On Thu, Oct 14, 2021 at 10:10 PM Richard Henderson <
richard.henderson@linaro.org> wrote:
> Split out a function to adjust the raw signal pc into a
> value that could be passed to cpu_restore_state.
>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> v2: Adjust pc in place; return MMUAccessType.
> ---
> include/exec/exec-all.h | 10 ++++++++++
> accel/tcg/user-exec.c | 41 +++++++++++++++++++++++++----------------
> 2 files changed, 35 insertions(+), 16 deletions(-)
>
Reviewed-by: Warner Losh <imp@bsdimp.com>
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 9d5987ba04..e54f8e5d65 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -663,6 +663,16 @@ static inline tb_page_addr_t
> get_page_addr_code_hostp(CPUArchState *env,
> return addr;
> }
>
> +/**
> + * adjust_signal_pc:
> + * @pc: raw pc from the host signal ucontext_t.
> + * @is_write: host memory operation was write, or read-modify-write.
> + *
> + * Alter @pc as required for unwinding. Return the type of the
> + * guest memory access -- host reads may be for guest execution.
> + */
> +MMUAccessType adjust_signal_pc(uintptr_t *pc, bool is_write);
> +
> /**
> * cpu_signal_handler
> * @signum: host signal number
> diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
> index e6bb29b42d..c02d509ec6 100644
> --- a/accel/tcg/user-exec.c
> +++ b/accel/tcg/user-exec.c
> @@ -57,18 +57,11 @@ static void QEMU_NORETURN
> cpu_exit_tb_from_sighandler(CPUState *cpu,
> cpu_loop_exit_noexc(cpu);
> }
>
> -/* 'pc' is the host PC at which the exception was raised. 'address' is
> - the effective address of the memory exception. 'is_write' is 1 if a
> - write caused the exception and otherwise 0'. 'old_set' is the
> - signal set which should be restored */
> -static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
> - int is_write, sigset_t *old_set)
> +/*
> + * Adjust the pc to pass to cpu_restore_state; return the memop type.
> + */
> +MMUAccessType adjust_signal_pc(uintptr_t *pc, bool is_write)
> {
> - CPUState *cpu = current_cpu;
> - CPUClass *cc;
> - unsigned long address = (unsigned long)info->si_addr;
> - MMUAccessType access_type = is_write ? MMU_DATA_STORE : MMU_DATA_LOAD;
> -
> switch (helper_retaddr) {
> default:
> /*
> @@ -77,7 +70,7 @@ static inline int handle_cpu_signal(uintptr_t pc,
> siginfo_t *info,
> * pointer into the generated code that will unwind to the
> * correct guest pc.
> */
> - pc = helper_retaddr;
> + *pc = helper_retaddr;
> break;
>
> case 0:
> @@ -97,7 +90,7 @@ static inline int handle_cpu_signal(uintptr_t pc,
> siginfo_t *info,
> * Therefore, adjust to compensate for what will be done later
> * by cpu_restore_state_from_tb.
> */
> - pc += GETPC_ADJ;
> + *pc += GETPC_ADJ;
> break;
>
> case 1:
> @@ -113,12 +106,28 @@ static inline int handle_cpu_signal(uintptr_t pc,
> siginfo_t *info,
> *
> * Like tb_gen_code, release the memory lock before cpu_loop_exit.
> */
> - pc = 0;
> - access_type = MMU_INST_FETCH;
> mmap_unlock();
> - break;
> + *pc = 0;
> + return MMU_INST_FETCH;
> }
>
> + return is_write ? MMU_DATA_STORE : MMU_DATA_LOAD;
> +}
> +
> +/*
> + * 'pc' is the host PC at which the exception was raised.
> + * 'address' is the effective address of the memory exception.
> + * 'is_write' is 1 if a write caused the exception and otherwise 0.
> + * 'old_set' is the signal set which should be restored.
> + */
> +static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
> + int is_write, sigset_t *old_set)
> +{
> + CPUState *cpu = current_cpu;
> + CPUClass *cc;
> + unsigned long address = (unsigned long)info->si_addr;
> + MMUAccessType access_type = adjust_signal_pc(&pc, is_write);
> +
> /* 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.
> --
> 2.25.1
>
>