diff options
Diffstat (limited to 'accel/tcg/user-exec.c')
| -rw-r--r-- | accel/tcg/user-exec.c | 58 |
1 files changed, 47 insertions, 11 deletions
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c index 492ea08..0324ba8 100644 --- a/accel/tcg/user-exec.c +++ b/accel/tcg/user-exec.c @@ -39,6 +39,8 @@ #include <sys/ucontext.h> #endif +__thread uintptr_t helper_retaddr; + //#define DEBUG_SIGNAL /* exit the current TB from a signal handler. The host registers are @@ -62,6 +64,27 @@ static inline int handle_cpu_signal(uintptr_t pc, unsigned long address, CPUClass *cc; int ret; + /* We must handle PC addresses from two different sources: + * a call return address and a signal frame address. + * + * Within cpu_restore_state_from_tb we assume the former and adjust + * the address by -GETPC_ADJ so that the address is within the call + * insn so that addr does not accidentally match the beginning of the + * next guest insn. + * + * However, when the PC comes from the signal frame, it points to + * the actual faulting host insn and not a call insn. Subtracting + * GETPC_ADJ in that case may accidentally match the previous guest insn. + * + * So for the later case, adjust forward to compensate for what + * will be done later by cpu_restore_state_from_tb. + */ + if (helper_retaddr) { + pc = helper_retaddr; + } else { + pc += GETPC_ADJ; + } + /* For synchronous signals we expect to be coming from the vCPU * thread (so current_cpu should be valid) and either from running * code or during translation which can fault as we cross pages. @@ -84,21 +107,24 @@ static inline int handle_cpu_signal(uintptr_t pc, unsigned long address, switch (page_unprotect(h2g(address), pc)) { case 0: /* Fault not caused by a page marked unwritable to protect - * cached translations, must be the guest binary's problem + * cached translations, must be the guest binary's problem. */ break; case 1: /* Fault caused by protection of cached translation; TBs - * invalidated, so resume execution + * invalidated, so resume execution. Retain helper_retaddr + * for a possible second fault. */ return 1; case 2: /* Fault caused by protection of cached translation, and the * currently executing TB was modified and must be exited - * immediately. + * immediately. Clear helper_retaddr for next execution. */ + helper_retaddr = 0; cpu_exit_tb_from_sighandler(cpu, old_set); - g_assert_not_reached(); + /* NORETURN */ + default: g_assert_not_reached(); } @@ -112,17 +138,25 @@ static inline int handle_cpu_signal(uintptr_t pc, unsigned long address, /* see if it is an MMU fault */ g_assert(cc->handle_mmu_fault); ret = cc->handle_mmu_fault(cpu, address, is_write, MMU_USER_IDX); + + if (ret == 0) { + /* The MMU fault was handled without causing real CPU fault. + * Retain helper_retaddr for a possible second fault. + */ + return 1; + } + + /* All other paths lead to cpu_exit; clear helper_retaddr + * for next execution. + */ + helper_retaddr = 0; + if (ret < 0) { return 0; /* not an MMU fault */ } - if (ret == 0) { - return 1; /* the MMU fault was handled without causing real CPU fault */ - } - /* Now we have a real cpu fault. Since this is the exact location of - * the exception, we must undo the adjustment done by cpu_restore_state - * for handling call return addresses. */ - cpu_restore_state(cpu, pc + GETPC_ADJ); + /* Now we have a real cpu fault. */ + cpu_restore_state(cpu, pc); sigprocmask(SIG_SETMASK, old_set, NULL); cpu_loop_exit(cpu); @@ -585,11 +619,13 @@ static void *atomic_mmu_lookup(CPUArchState *env, target_ulong addr, if (unlikely(addr & (size - 1))) { cpu_loop_exit_atomic(ENV_GET_CPU(env), retaddr); } + helper_retaddr = retaddr; return g2h(addr); } /* Macro to call the above, with local variables from the use context. */ #define ATOMIC_MMU_LOOKUP atomic_mmu_lookup(env, addr, DATA_SIZE, GETPC()) +#define ATOMIC_MMU_CLEANUP do { helper_retaddr = 0; } while (0) #define ATOMIC_NAME(X) HELPER(glue(glue(atomic_ ## X, SUFFIX), END)) #define EXTRA_ARGS |