criu/syscall-common-x86-64.S

#include "linkage.h"

#define SYSCALL(name, opcode)		\
	ENTRY(name);			\
	movl	$opcode, %eax;		\
	jmp	__syscall_common;	\
	END(name)

	.text
	.align	4

ENTRY(__syscall_common)
	movq	%rcx, %r10
	syscall
	ret
END(__syscall_common)
syscalls: Complete redesign v9 At early days we've been using only a few syscalls which together with debug compiler options always produce relative addresses for memory variables used in parasite and restorer blobs. Thus it came in unnoticed that there is something worng with syscalls declarations we use. Basically all our syscalls are just a wrappers over inline assembly code in form of static long syscall2(int nr, long arg0, long arg1) { long ret; asm volatile( "movl %1, %%eax \t\n" "movq %2, %%rdi \t\n" "movq %3, %%rsi \t\n" "syscall \t\n" "movq %%rax, %0 \t\n" : "=r"(ret) : "g" ((int)nr), "g" (arg0), "g" (arg1) : "rax", "rdi", "rsi", "memory"); return ret; } so every argument treated to be plain long (even if the call sematics implies it's a memory address passed but not some integer direct value) and transferred via general purpose register. As being mentioned it caused no problems when debug options specified at compile time, the compiler do not tries to optimize addressing but generates code which always compute them. The situation is changed if one is building crtools with optimization enabled -- the compiler finds that arguments are rather plain long numbers and might pass direct addresses of variables, instead of generating relative addresses (because function declarations have no pointers and 'g' in cope with 'mov' is used, which is of course wrong). To fix all this -- now syscalls declarations are generated from syscall.def file and function arguments are passed in conform with x86-64 ABI. This shrinks amount of source code needed to declare syscalls and opens a way to use optimization. Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Pavel Emelyanov <xemul@parallels.com> 2012-04-18 18:10:12 +04:00			`#include "linkage.h"`

			`#define SYSCALL(name, opcode) \`
			`ENTRY(name); \`
			`movl $opcode, %eax; \`
			`jmp __syscall_common; \`
			`END(name)`

			`.text`
			`.align 4`

			`ENTRY(__syscall_common)`
			`movq %rcx, %r10`
			`syscall`
			`ret`
			`END(__syscall_common)`