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cjal{,r}: always seal return pointers #101

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cjal{,r}: always seal return pointers #101

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17 changes: 14 additions & 3 deletions src/cheri_cap_common.sail
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Original file line number Diff line number Diff line change
Expand Up @@ -614,16 +614,27 @@ function isCapForwardControlSentry(cap) =
}

/*!
* Returns true if the given capability has one of the backward sentry otypes, otherwise false.
* Returns true if the given capability has one of the IRQ-setting backward sentry otypes, otherwise false.
*/
val isCapBackwardSentry : Capability -> bool
function isCapBackwardSentry(cap) =
val isCapBackwardNoninheritingSentry : Capability -> bool
function isCapBackwardNoninheritingSentry(cap) =
match unsigned(cap.otype) {
otype if otype == otype_sentry_bid => true,
otype if otype == otype_sentry_bie => true,
_ => false
}

/*!
* Returns true iff the given capability is an IRQ-inheriting backward sentry.
*/
val isCapBackwardInheritingSentry : Capability -> bool
function isCapBackwardInheritingSentry(cap) =
match unsigned(cap.otype) {
otype if otype == otype_sentry_b => true,
_ => false
}


/*!
* Returns true if the given capability has one of the forward interrupt-inherited sentry otype, otherwise false.
*/
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16 changes: 10 additions & 6 deletions src/cheri_insts.sail
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Original file line number Diff line number Diff line change
Expand Up @@ -122,8 +122,8 @@ function clause execute(CJAL(imm, cd)) = {
let sentry_type = if mstatus.MIE() == 0b1 then otype_sentry_bie else otype_sentry_bid;
C(cd) = sealCap(linkCap, to_bits(cap_otype_width, sentry_type));
} else {
/* Generate an unsealed return capability. */
C(cd) = linkCap;
/* Generate an IRQ-inheriting return capability. */
C(cd) = sealCap(linkCap, to_bits(cap_otype_width, otype_sentry_b));
};

nextPC = newPC;
Expand Down Expand Up @@ -168,8 +168,11 @@ function clause execute(CJALR(imm, cs1, cd)) = {
handle_cheri_reg_exception(CapEx_TagViolation, cs1);
RETIRE_FAIL
} else if (isCapSealed(cs1_val) & imm != zeros()) |
not ((cd == zreg & cs1 == ra & isCapBackwardSentry(cs1_val)) |
(cd == zreg & cs1 != ra & (not(isCapSealed(cs1_val)) | isCapForwardInheritSentry(cs1_val))) |
not ((cd == zreg & cs1 == ra & isCapBackwardNoninheritingSentry(cs1_val)) |
(cd == zreg & cs1 != ra &
(not(isCapSealed(cs1_val)) |
isCapBackwardInheritingSentry(cs1_val) |
isCapForwardInheritSentry(cs1_val))) |
(cd != zreg & (not(isCapSealed(cs1_val)) | isCapForwardInheritSentry(cs1_val))) |
(cd == ra & (not(isCapSealed(cs1_val)) | isCapForwardSentry(cs1_val)))) then {
handle_cheri_reg_exception(CapEx_SealViolation, cs1);
Expand All @@ -195,9 +198,10 @@ function clause execute(CJALR(imm, cs1, cd)) = {
} else {
/*
* Generate an unsealed return capability. From the conditions above, it
* must be the case that cs1 is unsealed or a forward inheriting sentry.
* must be the case that cs1 is unsealed or an inheriting sentry (either
* forward or backward).
*/
C(cd) = linkCap;
C(cd) = sealCap(linkCap, to_bits(cap_otype_width, otype_sentry_b));
};

nextPC = newPC;
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1 change: 1 addition & 0 deletions src/cheri_types.sail
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Expand Up @@ -66,6 +66,7 @@ let otype_sentry_id = 2 /* sentry disabling interrupts */
let otype_sentry_ie = 3 /* sentry enabling interrupts */
let otype_sentry_bid = 4 /* backward sentry disabling interrupts */
let otype_sentry_bie = 5 /* backward sentry enabling interrupts */
let otype_sentry_b = 6 /* backward sentry inheriting */

enum CPtrCmpOp = {
CEQ,
Expand Down