Re: [RFC v4 04/11] linux-user: Implement native-bypass option support

["Alex Bennée" <alex.bennee@linaro.org>]

Yeqi Fu <fufuyqqqqqq@gmail.com> writes:

> This commit implements the -native-bypass support in linux-user. The
> native_calls_enabled() function can be true only when the
> '-native-bypass' option is given.
>
> Signed-off-by: Yeqi Fu <fufuyqqqqqq@gmail.com>
> ---
>  include/native/native.h |  9 +++++++++
>  linux-user/main.c       | 38 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+)
>  create mode 100644 include/native/native.h
>
> diff --git a/include/native/native.h b/include/native/native.h
> new file mode 100644
> index 0000000000..62951fafb1
> --- /dev/null
> +++ b/include/native/native.h
> @@ -0,0 +1,9 @@
> +/*
> + * Check if the native bypass feature is enabled.
> + */
> +#if defined(CONFIG_USER_ONLY) && defined(CONFIG_NATIVE_CALL)
> +extern char *native_lib_path;
> +#define native_bypass_enabled() native_lib_path ? true : false
> +#else
> +#define native_bypass_enabled() false
> +#endif
> diff --git a/linux-user/main.c b/linux-user/main.c
> index dba67ffa36..86ea0191f7 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -60,6 +60,11 @@
>  #include "semihosting/semihost.h"
>  #endif
>  
> +#if defined(CONFIG_NATIVE_CALL)
> +#include "native/native.h"
> +char *native_lib_path;
> +#endif
> +
>  #ifndef AT_FLAGS_PRESERVE_ARGV0
>  #define AT_FLAGS_PRESERVE_ARGV0_BIT 0
>  #define AT_FLAGS_PRESERVE_ARGV0 (1 << AT_FLAGS_PRESERVE_ARGV0_BIT)
> @@ -293,6 +298,17 @@ static void handle_arg_set_env(const char *arg)
>      free(r);
>  }
>  
> +#if defined(CONFIG_NATIVE_CALL)
> +static void handle_arg_native_bypass(const char *arg)
> +{
> +    if (access(arg, F_OK) != 0) {
> +        fprintf(stderr, "native library %s does not exist\n", arg);
> +        exit(EXIT_FAILURE);
> +    }
> +    native_lib_path = strdup(arg);

Although we never free this the coding style states:

  Because of the memory management rules, you must use g_strdup/g_strndup
  instead of plain strdup/strndup.

We do still have a few legacy strdup's to eliminate from the code base
though.

> +}
> +#endif
> +
>  static void handle_arg_unset_env(const char *arg)
>  {
>      char *r, *p, *token;
> @@ -522,6 +538,10 @@ static const struct qemu_argument arg_table[] = {
>       "",           "Generate a /tmp/perf-${pid}.map file for perf"},
>      {"jitdump",    "QEMU_JITDUMP",     false, handle_arg_jitdump,
>       "",           "Generate a jit-${pid}.dump file for perf"},
> +#if defined(CONFIG_NATIVE_CALL)
> +    {"native-bypass", "QEMU_NATIVE_BYPASS", true, handle_arg_native_bypass,
> +     "",           "native bypass for library calls in user mode only."},
> +#endif

You can drop " in user mode only" because this help text will only show
up on linux-user binaries with support for native bypass.

Otherwise:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro