Hi,
This patch to do_fork_clone() supports specifying the child stack pointer.
An app may do this when it believes that address space is constrained.
Most callers specify a child stack pointer of 0; the Linux kernel then
uses the actual stack pointer of the caller, thus equivalent to fork().
Patch is against a recent SVN version.
--- ./coregrind/m_syswrap/syswrap-ppc64-linux.c.orig 2007-11-01
12:16:36.000000000 -0700
+++ ./coregrind/m_syswrap/syswrap-ppc64-linux.c 2007-11-05 07:45:32.000000000
-0800
@@ -973,6 +973,7 @@
SET_STATUS_from_SysRes(
ML_(do_fork_clone)(tid,
cloneflags, /* flags */
+ (Addr)ARG2, /* child SP */
(Int *)ARG3, /* parent_tidptr */
(Int *)ARG5)); /* child_tidptr */
break;
--- ./coregrind/m_syswrap/syswrap-amd64-linux.c.orig 2007-11-01
12:16:36.000000000 -0700
+++ ./coregrind/m_syswrap/syswrap-amd64-linux.c 2007-11-05 07:45:32.000000000
-0800
@@ -422,6 +422,7 @@
SET_STATUS_from_SysRes(
ML_(do_fork_clone)(tid,
cloneflags, /* flags */
+ (Addr)ARG2, /* child ESP */
(Int *)ARG3, /* parent_tidptr */
(Int *)ARG4)); /* child_tidptr */
break;
--- ./coregrind/m_syswrap/syswrap-linux.c.orig 2007-11-01 12:16:36.000000000
-0700
+++ ./coregrind/m_syswrap/syswrap-linux.c 2007-11-05 07:46:41.000000000
-0800
@@ -294,7 +294,7 @@
/* Do a clone which is really a fork() */
-SysRes ML_(do_fork_clone) ( ThreadId tid, UInt flags,
+SysRes ML_(do_fork_clone) ( ThreadId tid, UInt flags, Addr child_esp,
Int* parent_tidptr, Int* child_tidptr )
{
vki_sigset_t fork_saved_mask;
@@ -328,6 +328,11 @@
if (!res.isError && res.res == 0) {
/* child */
+ if (child_esp != 0) {
+ ThreadState *const ctst = VG_(get_ThreadState)(tid);
+ ctst->arch.vex.guest_ESP = child_esp;
+ }
+
VG_(do_atfork_child)(tid);
/* restore signal mask */
--- ./coregrind/m_syswrap/syswrap-x86-linux.c.orig 2007-11-01
12:16:36.000000000 -0700
+++ ./coregrind/m_syswrap/syswrap-x86-linux.c 2007-11-05 07:45:32.000000000
-0800
@@ -903,6 +903,7 @@
SET_STATUS_from_SysRes(
ML_(do_fork_clone)(tid,
cloneflags, /* flags */
+ (Addr)ARG2, /* child ESP */
(Int *)ARG3, /* parent_tidptr */
(Int *)ARG5)); /* child_tidptr */
break;
--- ./coregrind/m_syswrap/syswrap-ppc32-linux.c.orig 2007-11-01
12:16:36.000000000 -0700
+++ ./coregrind/m_syswrap/syswrap-ppc32-linux.c 2007-11-05 07:45:32.000000000
-0800
@@ -995,6 +995,7 @@
SET_STATUS_from_SysRes(
ML_(do_fork_clone)(tid,
cloneflags, /* flags */
+ (Addr)ARG2, /* child SP */
(Int *)ARG3, /* parent_tidptr */
(Int *)ARG5)); /* child_tidptr */
break;
--- ./coregrind/m_syswrap/priv_syswrap-linux.h.orig 2007-11-01
12:16:36.000000000 -0700
+++ ./coregrind/m_syswrap/priv_syswrap-linux.h 2007-11-05 07:45:32.000000000
-0800
@@ -38,7 +38,7 @@
extern Addr ML_(allocstack) ( ThreadId tid );
extern void ML_(call_on_new_stack_0_1) ( Addr stack, Addr retaddr,
void (*f)(Word), Word arg1 );
-extern SysRes ML_(do_fork_clone) ( ThreadId tid, UInt flags,
+extern SysRes ML_(do_fork_clone) ( ThreadId tid, UInt flags, Addr child_esp,
Int* parent_tidptr, Int* child_tidptr );
--
John Reiser, [EMAIL PROTECTED]
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