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, 0 insertions, 7 deletions

diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h
index 2fd5926..5d98d0b6 100644
--- a/arch/x86/include/asm/linkage.h
+++ b/arch/x86/include/asm/linkage.h
@@ -18,13 +18,6 @@
 #define asmregparm __attribute__((regparm(3)))
 
 /*
- * For syscalls that need a pointer to the pt_regs struct (ie. fork).
- * The regs pointer is passed in %eax as the first argument.  The
- * remaining function arguments remain on the stack.
- */
-#define ptregscall __attribute__((regparm(1)))
-
-/*
  * Make sure the compiler doesn't do anything stupid with the
  * arguments on the stack - they are owned by the *caller*, not
  * the callee. This just fools gcc into not spilling into them,