linux-user: Clean up handling of clone() argument order

Linux manages to have three separate orderings of the arguments to
the clone() syscall on different architectures. In the kernel these
are selected via CONFIG_CLONE_BACKWARDS and CONFIG_CLONE_BACKWARDS2.
Clean up our implementation of this to use similar #define names
rather than a TARGET_* ifdef ladder.

This includes behaviour changes fixing bugs on cris, x86-64, m68k,
openrisc and unicore32.  cris had explicit but wrong handling; the
others were just incorrectly using QEMU's default, which happened
to be the equivalent of CONFIG_CLONE_BACKWARDS. (unicore32 appears
to be broken in the mainline kernel in that it tries to use arg3 for
both parent_tidptr and newtls simultaneously -- we don't attempt
to emulate this bug...)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

11 files changed, 41 insertions, 7 deletions

diff --git a/linux-user/arm/syscall.h b/linux-user/arm/syscall.h
index 003d424..73f2931 100644
--- a/linux-user/arm/syscall.h
+++ b/linux-user/arm/syscall.h
@@ -40,3 +40,5 @@ struct target_pt_regs {
 #else
 #define UNAME_MACHINE "armv5tel"
 #endif
+
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/cris/syscall.h b/linux-user/cris/syscall.h
index 50e50b4..832ee64 100644
--- a/linux-user/cris/syscall.h
+++ b/linux-user/cris/syscall.h
@@ -38,4 +38,6 @@ struct target_pt_regs {
         unsigned long eda;
 };
 
+#define TARGET_CLONE_BACKWARDS2
+
 #endif
diff --git a/linux-user/i386/syscall.h b/linux-user/i386/syscall.h
index 266e2c4..12b8c3b 100644
--- a/linux-user/i386/syscall.h
+++ b/linux-user/i386/syscall.h
@@ -144,3 +144,5 @@ struct target_vm86plus_struct {
 };
 
 #define UNAME_MACHINE "i686"
+
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/microblaze/syscall.h b/linux-user/microblaze/syscall.h
index c3e5c55..d550989 100644
--- a/linux-user/microblaze/syscall.h
+++ b/linux-user/microblaze/syscall.h
@@ -48,4 +48,6 @@ struct target_pt_regs {
         uint32_t kernel_mode;
 };
 
+#define TARGET_CLONE_BACKWARDS
+
 #endif
diff --git a/linux-user/mips/syscall.h b/linux-user/mips/syscall.h
index 3deb862..9d437d9 100644
--- a/linux-user/mips/syscall.h
+++ b/linux-user/mips/syscall.h
@@ -225,3 +225,5 @@ struct target_pt_regs {
 #define TARGET_QEMU_ESIGRETURN 255
 
 #define UNAME_MACHINE "mips"
+
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/mips64/syscall.h b/linux-user/mips64/syscall.h
index cd707df..1710f76 100644
--- a/linux-user/mips64/syscall.h
+++ b/linux-user/mips64/syscall.h
@@ -222,3 +222,5 @@ struct target_pt_regs {
 #define TARGET_QEMU_ESIGRETURN 255
 
 #define UNAME_MACHINE "mips64"
+
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/ppc/syscall.h b/linux-user/ppc/syscall.h
index 481047b..ba36acb 100644
--- a/linux-user/ppc/syscall.h
+++ b/linux-user/ppc/syscall.h
@@ -62,3 +62,5 @@ struct target_revectored_struct {
 #else
 #define UNAME_MACHINE "ppc"
 #endif
+
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/s390x/syscall.h b/linux-user/s390x/syscall.h
index e4603b7..ea8c304 100644
--- a/linux-user/s390x/syscall.h
+++ b/linux-user/s390x/syscall.h
@@ -21,3 +21,5 @@ struct target_pt_regs {
 };
 
 #define UNAME_MACHINE "s390x"
+
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/sparc/syscall.h b/linux-user/sparc/syscall.h
index 5a9bb7e..4cd64bf 100644
--- a/linux-user/sparc/syscall.h
+++ b/linux-user/sparc/syscall.h
@@ -7,3 +7,10 @@ struct target_pt_regs {
 };
 
 #define UNAME_MACHINE "sun4"
+
+/* SPARC kernels don't define this in their Kconfig, but they have the
+ * same ABI as if they did, implemented by sparc-specific code which fishes
+ * directly in the u_regs() struct for half the parameters in sparc_do_fork()
+ * and copy_thread().
+ */
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/sparc64/syscall.h b/linux-user/sparc64/syscall.h
index 81a816d..e60bf31 100644
--- a/linux-user/sparc64/syscall.h
+++ b/linux-user/sparc64/syscall.h
@@ -8,3 +8,10 @@ struct target_pt_regs {
 };
 
 #define UNAME_MACHINE "sun4u"
+
+/* SPARC kernels don't define this in their Kconfig, but they have the
+ * same ABI as if they did, implemented by sparc-specific code which fishes
+ * directly in the u_regs() struct for half the parameters in sparc_do_fork()
+ * and copy_thread().
+ */
+#define TARGET_CLONE_BACKWARDS
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 642d0a3..b167d7f 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6956,16 +6956,20 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         ret = get_errno(fsync(arg1));
         break;
     case TARGET_NR_clone:
-#if defined(TARGET_SH4) || defined(TARGET_ALPHA)
-        ret = get_errno(do_fork(cpu_env, arg1, arg2, arg3, arg5, arg4));
-#elif defined(TARGET_CRIS)
-        ret = get_errno(do_fork(cpu_env, arg2, arg1, arg3, arg4, arg5));
-#elif defined(TARGET_MICROBLAZE)
+        /* Linux manages to have three different orderings for its
+         * arguments to clone(); the BACKWARDS and BACKWARDS2 defines
+         * match the kernel's CONFIG_CLONE_* settings.
+         * Microblaze is further special in that it uses a sixth
+         * implicit argument to clone for the TLS pointer.
+         */
+#if defined(TARGET_MICROBLAZE)
         ret = get_errno(do_fork(cpu_env, arg1, arg2, arg4, arg6, arg5));
-#elif defined(TARGET_S390X)
+#elif defined(TARGET_CLONE_BACKWARDS)
+        ret = get_errno(do_fork(cpu_env, arg1, arg2, arg3, arg4, arg5));
+#elif defined(TARGET_CLONE_BACKWARDS2)
         ret = get_errno(do_fork(cpu_env, arg2, arg1, arg3, arg5, arg4));
 #else
-        ret = get_errno(do_fork(cpu_env, arg1, arg2, arg3, arg4, arg5));
+        ret = get_errno(do_fork(cpu_env, arg1, arg2, arg3, arg5, arg4));
 #endif
         break;
 #ifdef __NR_exit_group