From 3d77127dcc69a53638b560cc1d5b6ead7c360f27 Mon Sep 17 00:00:00 2001 From: Stefan O'Rear Date: Thu, 25 Jan 2024 19:34:22 -0500 Subject: [PATCH] Minor fixes The exception table for CMOs comes from CTSRD-CHERI/cheri-specification#65. --- src/insns/cgetlen_32bit.adoc | 3 +- src/insns/cjalr_jalr_32bit.adoc | 5 ++-- src/riscv-integration.adoc | 52 ++++++++++++++++++++------------- 3 files changed, 36 insertions(+), 24 deletions(-) diff --git a/src/insns/cgetlen_32bit.adoc b/src/insns/cgetlen_32bit.adoc index 5ddf29d8..4fe083af 100644 --- a/src/insns/cgetlen_32bit.adoc +++ b/src/insns/cgetlen_32bit.adoc @@ -19,7 +19,8 @@ Calculate the length of `cs1` 's bounds and write the result in `rd`. The length is defined as the difference between the decoded bounds' top and base addresses i.e. `top - base`. It is not required that the input capability `cs1` has its tag set to 1. <> outputs 0 if `cs1` 's bounds are malformed (see -xref:section_cap_malformed[xrefstyle=short]). +xref:section_cap_malformed[xrefstyle=short]), and 2^XLENMAX^-1 if the length of +`cs1` is 2^XLENMAX^. Prerequisites:: {cheri_base_ext_name} diff --git a/src/insns/cjalr_jalr_32bit.adoc b/src/insns/cjalr_jalr_32bit.adoc index 88f52ec6..83f3b3ac 100644 --- a/src/insns/cjalr_jalr_32bit.adoc +++ b/src/insns/cjalr_jalr_32bit.adoc @@ -32,8 +32,9 @@ include::wavedrom/ct-unconditional-2.adoc[] Capability Mode Description:: CJALR allows unconditional, indirect jumps to a target capability. The -target capability is obtained by unsealing `cs1` and incrementing its address by the -sign-extended 12-bit immediate, and then setting the least-significant bit of the +target capability is obtained by unsealing `cs1` if the immediate is zero and +incrementing its address by the sign-extended 12-bit immediate otherwise, +and then setting the least-significant bit of the result to zero. The target capability may have xref:section_invalid_addr_conv[xrefstyle=short] performed and is then installed in <>. The <> diff --git a/src/riscv-integration.adoc b/src/riscv-integration.adoc index bd919499..d02866d6 100644 --- a/src/riscv-integration.adoc +++ b/src/riscv-integration.adoc @@ -86,7 +86,7 @@ tag is set and 0 otherwise permission fields of the input capability * <>: outputs the expanded base address of the input capability * <>: outputs the length of the input capability. Length is defined as -`top - base`. The output is 2^XLEN^-1 when the capability's length is +`top - base`. The output is 2^XLENMAX^-1 when the capability's length is 2^XLENMAX^ * <>: outputs the nearest bounds alignment that a valid capability can represent @@ -243,9 +243,10 @@ The capability jump and link register (<>) instruction replaces the jump and link register (<>) instruction at the same encoding. This instruction allows unconditional jumps to a target capability. The target capability is obtained by incrementing the capability in the *c* register operand by the -sign-extended 12-bit immediate, then setting the least significant bit of the -result to zero. The capability with the address of the instruction following -the jump (<> + 4) is written to a *c* register. +sign-extended 12-bit immediate if the immediate is not zero, then setting the +least significant bit of the result to zero, then unsealing. The capability +with the address of the instruction following the jump (<> + 4) is sealed +and written to a *c* register. All jumps cause CHERI exceptions when a minimum sized instruction at the target address is not within the bounds of the <>. @@ -253,6 +254,7 @@ at the target address is not within the bounds of the <>. <> causes a CHERI exception when: * The target capability's tag is zero +* The target capability is sealed and the immediate is not zero * A minimum sized instruction at the target capability's address is not within bounds * The target capability does not grant execute permission @@ -1020,7 +1022,7 @@ xref:mtval-cheri-causes[xrefstyle=short] respectively. === Unprivileged CSRs Unlike machine and supervisor level CSRs, {cheri_base_ext_name} does not require -<> to grant <> to access privileged CSRs. +<> to grant <> to access unprivileged CSRs. [#pcc,reftext="pcc"] ==== Program Counter Capability (pcc) @@ -1057,12 +1059,12 @@ NOTE: `auth_cap` is <> for Legacy mode and `cs1` for Capability Mode 6+| *CSR/Xret additional exception check* | CSR*, <>, <> | {cheri_excep_mcause} | {cheri_excep_type_pcc} | {cheri_excep_cause_perm} | <> permission | not(<>.<>) when required for CSR access or execution of <>/<> 6+| *direct jumps additional exception check* -| <>, <>, <> | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_length} | <> length | any byte of 16-bit instruction at target out of <> bounds -6+| *indirect jumps and conditional branches additional exception checks* -| indirect jumps and conditional branches | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_tag} |`cs1` tag | not(`cs1.tag`) -| indirect jumps and conditional branches | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_seal} |`cs1` seal | isCapSealed(`cs1`) -| indirect jumps and conditional branches | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_perm} |`cs1` permission| not(`cs1`.