[RESEND PATCH v2] microblaze: Fix clone syscall

[Michal Simek]

Microblaze was assign to CLONE_BACKWARDS type where
parent tid was passed via 3rd argument.
Microblaze glibc is using 4th argument for it.

Create new CLONE_BACKWARDS3 type where stack_size is passed
via 3rd argument, parent thread id pointer via 4th,
child thread id pointer via 5th and tls value as 6th
argument

Inconsistency was introduced by this patch:
"microblaze: switch to generic fork/vfork/clone"
(sha1: f3268edbe6fe0ce56e62c6d6b14640aeb04864b7)

Signed-off-by: Michal Simek <michal.si...@xilinx.com>
---
Changes in v2:
 - Add information about the first broken patch - Suggested by Andrew

Hi Al,

We have found this problem based on debugging timer_create()
reported by customer which wasn't cover by LTP testing.
What tool do you use for syscall testing?

IRC there was any discussion about adding syscall tests
directly to the kernel.

I am not sure if there is more elegant way how to fix this
in syscalls.h.

Thanks,
Michal

---
 arch/Kconfig             | 6 ++++++
 arch/microblaze/Kconfig  | 2 +-
 include/linux/syscalls.h | 5 +++++
 kernel/fork.c            | 6 ++++++
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 8d2ae24..1feb169 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -407,6 +407,12 @@ config CLONE_BACKWARDS2
        help
          Architecture has the first two arguments of clone(2) swapped.

+config CLONE_BACKWARDS3
+       bool
+       help
+         Architecture has tls passed as the 3rd argument of clone(2),
+         not the 5th one.
+
 config ODD_RT_SIGACTION
        bool
        help
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index d22a4ec..4fab522 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -28,7 +28,7 @@ config MICROBLAZE
        select GENERIC_CLOCKEVENTS
        select GENERIC_IDLE_POLL_SETUP
        select MODULES_USE_ELF_RELA
-       select CLONE_BACKWARDS
+       select CLONE_BACKWARDS3

 config SWAP
        def_bool n
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 4147d70..71d8931 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -802,9 +802,14 @@ asmlinkage long sys_vfork(void);
 asmlinkage long sys_clone(unsigned long, unsigned long, int __user *, int,
               int __user *);
 #else
+#if CONFIG_CLONE_BACKWARDS3
+asmlinkage long sys_clone(unsigned long, unsigned long, int, int __user *,
+                         int __user *, int);
+#else
 asmlinkage long sys_clone(unsigned long, unsigned long, int __user *,
               int __user *, int);
 #endif
+#endif

 asmlinkage long sys_execve(const char __user *filename,
                const char __user *const __user *argv,
diff --git a/kernel/fork.c b/kernel/fork.c
index 403d2bb..e23bb19 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1679,6 +1679,12 @@ SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned 
long, clone_flags,
                 int __user *, parent_tidptr,
                 int __user *, child_tidptr,
                 int, tls_val)
+#elif defined(CONFIG_CLONE_BACKWARDS3)
+SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
+               int, stack_size,
+               int __user *, parent_tidptr,
+               int __user *, child_tidptr,
+               int, tls_val)
 #else
 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
                 int __user *, parent_tidptr,
--
1.8.2.3

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