diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/ia64/clone2.S')
| -rw-r--r-- | sysdeps/unix/sysv/linux/ia64/clone2.S | 57 |
1 files changed, 32 insertions, 25 deletions
diff --git a/sysdeps/unix/sysv/linux/ia64/clone2.S b/sysdeps/unix/sysv/linux/ia64/clone2.S index 17620ff646..968d1e811c 100644 --- a/sysdeps/unix/sysv/linux/ia64/clone2.S +++ b/sysdeps/unix/sysv/linux/ia64/clone2.S @@ -25,49 +25,56 @@ /* size_t child_stack_size, int flags, void *arg, */ /* pid_t *parent_tid, void *tls, pid_t *child_tid) */ +#define CHILD p8 +#define PARENT p9 + ENTRY(__clone2) - alloc r2=ar.pfs,8,2,6,0 + .prologue + alloc r2=ar.pfs,8,0,6,0 cmp.eq p6,p0=0,in0 mov r8=EINVAL -(p6) br.cond.spnt.few __syscall_error - ;; - flushrs /* This is necessary, since the child */ - /* will be running with the same */ - /* register backing store for a few */ - /* instructions. We need to ensure */ - /* that it will not read or write the */ - /* backing store. */ - mov loc0=in0 /* save fn */ - mov loc1=in4 /* save arg */ mov out0=in3 /* Flags are first syscall argument. */ mov out1=in1 /* Stack address. */ +(p6) br.cond.spnt.many __syscall_error + ;; mov out2=in2 /* Stack size. */ mov out3=in5 /* Parent TID Pointer */ mov out4=in7 /* Child TID Pointer */ mov out5=in6 /* TLS pointer */ - DO_CALL (SYS_ify (clone2)) + /* + * clone2() is special: the child cannot execute br.ret right + * after the system call returns, because it starts out + * executing on an empty stack. Because of this, we can't use + * the new (lightweight) syscall convention here. Instead, we + * just fall back on always using "break". + * + * Furthermore, since the child starts with an empty stack, we + * need to avoid unwinding past invalid memory. To that end, + * we'll pretend now that __clone2() is the end of the + * call-chain. This is wrong for the parent, but only until + * it returns from clone2() but it's better than the + * alternative. + */ + mov r15=SYS_ify (clone2) + .save rp, r0 + break __BREAK_SYSCALL + .body cmp.eq p6,p0=-1,r10 + cmp.eq CHILD,PARENT=0,r8 /* Are we the child? */ +(p6) br.cond.spnt.many __syscall_error ;; -(p6) br.cond.spnt.few __syscall_error - -# define CHILD p6 -# define PARENT p7 - cmp.eq CHILD,PARENT=0,r8 /* Are we the child? */ - ;; -(CHILD) ld8 out1=[loc0],8 /* Retrieve code pointer. */ -(CHILD) mov out0=loc1 /* Pass proper argument to fn */ +(CHILD) ld8 out1=[in0],8 /* Retrieve code pointer. */ +(CHILD) mov out0=in4 /* Pass proper argument to fn */ (PARENT) ret ;; - ld8 gp=[loc0] /* Load function gp. */ + ld8 gp=[in0] /* Load function gp. */ mov b6=out1 - ;; - br.call.dptk.few rp=b6 /* Call fn(arg) in the child */ + br.call.dptk.many rp=b6 /* Call fn(arg) in the child */ ;; mov out0=r8 /* Argument to _exit */ .globl _exit - br.call.dpnt.few rp=_exit /* call _exit with result from fn. */ + br.call.dpnt.many rp=_exit /* call _exit with result from fn. */ ret /* Not reached. */ - PSEUDO_END(__clone2) /* For now we leave __clone undefined. This is unlikely to be a */ |