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qemu/target/arm/debug_helper.c

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/*
* ARM debug helpers.
*
* This code is licensed under the GNU GPL v2 or later.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "internals.h"
#include "exec/exec-all.h"
#include "exec/helper-proto.h"
/* Return true if the linked breakpoint entry lbn passes its checks */
static bool linked_bp_matches(ARMCPU *cpu, int lbn)
{
CPUARMState *env = &cpu->env;
uint64_t bcr = env->cp15.dbgbcr[lbn];
int brps = extract32(cpu->dbgdidr, 24, 4);
int ctx_cmps = extract32(cpu->dbgdidr, 20, 4);
int bt;
uint32_t contextidr;
uint64_t hcr_el2;
/*
* Links to unimplemented or non-context aware breakpoints are
* CONSTRAINED UNPREDICTABLE: either behave as if disabled, or
* as if linked to an UNKNOWN context-aware breakpoint (in which
* case DBGWCR<n>_EL1.LBN must indicate that breakpoint).
* We choose the former.
*/
if (lbn > brps || lbn < (brps - ctx_cmps)) {
return false;
}
bcr = env->cp15.dbgbcr[lbn];
if (extract64(bcr, 0, 1) == 0) {
/* Linked breakpoint disabled : generate no events */
return false;
}
bt = extract64(bcr, 20, 4);
hcr_el2 = arm_hcr_el2_eff(env);
switch (bt) {
case 3: /* linked context ID match */
switch (arm_current_el(env)) {
default:
/* Context matches never fire in AArch64 EL3 */
return false;
case 2:
if (!(hcr_el2 & HCR_E2H)) {
/* Context matches never fire in EL2 without E2H enabled. */
return false;
}
contextidr = env->cp15.contextidr_el[2];
break;
case 1:
contextidr = env->cp15.contextidr_el[1];
break;
case 0:
if ((hcr_el2 & (HCR_E2H | HCR_TGE)) == (HCR_E2H | HCR_TGE)) {
contextidr = env->cp15.contextidr_el[2];
} else {
contextidr = env->cp15.contextidr_el[1];
}
break;
}
break;
case 7: /* linked contextidr_el1 match */
contextidr = env->cp15.contextidr_el[1];
break;
case 13: /* linked contextidr_el2 match */
contextidr = env->cp15.contextidr_el[2];
break;
case 9: /* linked VMID match (reserved if no EL2) */
case 11: /* linked context ID and VMID match (reserved if no EL2) */
case 15: /* linked full context ID match */
default:
/*
* Links to Unlinked context breakpoints must generate no
* events; we choose to do the same for reserved values too.
*/
return false;
}
/*
* We match the whole register even if this is AArch32 using the
* short descriptor format (in which case it holds both PROCID and ASID),
* since we don't implement the optional v7 context ID masking.
*/
return contextidr == (uint32_t)env->cp15.dbgbvr[lbn];
}
static bool bp_wp_matches(ARMCPU *cpu, int n, bool is_wp)
{
CPUARMState *env = &cpu->env;
uint64_t cr;
int pac, hmc, ssc, wt, lbn;
/*
* Note that for watchpoints the check is against the CPU security
* state, not the S/NS attribute on the offending data access.
*/
bool is_secure = arm_is_secure(env);
int access_el = arm_current_el(env);
if (is_wp) {
CPUWatchpoint *wp = env->cpu_watchpoint[n];
if (!wp || !(wp->flags & BP_WATCHPOINT_HIT)) {
return false;
}
cr = env->cp15.dbgwcr[n];
if (wp->hitattrs.user) {
/*
* The LDRT/STRT/LDT/STT "unprivileged access" instructions should
* match watchpoints as if they were accesses done at EL0, even if
* the CPU is at EL1 or higher.
*/
access_el = 0;
}
} else {
uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
if (!env->cpu_breakpoint[n] || env->cpu_breakpoint[n]->pc != pc) {
return false;
}
cr = env->cp15.dbgbcr[n];
}
/*
* The WATCHPOINT_HIT flag guarantees us that the watchpoint is
* enabled and that the address and access type match; for breakpoints
* we know the address matched; check the remaining fields, including
* linked breakpoints. We rely on WCR and BCR having the same layout
* for the LBN, SSC, HMC, PAC/PMC and is-linked fields.
* Note that some combinations of {PAC, HMC, SSC} are reserved and
* must act either like some valid combination or as if the watchpoint
* were disabled. We choose the former, and use this together with
* the fact that EL3 must always be Secure and EL2 must always be
* Non-Secure to simplify the code slightly compared to the full
* table in the ARM ARM.
