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target/arm: Support CP_ACCESS_TRAP_EL1 as a CPAccessResult

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In the CPAccessResult enum, the CP_ACCESS_TRAP* values indicate the
equivalent of the pseudocode AArch64.SystemAccessTrap(..., 0x18),
causing a trap to a specified exception level with a syndrome value
giving information about the failing instructions.  In the
pseudocode, such traps are always taken to a specified target EL.  We
support that for target EL of 2 or 3 via CP_ACCESS_TRAP_EL2 and
CP_ACCESS_TRAP_EL3, but the only way to take the access trap to EL1
currently is to use CP_ACCESS_TRAP, which takes the trap to the
"usual target EL" (EL1 if in EL0, otherwise to the current EL).

Add CP_ACCESS_TRAP_EL1 so that access functions can follow the
pseudocode more closely.

(Note that for the common case in the pseudocode of "trap to
EL2 if HCR_EL2.TGE is set, otherwise trap to EL1", we handle
this in raise_exception(), so access functions don't need to
special case it and can use CP_ACCESS_TRAP_EL1.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250130182309.717346-10-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2025-01-30 18:23:04 +00:00
parent ff8b906a00
commit 273d0e84cc
2 changed files with 5 additions and 2 deletions
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1
target/arm/cpregs.h
View File

@ -331,6 +331,7 @@ typedef enum CPAccessResult {
* 0xc or 0x18).
*/
CP_ACCESS_TRAP = (1 << 2),
CP_ACCESS_TRAP_EL1 = CP_ACCESS_TRAP | 1,
CP_ACCESS_TRAP_EL2 = CP_ACCESS_TRAP | 2,
CP_ACCESS_TRAP_EL3 = CP_ACCESS_TRAP | 3,

6
target/arm/tcg/op_helper.c
View File

@ -781,7 +781,7 @@ const void *HELPER(access_check_cp_reg)(CPUARMState *env, uint32_t key,
* the other trap takes priority. So we take the "check HSTR_EL2" path
* for all of those cases.)
*/
if (res != CP_ACCESS_OK && ((res & CP_ACCESS_EL_MASK) == 0) &&
if (res != CP_ACCESS_OK && ((res & CP_ACCESS_EL_MASK) < 2) &&
arm_current_el(env) == 0) {
goto fail;
}
@ -887,6 +887,9 @@ const void *HELPER(access_check_cp_reg)(CPUARMState *env, uint32_t key,
case 0:
target_el = exception_target_el(env);
break;
case 1:
assert(arm_current_el(env) < 2);
break;
case 2:
assert(arm_current_el(env) != 3);
assert(arm_is_el2_enabled(env));
@ -895,7 +898,6 @@ const void *HELPER(access_check_cp_reg)(CPUARMState *env, uint32_t key,
assert(arm_feature(env, ARM_FEATURE_EL3));
break;
default:
/* No "direct" traps to EL1 */
g_assert_not_reached();
}