Patchwork [3/5] linux-user: fake /proc/self/maps

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Submitter Alexander Graf
Date Nov. 2, 2011, 7:23 p.m.
Message ID <1320261806-13194-4-git-send-email-agraf@suse.de>
Download mbox | patch
Permalink /patch/123318/
State New
Headers show

Comments

Alexander Graf - Nov. 2, 2011, 7:23 p.m.
glibc's pthread_attr_getstack tries to find the stack range from
/proc/self/maps. Unfortunately, /proc is usually the host's /proc
which means linux-user guests see qemu's stack there.

Fake the file with a constructed maps entry that exposes the guest's
stack range.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 linux-user/syscall.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)
Alexander Graf - Nov. 3, 2011, 7:28 p.m.
Alexander Graf wrote:
> glibc's pthread_attr_getstack tries to find the stack range from
> /proc/self/maps. Unfortunately, /proc is usually the host's /proc
> which means linux-user guests see qemu's stack there.
>
> Fake the file with a constructed maps entry that exposes the guest's
> stack range.
>
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  linux-user/syscall.c |   15 +++++++++++++++
>  1 files changed, 15 insertions(+), 0 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 38953ba..a51b457 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -4600,6 +4600,20 @@ int get_osversion(void)
>      return osversion;
>  }
>  
> +
> +static int open_self_maps(void *cpu_env, int fd)
> +{
> +    TaskState *ts = ((CPUState *)cpu_env)->opaque;
> +
> +    dprintf(fd, "%08llx-%08llx rw-p %08llx 00:00 0          [stack]\n",
> +                (unsigned long long)ts->info->stack_limit,
> +                (unsigned long long)(ts->stack_base + (TARGET_PAGE_SIZE - 1))
> +                                     & TARGET_PAGE_MASK,
>   

This needs to be guarded by:

#if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_UNICORE32)

Any idea how to fetch the stack range from somewhere else for other archs?

Alex

Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 38953ba..a51b457 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4600,6 +4600,20 @@  int get_osversion(void)
     return osversion;
 }
 
+
+static int open_self_maps(void *cpu_env, int fd)
+{
+    TaskState *ts = ((CPUState *)cpu_env)->opaque;
+
+    dprintf(fd, "%08llx-%08llx rw-p %08llx 00:00 0          [stack]\n",
+                (unsigned long long)ts->info->stack_limit,
+                (unsigned long long)(ts->stack_base + (TARGET_PAGE_SIZE - 1))
+                                     & TARGET_PAGE_MASK,
+                (unsigned long long)ts->stack_base);
+
+    return 0;
+}
+
 static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode)
 {
     struct fake_open {
@@ -4608,6 +4622,7 @@  static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode)
     };
     const struct fake_open *fake_open;
     static const struct fake_open fakes[] = {
+        { "/proc/self/maps", open_self_maps },
         { NULL, NULL }
     };