Re: [Valgrind-users] Re: [uml-devel] Re: UML and valgrind

["D. Bahi" <dbahi@enterasys.com>]

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trying to find a way to wedge the old patch into
the new code... i don't think it applies anymore.

alright, i don't read assembly (head hung low) but
valgrind 2.1.2/coregrind/vg_syscall.S has something
that makes me ask why i'm getting the 'clone() not
supported message'

does this need some kind of tie-in code in vg_syscalls.c?

.globl VG_(clone)
VG_(clone):
#define FSZ	(4+4+4)			/* frame size = retaddr+ebx+edi */
	push	%ebx
	push	%edi
	/* set up child stack with function and arg */
	movl	 4+FSZ(%esp), %ecx	/* child stack */
	movl	12+FSZ(%esp), %ebx	/* fn arg */
	movl	 0+FSZ(%esp), %eax	/* fn */
	lea	-8(%ecx), %ecx		/* make space on stack */
	movl	%ebx, 4(%ecx)		/*   fn arg */
	movl	%eax, 0(%ecx)		/*   fn */

	/* get other args to clone */
	movl	 8+FSZ(%esp), %ebx	/* flags */
	movl	20+FSZ(%esp), %edx	/* parent tid * */
	movl	16+FSZ(%esp), %edi	/* child tid * */
	movl	$__NR_clone, %eax
	int	$0x80
	testl	%eax, %eax
	jnz	1f

	/* CHILD - call thread function */
	popl	%eax
	call	*%eax

	/* exit with result */
	movl	%eax, %ebx
	movl	$__NR_exit, %eax
	int	$0x80

	/* Hm, exit returned */
	ud2
		
1:	/* PARENT or ERROR */
	pop	%edi
	pop	%ebx
	ret


Jeff Dike wrote:

> dbahi@enterasys.com said:
> 
>>ugh, so close - it bails - stopped by clone() !?!!?? : 
> 
> 
> OK, there were a bunch of problems that were fixed when me, Jeremy, and Julian
> were working on this.  The clone one seems to have not made it.  I've lost the
> patches I had, but I dug this out of a piece of email.  It applies to 
> coregrind/vg_syscalls.c:
> 
> 
>>@@ -39,6 +40,10 @@
>> # code which copies from baseBlock before the call, into
>> # m_state_static, and back afterwards.
>> 
>>+.section .data
>>+save_ip:
>>+        .long   0
>>+
>> VG_(do_syscall):
>>        # Save all the int registers of the real machines state on the
>>        # simulators stack.
>>@@ -80,10 +85,27 @@
>>        movl    VG_(m_state_static)+48, %esi
>>        movl    VG_(m_state_static)+52, %edi
>> 
>>+       cmpl    $__NR_clone, %eax
>>+       jne     not_clone
>>+
>>+       pushl   %eax
>>+       movl    VG_(m_state_static)+60, %eax
>>+       movl    %eax, save_ip
>>+       popl    %eax
>>+
>>+       int     $0x80
>>+
>>+       cmpl    $0, %eax
>>+       jne     parent_finish
>>+
>>+       jmp     *save_ip
>>+
>>+not_clone:
>>        # esp now refers to the simulatees stack
>>        # Do the actual system call
>>        int     $0x80
> 
> 
> It handles the clone by calling clone itself, creating a new valgrind thread
> which will go on grinding the new UML thread.
> 
> Also, I saw this:
> 
> 
>>	valgrind: the `impossible' happened:
>>	   Unhandled REPE case
> 
> 
> If you see this, check that you have
> 	http://www.goop.org/~jeremy/valgrind/76-repe-scas.patch
> and apply if not.
> 
> 				Jeff
> 

-- 
There are two kinds of people in this world: Those that enter a room and 
turn the television set on, and those that enter a room and turn the 
television set off. -- Raymond Shaw, The Manchurian Candidate (1962).

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