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Re: [patch] Fix CLONE_VM vs. TLS [Re: Is CLONE_VM really needed in gdbserver?]
On Fri, 29 Jan 2010 03:30:43 +0100, Daniel Jacobowitz wrote:
> On Fri, Jan 29, 2010 at 02:26:25AM +0100, Jan Kratochvil wrote:
> > CodeSourcery arm-2009q3-66-arm-uclinuxeabi-i686-pc-linux-gnu.tar.bz2 gcc sets
> > __uClinux__ although gdb/gdbserver/linux-low.c depends on __UCLIBC__.
> > CLONE_VM is a kernel feature so gcc should be more appropriate but maybe it
> > does not matter.
>
> It's the __UCLIBC_HAS_MMU__ / __ARCH_HAS_MMU__ that make this OK; the end
> result is functionally equivalent to a __uClinux__ check. uClibc can
> be used on full Linux too, and there you have fork.
In such case __uClinux__ can be unified with what is already in use in
linux-low.c.
Going to check it in in some times as this change is IMO pre-approved.
Thanks,
Jan
gdb/gdbserver/
2010-01-29 Jan Kratochvil <jan.kratochvil@redhat.com>
PR libc/11214:
* linux-low.c (linux_tracefork_child) [!(__UCLIBC__ && HAS_NOMMU)]: New.
(linux_test_for_tracefork): Move `stack' into [__UCLIBC__ && HAS_NOMMU].
(linux_test_for_tracefork) [!(__UCLIBC__ && HAS_NOMMU)]: New.
gdb/testsuite/
2010-01-29 Jan Kratochvil <jan.kratochvil@redhat.com>
PR libc/11214:
* gdb.threads/current-lwp-dead.c: Include features.h.
(HAS_NOMMU): New.
(fn, main): Move CLONE_VM into [__UCLIBC__ && HAS_NOMMU].
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -2586,6 +2586,14 @@ linux_tracefork_child (void *arg)
{
ptrace (PTRACE_TRACEME, 0, 0, 0);
kill (getpid (), SIGSTOP);
+
+#if !(defined(__UCLIBC__) && defined(HAS_NOMMU))
+
+ if (fork () == 0)
+ linux_tracefork_grandchild (NULL);
+
+#else /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
+
#ifdef __ia64__
__clone2 (linux_tracefork_grandchild, arg, STACK_SIZE,
CLONE_VM | SIGCHLD, NULL);
@@ -2593,6 +2601,9 @@ linux_tracefork_child (void *arg)
clone (linux_tracefork_grandchild, arg + STACK_SIZE,
CLONE_VM | SIGCHLD, NULL);
#endif
+
+#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
+
_exit (0);
}
@@ -2605,18 +2616,31 @@ linux_test_for_tracefork (void)
{
int child_pid, ret, status;
long second_pid;
+#if defined(__UCLIBC__) && defined(HAS_NOMMU)
char *stack = xmalloc (STACK_SIZE * 4);
+#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
linux_supports_tracefork_flag = 0;
+#if !(defined(__UCLIBC__) && defined(HAS_NOMMU))
+
+ child_pid = fork ();
+ if (child_pid == 0)
+ linux_tracefork_child (NULL);
+
+#else /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
+
/* Use CLONE_VM instead of fork, to support uClinux (no MMU). */
#ifdef __ia64__
child_pid = __clone2 (linux_tracefork_child, stack, STACK_SIZE,
CLONE_VM | SIGCHLD, stack + STACK_SIZE * 2);
-#else
+#else /* !__ia64__ */
child_pid = clone (linux_tracefork_child, stack + STACK_SIZE,
CLONE_VM | SIGCHLD, stack + STACK_SIZE * 2);
-#endif
+#endif /* !__ia64__ */
+
+#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
+
if (child_pid == -1)
perror_with_name ("clone");
@@ -2685,7 +2709,9 @@ linux_test_for_tracefork (void)
}
while (WIFSTOPPED (status));
+#if defined(__UCLIBC__) && defined(HAS_NOMMU)
free (stack);
+#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
}
--- a/gdb/testsuite/gdb.threads/current-lwp-dead.c
+++ b/gdb/testsuite/gdb.threads/current-lwp-dead.c
@@ -30,6 +30,13 @@
#include <unistd.h>
#include <stdlib.h>
+#include <features.h>
+#ifdef __UCLIBC__
+#if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
+#define HAS_NOMMU
+#endif
+#endif
+
#define STACK_SIZE 0x1000
static int
@@ -51,8 +58,11 @@ fn (void *unused)
stack = malloc (STACK_SIZE);
assert (stack != NULL);
- new_pid = clone (fn_return, stack + STACK_SIZE, CLONE_FILES | CLONE_VM, NULL,
- NULL, NULL, NULL);
+ new_pid = clone (fn_return, stack + STACK_SIZE, CLONE_FILES
+#if defined(__UCLIBC__) && defined(HAS_NOMMU)
+ | CLONE_VM
+#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
+ , NULL, NULL, NULL, NULL);
assert (new_pid > 0);
return 0;
@@ -67,8 +77,11 @@ main (int argc, char **argv)
stack = malloc (STACK_SIZE);
assert (stack != NULL);
- new_pid = clone (fn, stack + STACK_SIZE, CLONE_FILES | CLONE_VM, NULL, NULL,
- NULL, NULL);
+ new_pid = clone (fn, stack + STACK_SIZE, CLONE_FILES
+#if defined(__UCLIBC__) && defined(HAS_NOMMU)
+ | CLONE_VM
+#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
+ , NULL, NULL, NULL, NULL);
assert (new_pid > 0);
return 0;