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target-arm: correct CNTFRQ access rights

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Correct some corner cases we were getting wrong for
CNTFRQ access rights:
* should UNDEF from 32-bit Secure EL1
* only writable from the highest implemented exception level,
which might not be EL1 now

To clarify the code, provide a new utility function
arm_highest_el() which returns the highest implemented
exception level.

Backports commit 755026728abb19fba70e6b4396a27fa2e7550d74 from qemu
This commit is contained in:
Peter Maydell 2018-02-20 14:49:02 -05:00 committed by Lioncash
parent 22d4f95912
commit 7b503db3c6
No known key found for this signature in database
GPG key ID: 4E3C3CC1031BA9C7
2 changed files with 38 additions and 3 deletions
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12
qemu/target-arm/cpu.h
View file

@ -1268,6 +1268,18 @@ static inline bool cptype_valid(int cptype)
#define PL1_RW (PL1_R | PL1_W)
#define PL0_RW (PL0_R | PL0_W)
/* Return the highest implemented Exception Level */
static inline int arm_highest_el(CPUARMState *env)
{
if (arm_feature(env, ARM_FEATURE_EL3)) {
return 3;
}
if (arm_feature(env, ARM_FEATURE_EL2)) {
return 2;
}
return 1;
}
/* Return the current Exception Level (as per ARMv8; note that this differs
* from the ARMv7 Privilege Level).
*/

29
qemu/target-arm/helper.c
View file

@ -1061,10 +1061,33 @@ static const ARMCPRegInfo v6k_cp_reginfo[] = {
static CPAccessResult gt_cntfrq_access(CPUARMState *env, const ARMCPRegInfo *ri,
bool isread)
{
/* CNTFRQ: not visible from PL0 if both PL0PCTEN and PL0VCTEN are zero */
if (arm_current_el(env) == 0 && !extract32(env->cp15.c14_cntkctl, 0, 2)) {
return CP_ACCESS_TRAP;
/* CNTFRQ: not visible from PL0 if both PL0PCTEN and PL0VCTEN are zero.
* Writable only at the highest implemented exception level.
*/
int el = arm_current_el(env);
switch (el) {
case 0:
if (!extract32(env->cp15.c14_cntkctl, 0, 2)) {
return CP_ACCESS_TRAP;
}
break;
case 1:
if (!isread && ri->state == ARM_CP_STATE_AA32 &&
arm_is_secure_below_el3(env)) {
/* Accesses from 32-bit Secure EL1 UNDEF (*not* trap to EL3!) */
return CP_ACCESS_TRAP_UNCATEGORIZED;
}
break;
case 2:
case 3:
break;
}
if (!isread && el < arm_highest_el(env)) {
return CP_ACCESS_TRAP_UNCATEGORIZED;
}
return CP_ACCESS_OK;
}