Re: [PATCH v6 08/21] accel/tcg: Properly implement get_page_addr_code for user-only

[Alistair Francis]

On Fri, Aug 19, 2022 at 1:40 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> The current implementation is a no-op, simply returning addr.
> This is incorrect, because we ought to be checking the page
> permissions for execution.
>
> Make get_page_addr_code inline for both implementations.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  include/exec/exec-all.h | 85 ++++++++++++++---------------------------
>  accel/tcg/cputlb.c      |  5 ---
>  accel/tcg/user-exec.c   | 15 ++++++++
>  3 files changed, 43 insertions(+), 62 deletions(-)
>
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 311e5fb422..0475ec6007 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -598,43 +598,44 @@ struct MemoryRegionSection *iotlb_to_section(CPUState 
> *cpu,
>                                               hwaddr index, MemTxAttrs attrs);
>  #endif
>
> -#if defined(CONFIG_USER_ONLY)
> -void mmap_lock(void);
> -void mmap_unlock(void);
> -bool have_mmap_lock(void);
> -
>  /**
> - * get_page_addr_code() - user-mode version
> + * get_page_addr_code_hostp()
>   * @env: CPUArchState
>   * @addr: guest virtual address of guest code
>   *
> - * Returns @addr.
> + * See get_page_addr_code() (full-system version) for documentation on the
> + * return value.
> + *
> + * Sets *@hostp (when @hostp is non-NULL) as follows.
> + * If the return value is -1, sets *@hostp to NULL. Otherwise, sets *@hostp
> + * to the host address where @addr's content is kept.
> + *
> + * Note: this function can trigger an exception.
> + */
> +tb_page_addr_t get_page_addr_code_hostp(CPUArchState *env, target_ulong addr,
> +                                        void **hostp);
> +
> +/**
> + * get_page_addr_code()
> + * @env: CPUArchState
> + * @addr: guest virtual address of guest code
> + *
> + * If we cannot translate and execute from the entire RAM page, or if
> + * the region is not backed by RAM, returns -1. Otherwise, returns the
> + * ram_addr_t corresponding to the guest code at @addr.
> + *
> + * Note: this function can trigger an exception.
>   */
>  static inline tb_page_addr_t get_page_addr_code(CPUArchState *env,
>                                                  target_ulong addr)
>  {
> -    return addr;
> +    return get_page_addr_code_hostp(env, addr, NULL);
>  }
>
> -/**
> - * get_page_addr_code_hostp() - user-mode version
> - * @env: CPUArchState
> - * @addr: guest virtual address of guest code
> - *
> - * Returns @addr.
> - *
> - * If @hostp is non-NULL, sets *@hostp to the host address where @addr's 
> content
> - * is kept.
> - */
> -static inline tb_page_addr_t get_page_addr_code_hostp(CPUArchState *env,
> -                                                      target_ulong addr,
> -                                                      void **hostp)
> -{
> -    if (hostp) {
> -        *hostp = g2h_untagged(addr);
> -    }
> -    return addr;
> -}
> +#if defined(CONFIG_USER_ONLY)
> +void mmap_lock(void);
> +void mmap_unlock(void);
> +bool have_mmap_lock(void);
>
>  /**
>   * adjust_signal_pc:
> @@ -691,36 +692,6 @@ G_NORETURN void cpu_loop_exit_sigbus(CPUState *cpu, 
> target_ulong addr,
>  static inline void mmap_lock(void) {}
>  static inline void mmap_unlock(void) {}
>
> -/**
> - * get_page_addr_code() - full-system version
> - * @env: CPUArchState
> - * @addr: guest virtual address of guest code
> - *
> - * If we cannot translate and execute from the entire RAM page, or if
> - * the region is not backed by RAM, returns -1. Otherwise, returns the
> - * ram_addr_t corresponding to the guest code at @addr.
> - *
> - * Note: this function can trigger an exception.
> - */
> -tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr);
> -
> -/**
> - * get_page_addr_code_hostp() - full-system version
> - * @env: CPUArchState
> - * @addr: guest virtual address of guest code
> - *
> - * See get_page_addr_code() (full-system version) for documentation on the
> - * return value.
> - *
> - * Sets *@hostp (when @hostp is non-NULL) as follows.
> - * If the return value is -1, sets *@hostp to NULL. Otherwise, sets *@hostp
> - * to the host address where @addr's content is kept.
> - *
> - * Note: this function can trigger an exception.
> - */
> -tb_page_addr_t get_page_addr_code_hostp(CPUArchState *env, target_ulong addr,
> -                                        void **hostp);
> -
>  void tlb_reset_dirty(CPUState *cpu, ram_addr_t start1, ram_addr_t length);
>  void tlb_set_dirty(CPUState *cpu, target_ulong vaddr);
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index a46f3a654d..43bd65c973 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -1544,11 +1544,6 @@ tb_page_addr_t get_page_addr_code_hostp(CPUArchState 
> *env, target_ulong addr,
>      return qemu_ram_addr_from_host_nofail(p);
>  }
>
> -tb_page_addr_t get_page_addr_code(CPUArchState *env, target_ulong addr)
> -{
> -    return get_page_addr_code_hostp(env, addr, NULL);
> -}
> -
>  static void notdirty_write(CPUState *cpu, vaddr mem_vaddr, unsigned size,
>                             CPUIOTLBEntry *iotlbentry, uintptr_t retaddr)
>  {
> diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
> index 20ada5472b..a20234fb02 100644
> --- a/accel/tcg/user-exec.c
> +++ b/accel/tcg/user-exec.c
> @@ -199,6 +199,21 @@ void *probe_access(CPUArchState *env, target_ulong addr, 
> int size,
>      return size ? g2h(env_cpu(env), addr) : NULL;
>  }
>
> +tb_page_addr_t get_page_addr_code_hostp(CPUArchState *env, target_ulong addr,
> +                                        void **hostp)
> +{
> +    int flags;
> +
> +    flags = probe_access_internal(env, addr, 1, MMU_INST_FETCH, true, 0);
> +    if (unlikely(flags)) {
> +        return -1;
> +    }
> +    if (hostp) {
> +        *hostp = g2h_untagged(addr);
> +    }
> +    return addr;
> +}
> +
>  /* The softmmu versions of these helpers are in cputlb.c.  */
>
>  /*
> --
> 2.34.1
>
>