Re: [Qemu-devel] [PATCH] /proc/self/maps content is not correct for a guest

[Mikhail Ilin <m.ilin@samsung.com>]

ping

http://patchwork.ozlabs.org/patch/374162/

On 28.07.2014 16:02, Mikhail Ilin wrote:
> Hi,
>
> As it was posted earlier the output of reading /proc/self/maps is not
> correct for a guest. There are some issues:
>
> https://bugs.launchpad.net/qemu/+bug/1346784
> http://lists.nongnu.org/archive/html/qemu-devel/2014-07/msg03085.html
> http://lists.nongnu.org/archive/html/qemu-devel/2014-07/msg02793.html
>
> The patch proposes: build /proc/self/maps doing a match against guest
> memory
> translation table and output only that map records which are valid for
> guest
> memory layout.
>
> Patches in mentioned threads are not relevant and are covered by the
> current
> patch.
>
> We did some local tests for i386, x86_64 and arm targets. The approach
> seems correct.
>
>
>  From 8479d3dd00194975d7016eeecba13ddf453e9647 Mon Sep 17 00:00:00 2001
> From: Mikhail Ilyin <m.ilin@samsung.com>
> Date: Mon, 28 Jul 2014 15:40:31 +0400
> Subject: [PATCH] Build /proc/self/maps doing a match against guest memory
>   translation table. Output only that map records which are valid for guest
>   memory layout.
>
> Signed-off-by: Mikhail Ilyin <m.ilin@samsung.com>
> ---
>   include/exec/cpu-all.h |  2 ++
>   linux-user/syscall.c   | 25 ++++++++++---------------
>   2 files changed, 12 insertions(+), 15 deletions(-)
>
> diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
> index f91581f..f9d132f 100644
> --- a/include/exec/cpu-all.h
> +++ b/include/exec/cpu-all.h
> @@ -198,6 +198,8 @@ extern unsigned long reserved_va;
>   #define RESERVED_VA 0ul
>   #endif
>
> +#define GUEST_ADDR_MAX (RESERVED_VA ? RESERVED_VA : \
> +                                    (1ul <<
> TARGET_VIRT_ADDR_SPACE_BITS) - 1)
>   #endif
>
>   /* page related stuff */
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index a50229d..189a8c0 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -5092,10 +5092,8 @@ static int open_self_cmdline(void *cpu_env, int fd)
>
>   static int open_self_maps(void *cpu_env, int fd)
>   {
> -#if defined(TARGET_ARM) || defined(TARGET_M68K) ||
> defined(TARGET_UNICORE32)
>       CPUState *cpu = ENV_GET_CPU((CPUArchState *)cpu_env);
>       TaskState *ts = cpu->opaque;
> -#endif
>       FILE *fp;
>       char *line = NULL;
>       size_t len = 0;
> @@ -5118,13 +5116,18 @@ static int open_self_maps(void *cpu_env, int fd)
>           if ((fields < 10) || (fields > 11)) {
>               continue;
>           }
> -        if (!strncmp(path, "[stack]", 7)) {
> -            continue;
> -        }
> -        if (h2g_valid(min) && h2g_valid(max)) {
> +        if (h2g_valid(min)) {
> +            int flags = page_get_flags(h2g(min));
> +            max = h2g_valid(max - 1) ? max :
> (uint64_t)g2h(GUEST_ADDR_MAX);
> +            if (page_check_range(h2g(min), max - min, flags) == -1) {
> +                continue;
> +            }
> +            if (h2g(min) == ts->info->stack_limit) {
> +                pstrcpy(path, sizeof(path), "      [stack]");
> +            }
>               dprintf(fd, TARGET_ABI_FMT_lx "-" TARGET_ABI_FMT_lx
>                       " %c%c%c%c %08" PRIx64 " %02x:%02x %d %s%s\n",
> -                    h2g(min), h2g(max), flag_r, flag_w,
> +                    h2g(min), h2g(max - 1) + 1, flag_r, flag_w,
>                       flag_x, flag_p, offset, dev_maj, dev_min, inode,
>                       path[0] ? "         " : "", path);
>           }
> @@ -5133,14 +5136,6 @@ static int open_self_maps(void *cpu_env, int fd)
>       free(line);
>       fclose(fp);
>
> -#if defined(TARGET_ARM) || defined(TARGET_M68K) ||
> defined(TARGET_UNICORE32)
> -    dprintf(fd, "%08llx-%08llx rw-p %08llx 00:00 0          [stack]\n",
> -                (unsigned long long)ts->info->stack_limit,
> -                (unsigned long long)(ts->info->start_stack +
> -                                     (TARGET_PAGE_SIZE - 1)) &
> TARGET_PAGE_MASK,
> -                (unsigned long long)0);
> -#endif
> -
>       return 0;
>   }
>