x86: use regparm(3) for passed-in pt_regs pointer

Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it.  This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to take the pointer as an argument instead of relying on
the assumption that the pt_regs structure overlaps the function
arguments.

Drop the use of regparm(1) due to concern about gcc bugs, and to move
in the direction of the eventual removal of regparm(0) for asmlinkage.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 10 insertions, 15 deletions

diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index 617295255a17..77bb31a88ba8 100644
--- a/arch/x86/include/asm/syscalls.h
+++ b/arch/x86/include/asm/syscalls.h
@@ -29,26 +29,21 @@ asmlinkage int sys_get_thread_area(struct user_desc __user *);
 /* X86_32 only */
 #ifdef CONFIG_X86_32
 /* kernel/process_32.c */
-ptregscall int sys_fork(struct pt_regs *);
-ptregscall int sys_clone(struct pt_regs *, unsigned long,
-                         unsigned long, int __user *,
-                         unsigned long, int __user *);
-ptregscall int sys_vfork(struct pt_regs *);
-ptregscall int sys_execve(struct pt_regs *, char __user *,
-                          char __user * __user *,
-                          char __user * __user *);
+int sys_fork(struct pt_regs *);
+int sys_clone(struct pt_regs *);
+int sys_vfork(struct pt_regs *);
+int sys_execve(struct pt_regs *);
 
 /* kernel/signal_32.c */
 asmlinkage int sys_sigsuspend(int, int, old_sigset_t);
 asmlinkage int sys_sigaction(int, const struct old_sigaction __user *,
                              struct old_sigaction __user *);
-ptregscall int sys_sigaltstack(struct pt_regs *, const stack_t __user *,
-                               stack_t __user *);
-ptregscall unsigned long sys_sigreturn(struct pt_regs *);
-ptregscall int sys_rt_sigreturn(struct pt_regs *);
+int sys_sigaltstack(struct pt_regs *);
+unsigned long sys_sigreturn(struct pt_regs *);
+int sys_rt_sigreturn(struct pt_regs *);
 
 /* kernel/ioport.c */
-ptregscall long sys_iopl(struct pt_regs *, unsigned int);
+long sys_iopl(struct pt_regs *);
 
 /* kernel/sys_i386_32.c */
 asmlinkage long sys_mmap2(unsigned long, unsigned long, unsigned long,
@@ -64,8 +59,8 @@ struct oldold_utsname;
 asmlinkage int sys_olduname(struct oldold_utsname __user *);
 
 /* kernel/vm86_32.c */
-ptregscall int sys_vm86old(struct pt_regs *, struct vm86_struct __user *);
-ptregscall int sys_vm86(struct pt_regs *, unsigned long, unsigned long);
+int sys_vm86old(struct pt_regs *);
+int sys_vm86(struct pt_regs *);
 
 #else /* CONFIG_X86_32 */