[PATCH v6 1/7] um: Add generic stub_syscall6 function

[Benjamin Berg]

This function will be used by the new static stub binary.

Signed-off-by: Benjamin Berg <benja...@sipsolutions.net>
---
 arch/x86/um/shared/sysdep/stub_32.h | 22 ++++++++++++++++++++++
 arch/x86/um/shared/sysdep/stub_64.h | 16 ++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/arch/x86/um/shared/sysdep/stub_32.h 
b/arch/x86/um/shared/sysdep/stub_32.h
index ea8b5a2d67af..ca2dd9263cf2 100644
--- a/arch/x86/um/shared/sysdep/stub_32.h
+++ b/arch/x86/um/shared/sysdep/stub_32.h
@@ -79,6 +79,28 @@ static __always_inline long stub_syscall5(long syscall, long 
arg1, long arg2,
        return ret;
 }
 
+static __always_inline long stub_syscall6(long syscall, long arg1, long arg2,
+                                         long arg3, long arg4, long arg5,
+                                         long arg6)
+{
+       struct syscall_args {
+               int ebx, ebp;
+       } args = { arg1, arg6 };
+       long ret;
+
+       __asm__ volatile ("pushl %%ebp;"
+                       "movl 0x4(%%ebx),%%ebp;"
+                       "movl (%%ebx),%%ebx;"
+                       "int $0x80;"
+                       "popl %%ebp"
+                       : "=a" (ret)
+                       : "0" (syscall), "b" (&args),
+                       "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
+                       : "memory");
+
+       return ret;
+}
+
 static __always_inline void trap_myself(void)
 {
        __asm("int3");
diff --git a/arch/x86/um/shared/sysdep/stub_64.h 
b/arch/x86/um/shared/sysdep/stub_64.h
index b24168ef0ac4..c99ea6e06f96 100644
--- a/arch/x86/um/shared/sysdep/stub_64.h
+++ b/arch/x86/um/shared/sysdep/stub_64.h
@@ -79,6 +79,22 @@ static __always_inline long stub_syscall5(long syscall, long 
arg1, long arg2,
        return ret;
 }
 
+static __always_inline long stub_syscall6(long syscall, long arg1, long arg2,
+                                         long arg3, long arg4, long arg5,
+                                         long arg6)
+{
+       long ret;
+
+       __asm__ volatile ("movq %5,%%r10 ; movq %6,%%r8 ; movq %7,%%r9 ; "
+               __syscall
+               : "=a" (ret)
+               : "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
+                 "g" (arg4), "g" (arg5), "g" (arg6)
+               : __syscall_clobber, "r10", "r8", "r9");
+
+       return ret;
+}
+
 static __always_inline void trap_myself(void)
 {
        __asm("int3");
-- 
2.45.2