<>) -| indirect jumps and conditional branches | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_length} |`cs1` length | any byte of 16-bit instruction at target out of `cs1` bounds +| <>, <>, <> | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_length} | <> length | any byte of minimum length instruction at target out of <> bounds +6+| *indirect jumps additional exception checks* +| indirect jumps | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_tag} |`cs1` tag | not(`cs1.tag`) +| indirect jumps | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_seal} |`cs1` seal | isCapSealed(`cs1`) and imm12 != 0 +| indirect jumps | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_perm} |`cs1` permission| not(`cs1`.<>) +| indirect jumps | {cheri_excep_mcause} | {cheri_excep_type_jump} | {cheri_excep_cause_length} |`cs1` length | any byte of minimum length instruction at target out of `cs1` bounds 6+| *Load additional exception checks* | all loads | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_tag} | `auth_cap` tag | not(`auth_cap.tag`) | all loads | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_seal} | `auth_cap` seal | isCapSealed(`auth_cap`) @@ -1070,19 +1072,26 @@ NOTE: `auth_cap` is <> for Legacy mode and `cs1` for Capability Mode | all loads | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_length} | `auth_cap` length | Any byte of load access out of `auth_cap` bounds | capability loads | 4 | N/A | N/A | load address misaligned | Misaligned capability load 6+| *Store/atomic/cache-block-operation additional exception checks* -| all stores, all atomics, all cbos | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_tag} |`auth_cap` tag | not(`auth_cap.tag`) -| all stores, all atomics, all cbos | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_seal} |`auth_cap` seal | isCapSealed(`auth_cap`) -| all atomics, all cbos | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_perm} |`auth_cap` permission | AMO only: not(`auth_cap`.<>) -| all stores, all atomics, all cbos | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_perm} |`auth_cap` permission | not(auto_cap.<>) -| all stores, all atomics | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_length} |`auth_cap` length | any byte of access^1^ out of `auth_cap` bounds -| capability stores, all atomics |6 | N/A | N/A |Misaligned store/AMO| Misaligned capability store or AMO +| all stores, all atomics, all cbos | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_tag} |`auth_cap` tag | not(`auth_cap.tag`) +| all stores, all atomics, all cbos | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_seal} |`auth_cap` seal | isCapSealed(`auth_cap`) +| all atomics, CBO.INVAL* | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_perm} |`auth_cap` permission | not(`auth_cap`.<>) +| all stores, all atomics, CBO.INVAL*, CBO.ZERO* | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_perm} |`auth_cap` permission | not(`auth_cap`.<>) +| CBO.CLEAN*, CBO.FLUSH* | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_perm} |`auth_cap` permission | not(`auth_cap`.<>) and not(`auth_cap`.<>) +| all stores, all atomics | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_length} |`auth_cap` length | any byte of access out of `auth_cap` bounds +| CBO.ZERO*, CBO.INVAL* | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_length} |`auth_cap` length | any byte of cache block out of `auth_cap` bounds +| CBO.CLEAN*, CBO.FLUSH* | {cheri_excep_mcause} | {cheri_excep_type_data} | {cheri_excep_cause_length} |`auth_cap` length | all bytes of cache block out of `auth_cap` bounds +| CBO.INVAL* | {cheri_excep_mcause} | {cheri_excep_type_pcc} | {cheri_excep_cause_perm} |<> permission | not(<>.<>) +| capability stores | 6 | N/A | N/A |capability alignment | Misaligned capability store |========================================================================================= NOTE: Indirect branches are <>, <>, <>, <>, conditional branches are <>. -NOTE: <>, <> issues as a cache line wide store - -NOTE: ^1^Other CBOs (<>, <>, <>, <>, <>, <>) require at least one byte of the access to be in `auth_cap` bounds +NOTE: <>, <> issues as a cache block wide store. All +CMOs operate on the cache block which contains the address. Prefetches check +that the capability is tagged, not sealed, has the permission (<>, +<>, <>) corresponding to the instruction, and has bounds which +include at least one byte of the cache block; if any check fails, the prefetch +is not performed but no exception is generated. [#CHERI_SPEC,reftext="CHERI Exceptions and speculative execution"] === CHERI Exceptions and speculative execution @@ -1098,7 +1107,8 @@ is desirable that harts supporting {cheri_base_ext_name} extend PMAs with a _taggable_ attribute indicating whether a memory region allows storing tagged data. -When the hart attempts to store or load data with the tag set to memory regions +Data loaded from memory regions that are not taggable will always have the tag +cleared. When the hart attempts to store data with the tag set to memory regions that are not taggable, the implementation may: * Cause an access fault exception