi_domain *dom, + struct sbi_domain_memregion *reg) +{ + unsigned int pmp_flags = 0; + + if (SBI_DOMAIN_MEMREGION_IS_SHARED(reg->flags)) { + /* Read only for both M and SU modes */ + if (SBI_DOMAIN_MEMREGION_IS_SUR_MR(reg->flags)) + pmp_flags = (PMP_R | PMP_W | PMP_X); + + /* Execute for SU but Read/Execute for M mode */ + else if (SBI_DOMAIN_MEMREGION_IS_SUX_MRX(reg->flags)) + /* locked region */ + pmp_flags = (PMP_L | PMP_W | PMP_X); + + /* Execute only for both M and SU modes */ + else if (SBI_DOMAIN_MEMREGION_IS_SUX_MX(reg->flags)) + pmp_flags = (PMP_L | PMP_W); + + /* Read/Write for both M and SU modes */ + else if (SBI_DOMAIN_MEMREGION_IS_SURW_MRW(reg->flags)) + pmp_flags = (PMP_W | PMP_X); + + /* Read only for SU mode but Read/Write for M mode */ + else if (SBI_DOMAIN_MEMREGION_IS_SUR_MRW(reg->flags)) + pmp_flags = (PMP_W); + } else if (SBI_DOMAIN_MEMREGION_M_ONLY_ACCESS(reg->flags)) { + /* + * When smepmp is supported and used, M region cannot have RWX + * permissions on any region. + */ + if ((reg->flags & SBI_DOMAIN_MEMREGION_M_ACCESS_MASK) + == SBI_DOMAIN_MEMREGION_M_RWX) { + sbi_printf("%s: M-mode only regions cannot have" + "RWX permissions\n", __func__); + return 0; + } + + /* M-mode only access regions are always locked */ + pmp_flags |= PMP_L; + + if (reg->flags & SBI_DOMAIN_MEMREGION_M_READABLE) + pmp_flags |= PMP_R; + if (reg->flags & SBI_DOMAIN_MEMREGION_M_WRITABLE) + pmp_flags |= PMP_W; + if (reg->flags & SBI_DOMAIN_MEMREGION_M_EXECUTABLE) + pmp_flags |= PMP_X; + } else if (SBI_DOMAIN_MEMREGION_SU_ONLY_ACCESS(reg->flags)) { + if (reg->flags & SBI_DOMAIN_MEMREGION_SU_READABLE) + pmp_flags |= PMP_R; + if (reg->flags & SBI_DOMAIN_MEMREGION_SU_WRITABLE) + pmp_flags |= PMP_W; + if (reg->flags & SBI_DOMAIN_MEMREGION_SU_EXECUTABLE) + pmp_flags |= PMP_X; + } + + return pmp_flags; +} + int sbi_hart_pmp_configure(struct sbi_scratch *scratch) { struct sbi_domain_memregion *reg; struct sbi_domain *dom = sbi_domain_thishart_ptr(); - unsigned int pmp_idx = 0, pmp_flags, pmp_bits, pmp_gran_log2; + unsigned int pmp_idx = 0; + unsigned int pmp_flags, pmp_bits, pmp_gran_log2; unsigned int pmp_count = sbi_hart_pmp_count(scratch); unsigned long pmp_addr = 0, pmp_addr_max = 0; @@ -299,36 +363,68 @@ int sbi_hart_pmp_configure(struct sbi_scratch *scratch) pmp_bits = sbi_hart_pmp_addrbits(scratch) - 1; pmp_addr_max = (1UL << pmp_bits) | ((1UL << pmp_bits) - 1); + if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMEPMP)) { + /* Reserve first entry for dynamic shared mappings */ + pmp_idx = SBI_SMEPMP_RESV_ENTRY + 1; + + /* + * Set the RLB and clear MML so that, we can write to + * entries without enforcement even if some entries + * are locked. + */ + csr_set(CSR_MSECCFG, MSECCFG_RLB); + csr_clear(CSR_MSECCFG, MSECCFG_MML); + + /* Disable the reserved entry */ + pmp_disable(SBI_SMEPMP_RESV_ENTRY); + } + sbi_domain_for_each_memregion(dom, reg) { if (pmp_count <= pmp_idx) break; pmp_flags = 0; - /* - * If permissions are to be enforced for all modes on this - * region, the lock bit should be set. - */ - if (reg->flags & SBI_DOMAIN_MEMREGION_ENF_PERMISSIONS) - pmp_flags |= PMP_L; - - if (reg->flags & SBI_DOMAIN_MEMREGION_SU_READABLE) - pmp_flags |= PMP_R; - if (reg->flags & SBI_DOMAIN_MEMREGION_SU_WRITABLE) - pmp_flags |= PMP_W; - if (reg->flags & SBI_DOMAIN_MEMREGION_SU_EXECUTABLE) - pmp_flags |= PMP_X; + if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMEPMP)) { + pmp_flags = sbi_hart_get_smepmp_flags(scratch, dom, reg); + + if (pmp_flags == 0) + return 0; + } else { + /* + * If permissions are to be enforced for all modes on + * this region, the lock bit should be set. + */ + if (reg->flags & SBI_DOMAIN_MEMREGION_ENF_PERMISSIONS) + pmp_flags |= PMP_L; + + if (reg->flags & SBI_DOMAIN_MEMREGION_SU_READABLE) + pmp_flags |= PMP_R; + if (reg->flags & SBI_DOMAIN_MEMREGION_SU_WRITABLE) + pmp_flags |= PMP_W; + if (reg->flags & SBI_DOMAIN_MEMREGION_SU_EXECUTABLE) + pmp_flags |= PMP_X; + } pmp_addr = reg->base >> PMP_SHIFT; - if (pmp_gran_log2 <= reg->order && pmp_addr < pmp_addr_max) + if (pmp_gran_log2 <= reg->order && pmp_addr < pmp_addr_max) { pmp_set(pmp_idx++, pmp_flags, reg->base, reg->order); - else { - sbi_printf("Can not configure pmp for domain %s", dom->name); - sbi_printf(" because memory region address %lx or size %lx is not in range\n", - reg->base, reg->order); + } else { + sbi_printf("Can not configure pmp for domain %s because" + " memory region address 0x%lx or size 0x%lx " + "is not in range.\n", dom->name, reg->base, + reg->order); } } + if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMEPMP)) { + /* + * All entries are programmed. Enable MML bit. + * Keep the RLB bit so that dynamic mappings can be done. + */ + csr_set(CSR_MSECCFG, (MSECCFG_RLB | MSECCFG_MML)); + } + /* * As per section 3.7.2 of privileged specification v1.12, * virtual address translations can be speculatively performed |