From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: updated x86_64 eclone() stub Date: Fri, 04 Dec 2009 07:29:27 -0800 Message-ID: <1259940567.32391.4950.camel@nimitz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: containers List-Id: containers.vger.kernel.org This more closely resembles what glibc does. The last version had a push/popq %ebp. But, after looking at the glibc code, I believe this to be unnecessary on 64-bit. Suka also pointed out that we were neglecting to pull the subthread's function argument off the stack. I also changed the register being used for the subthread variable to be rax. This is just to more closely resemble the glibc code. It doesn't hurt to use it this way mostly because we overwrite it for the exit syscall anyway. int eclone(long flags_low, struct clone_args *clone_args, long args_size, int *pids) { long retval; __asm__ __volatile__( "movq %5, %%r10\n\t" /* pids in r10*/ "syscall\n\t" /* Linux/x86_64 system call */ "testq %0,%0\n\t" /* check return value */ "jne 1f\n\t" /* jump if parent */ "popq %%rax\n\t" /* get subthread function */ "popq %%rdi\n\t" /* get the subthread function arg */ "call *%%rax\n\t" /* start subthread function */ "movq %6,%0\n\t" "syscall\n" /* exit system call: exit subthread */ "1:\n\t" :"=a" (retval) :"0" (__NR_clone3),/* eax */ "D" (flags_low), /* rdi */ "S" (clone_args), /* rsi */ "d" (args_size), /* rdx */ "m" (pids), /* gets moved to r10 */ "i" (__NR_exit) :"rbx", "rcx", "r8", "r9", "r10" ); if (retval < 0) { errno = -retval; retval = -1; } return retval; } -- Dave