*/
pac = extract64(cr, 1, 2);
hmc = extract64(cr, 13, 1);
ssc = extract64(cr, 14, 2);
switch (ssc) {
case 0:
break;
case 1:
case 3:
if (is_secure) {
return false;
}
break;
case 2:
if (!is_secure) {
return false;
}
break;
}
switch (access_el) {
case 3:
case 2:
if (!hmc) {
return false;
}
break;
case 1:
if (extract32(pac, 0, 1) == 0) {
return false;
}
break;
case 0:
if (extract32(pac, 1, 1) == 0) {
return false;
}
break;
default:
g_assert_not_reached();
}
wt = extract64(cr, 20, 1);
lbn = extract64(cr, 16, 4);
if (wt && !linked_bp_matches(cpu, lbn)) {
return false;
}
return true;
}
static bool check_watchpoints(ARMCPU *cpu)
{
CPUARMState *env = &cpu->env;
int n;
/*
* If watchpoints are disabled globally or we can't take debug
* exceptions here then watchpoint firings are ignored.
*/
if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
|| !arm_generate_debug_exceptions(env)) {
return false;
}
for (n = 0; n < ARRAY_SIZE(env->cpu_watchpoint); n++) {
if (bp_wp_matches(cpu, n, true)) {
return true;
}
}
return false;
}
static bool check_breakpoints(ARMCPU *cpu)
{
CPUARMState *env = &cpu->env;
int n;
/*
* If breakpoints are disabled globally or we can't take debug
* exceptions here then breakpoint firings are ignored.
*/
if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
|| !arm_generate_debug_exceptions(env)) {
return false;
}
for (n = 0; n < ARRAY_SIZE(env->cpu_breakpoint); n++) {
if (bp_wp_matches(cpu, n, false)) {
return true;
}
}
return false;
}
void HELPER(check_breakpoints)(CPUARMState *env)
{
ARMCPU *cpu = env_archcpu(env);
if (check_breakpoints(cpu)) {
HELPER(exception_internal(env, EXCP_DEBUG));
}
}
bool arm_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp)
{
/*
* Called by core code when a CPU watchpoint fires; need to check if this
* is also an architectural watchpoint match.
*/
ARMCPU *cpu = ARM_CPU(cs);
return check_watchpoints(cpu);
}
void arm_debug_excp_handler(CPUState *cs)
{
/*
* Called by core code when a watchpoint or breakpoint fires;
* need to check which one and raise the appropriate exception.
*/
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
CPUWatchpoint *wp_hit = cs->watchpoint_hit;
if (wp_hit) {
if (wp_hit->flags & BP_CPU) {
bool wnr = (wp_hit->flags & BP_WATCHPOINT_HIT_WRITE) != 0;
bool same_el = arm_debug_target_el(env) == arm_current_el(env);
cs->watchpoint_hit = NULL;
env->exception.fsr = arm_debug_exception_fsr(env);
env->exception.vaddress = wp_hit->hitaddr;
raise_exception(env, EXCP_DATA_ABORT,
syn_watchpoint(same_el, 0, wnr),
arm_debug_target_el(env));
}
} else {
uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
bool same_el = (arm_debug_target_el(env) == arm_current_el(env));
/*
* (1) GDB breakpoints should be handled first.
* (2) Do not raise a CPU exception if no CPU breakpoint has fired,
* since singlestep is also done by generating a debug internal
* exception.
*/
if (cpu_breakpoint_test(cs, pc, BP_GDB)
|| !cpu_breakpoint_test(cs, pc, BP_CPU)) {
return;
}
env->exception.fsr = arm_debug_exception_fsr(env);
/*
* FAR is UNKNOWN: clear vaddress to avoid potentially exposing
* values to the guest that it shouldn't be able to see at its
* exception/security level.
*/
env->exception.vaddress = 0;
raise_exception(env, EXCP_PREFETCH_ABORT,
syn_breakpoint(same_el),
arm_debug_target_el(env));
}
}
#if !defined(CONFIG_USER_ONLY)
vaddr arm_adjust_watchpoint_address(CPUState *cs, vaddr addr, int len)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
/*
* In BE32 system mode, target memory is stored byteswapped (on a
* little-endian host system), and by the time we reach here (via an
* opcode helper) the addresses of subword accesses have been adjusted
* to account for that, which means that watchpoints will not match.
* Undo the adjustment here.
*/
if (arm_sctlr_b(env)) {
if (len == 1) {
addr ^= 3;
} else if (len == 2) {
addr ^= 2;
}
}
return addr;
}
#endif
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