On 16/05/16 19:09, Peter Maydell wrote:
> Since the only caller of page_unprotect() which might cause it to
> need to call cpu_resume_from_signal() is handle_cpu_signal() in
> the user-mode code, push the longjump handling out to that function.
>
> Since this is the only caller of cpu_resume_from_signal() which
> passes a non-NULL puc argument, split the non-NULL handling into
> a new cpu_exit_tb_from_sighandler() function. This allows us
> to merge the softmmu and usermode implementations of the
> cpu_resume_from_signal() function, which are now identical.
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Sergey Fedorov <sergey.fedo...@linaro.org>
> ---
> cpu-exec-common.c | 2 +-
> translate-all.c | 12 ++++++++----
> translate-all.h | 2 +-
> user-exec.c | 41 +++++++++++++++++++++++++++++------------
> 4 files changed, 39 insertions(+), 18 deletions(-)
>
> diff --git a/cpu-exec-common.c b/cpu-exec-common.c
> index 6bdda6b..62f5d6b 100644
> --- a/cpu-exec-common.c
> +++ b/cpu-exec-common.c
> @@ -28,7 +28,6 @@ CPUState *tcg_current_cpu;
> /* exit the current TB from a signal handler. The host registers are
> restored in a state compatible with the CPU emulator
> */
> -#if defined(CONFIG_SOFTMMU)
> void cpu_resume_from_signal(CPUState *cpu, void *puc)
> {
> /* XXX: restore cpu registers saved in host registers */
> @@ -37,6 +36,7 @@ void cpu_resume_from_signal(CPUState *cpu, void *puc)
> siglongjmp(cpu->jmp_env, 1);
> }
>
> +#if defined(CONFIG_SOFTMMU)
> void cpu_reloading_memory_map(void)
> {
> if (qemu_in_vcpu_thread()) {
> diff --git a/translate-all.c b/translate-all.c
> index 4820d2e..52a571e 100644
> --- a/translate-all.c
> +++ b/translate-all.c
> @@ -1955,7 +1955,7 @@ int page_check_range(target_ulong start, target_ulong
> len, int flags)
> /* unprotect the page if it was put read-only because it
> contains translated code */
> if (!(p->flags & PAGE_WRITE)) {
> - if (!page_unprotect(addr, 0, NULL)) {
> + if (!page_unprotect(addr, 0)) {
> return -1;
> }
> }
> @@ -1965,8 +1965,12 @@ int page_check_range(target_ulong start, target_ulong
> len, int flags)
> }
>
> /* called from signal handler: invalidate the code and unprotect the
> - page. Return TRUE if the fault was successfully handled. */
> -int page_unprotect(target_ulong address, uintptr_t pc, void *puc)
> + * page. Return 0 if the fault was not handled, 1 if it was handled,
> + * and 2 if it was handled but the caller must cause the TB to be
> + * immediately exited. (We can only return 2 if the 'pc' argument is
> + * non-zero.)
> + */
> +int page_unprotect(target_ulong address, uintptr_t pc)
> {
> unsigned int prot;
> PageDesc *p;
> @@ -1999,7 +2003,7 @@ int page_unprotect(target_ulong address, uintptr_t pc,
> void *puc)
> the corresponding translated code. */
> if (tb_invalidate_phys_page(addr, pc)) {
> mmap_unlock();
> - cpu_resume_from_signal(current_cpu, puc);
> + return 2;
> }
> #ifdef DEBUG_TB_CHECK
> tb_invalidate_check(addr);
> diff --git a/translate-all.h b/translate-all.h
> index 0384640..ce6071b 100644
> --- a/translate-all.h
> +++ b/translate-all.h
> @@ -27,7 +27,7 @@ void tb_invalidate_phys_range(tb_page_addr_t start,
> tb_page_addr_t end);
> void tb_check_watchpoint(CPUState *cpu);
>
> #ifdef CONFIG_USER_ONLY
> -int page_unprotect(target_ulong address, uintptr_t pc, void *puc);
> +int page_unprotect(target_ulong address, uintptr_t pc);
> #endif
>
> #endif /* TRANSLATE_ALL_H */
> diff --git a/user-exec.c b/user-exec.c
> index d8d597b..1d02e24 100644
> --- a/user-exec.c
> +++ b/user-exec.c
> @@ -54,7 +54,7 @@ static void exception_action(CPUState *cpu)
> /* exit the current TB from a signal handler. The host registers are
> restored in a state compatible with the CPU emulator
> */
> -void cpu_resume_from_signal(CPUState *cpu, void *puc)
> +static void cpu_exit_tb_from_sighandler(CPUState *cpu, void *puc)
> {
> #ifdef __linux__
> struct ucontext *uc = puc;
> @@ -62,20 +62,18 @@ void cpu_resume_from_signal(CPUState *cpu, void *puc)
> struct sigcontext *uc = puc;
> #endif
>
> - if (puc) {
> - /* XXX: use siglongjmp ? */
> + /* XXX: use siglongjmp ? */
> #ifdef __linux__
> #ifdef __ia64
> - sigprocmask(SIG_SETMASK, (sigset_t *)&uc->uc_sigmask, NULL);
> + sigprocmask(SIG_SETMASK, (sigset_t *)&uc->uc_sigmask, NULL);
> #else
> - sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
> + sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
> #endif
> #elif defined(__OpenBSD__)
> - sigprocmask(SIG_SETMASK, &uc->sc_mask, NULL);
> + sigprocmask(SIG_SETMASK, &uc->sc_mask, NULL);
> #endif
> - }
> - cpu->exception_index = -1;
> - siglongjmp(cpu->jmp_env, 1);
> +
> + cpu_resume_from_signal(cpu, NULL);
> }
>
> /* 'pc' is the host PC at which the exception was raised. 'address' is
> @@ -95,9 +93,28 @@ static inline int handle_cpu_signal(uintptr_t pc, unsigned
> long address,
> pc, address, is_write, *(unsigned long *)old_set);
> #endif
> /* XXX: locking issue */
> - if (is_write && h2g_valid(address)
> - && page_unprotect(h2g(address), pc, puc)) {
> - return 1;
> + if (is_write && h2g_valid(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
> + */
> + break;
> + case 1:
> + /* Fault caused by protection of cached translation; TBs
> + * invalidated, so resume execution
> + */
> + return 1;
> + case 2:
> + /* Fault caused by protection of cached translation, and the
> + * currently executing TB was modified and must be exited
> + * immediately.
> + */
> + cpu_exit_tb_from_sighandler(current_cpu, puc);
> + g_assert_not_reached();
> + default:
> + g_assert_not_reached();
> + }
> }
>
> /* Convert forcefully to guest address space, invalid addresses
