Used by runc.

Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com>
---
 linux-user/syscall.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 2947e79dc0..e739921e86 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -35,6 +35,7 @@
 #include <sys/prctl.h>
 #include <sys/resource.h>
 #include <sys/swap.h>
+#include <sys/syscall.h>
 #include <linux/capability.h>
 #include <sched.h>
 #include <sys/timex.h>
@@ -8254,6 +8255,11 @@ static int host_to_target_cpu_mask(const unsigned long *host_mask,
     return 0;
 }
 
+static int pivot_root(const char *new_root, const char *put_old)
+{
+    return syscall(SYS_pivot_root, new_root, put_old);
+}
+
 /* This is an internal helper for do_syscall so that it is easier
  * to have a single return point, so that actions, such as logging
  * of syscall results, can be performed.
@@ -13222,6 +13228,23 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
         return ret;
 #endif
 
+#if defined(TARGET_NR_pivot_root)
+    case TARGET_NR_pivot_root:
+        {
+            void *p2;
+            p = lock_user_string(arg1); /* new_root */
+            p2 = lock_user_string(arg2); /* put_old */
+            if (!p || !p2) {
+                ret = -TARGET_EFAULT;
+            } else {
+                ret = get_errno(pivot_root(p, p2));
+            }
+            unlock_user(p2, arg2, 0);
+            unlock_user(p, arg1, 0);
+        }
+        return ret;
+#endif
+
     default:
         qemu_log_mask(LOG_UNIMP, "Unsupported syscall: %d\n", num);
         return -TARGET_ENOSYS;
-- 
2.21.1 (Apple Git-122.3)

Le 24/05/2021 à 06:54, YAMAMOTO Takashi a écrit :
> Used by runc.
> 
> Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com>
> ---
>  linux-user/syscall.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 2947e79dc0..e739921e86 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -35,6 +35,7 @@
>  #include <sys/prctl.h>
>  #include <sys/resource.h>
>  #include <sys/swap.h>
> +#include <sys/syscall.h>

we don't need that include, see below

>  #include <linux/capability.h>
>  #include <sched.h>
>  #include <sys/timex.h>
> @@ -8254,6 +8255,11 @@ static int host_to_target_cpu_mask(const unsigned long *host_mask,
>      return 0;
>  }
>  
> +static int pivot_root(const char *new_root, const char *put_old)
> +{
> +    return syscall(SYS_pivot_root, new_root, put_old);
> +}

Better to use:

#if defined(TARGET_NR_pivot_root) && defined(__NR_pivot_root)
_syscall2(int, pivot_root, const char *, new_root, const char *, put_old)
#endif

> +
>  /* This is an internal helper for do_syscall so that it is easier
>   * to have a single return point, so that actions, such as logging
>   * of syscall results, can be performed.
> @@ -13222,6 +13228,23 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
>          return ret;
>  #endif
>  
> +#if defined(TARGET_NR_pivot_root)
> +    case TARGET_NR_pivot_root:
> +        {
> +            void *p2;
> +            p = lock_user_string(arg1); /* new_root */
> +            p2 = lock_user_string(arg2); /* put_old */
> +            if (!p || !p2) {
> +                ret = -TARGET_EFAULT;
> +            } else {
> +                ret = get_errno(pivot_root(p, p2));
> +            }
> +            unlock_user(p2, arg2, 0);
> +            unlock_user(p, arg1, 0);
> +        }
> +        return ret;
> +#endif
> +
>      default:
>          qemu_log_mask(LOG_UNIMP, "Unsupported syscall: %d\n", num);
>          return -TARGET_ENOSYS;
> 

Thanks,
Laurent

On Wed, May 26, 2021 at 5:22 AM Laurent Vivier <laurent@vivier.eu> wrote:
>
> Le 24/05/2021 à 06:54, YAMAMOTO Takashi a écrit :
> > Used by runc.
> >
> > Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com>
> > ---
> >  linux-user/syscall.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> > index 2947e79dc0..e739921e86 100644
> > --- a/linux-user/syscall.c
> > +++ b/linux-user/syscall.c
> > @@ -35,6 +35,7 @@
> >  #include <sys/prctl.h>
> >  #include <sys/resource.h>
> >  #include <sys/swap.h>
> > +#include <sys/syscall.h>
>
> we don't need that include, see below
>
> >  #include <linux/capability.h>
> >  #include <sched.h>
> >  #include <sys/timex.h>
> > @@ -8254,6 +8255,11 @@ static int host_to_target_cpu_mask(const unsigned long *host_mask,
> >      return 0;
> >  }
> >
> > +static int pivot_root(const char *new_root, const char *put_old)
> > +{
> > +    return syscall(SYS_pivot_root, new_root, put_old);
> > +}
>
> Better to use:
>
> #if defined(TARGET_NR_pivot_root) && defined(__NR_pivot_root)
> _syscall2(int, pivot_root, const char *, new_root, const char *, put_old)
> #endif

ok. i haven't noticed the _syscall2 macro in this file. thank you.

>
> > +
> >  /* This is an internal helper for do_syscall so that it is easier
> >   * to have a single return point, so that actions, such as logging
> >   * of syscall results, can be performed.
> > @@ -13222,6 +13228,23 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
> >          return ret;
> >  #endif
> >
> > +#if defined(TARGET_NR_pivot_root)
> > +    case TARGET_NR_pivot_root:
> > +        {
> > +            void *p2;
> > +            p = lock_user_string(arg1); /* new_root */
> > +            p2 = lock_user_string(arg2); /* put_old */
> > +            if (!p || !p2) {
> > +                ret = -TARGET_EFAULT;
> > +            } else {
> > +                ret = get_errno(pivot_root(p, p2));
> > +            }
> > +            unlock_user(p2, arg2, 0);
> > +            unlock_user(p, arg1, 0);
> > +        }
> > +        return ret;
> > +#endif
> > +
> >      default:
> >          qemu_log_mask(LOG_UNIMP, "Unsupported syscall: %d\n", num);
> >          return -TARGET_ENOSYS;
> >
>
> Thanks,
> Laurent
>