From: Alexey Dobriyan <adobriyan@openvz.org>
To: akpm@osdl.org, roland@redhat.com
Cc: linux-kernel@vger.kernel.org, devel@openvz.org
Subject: utrace regressions (was: -mm merge plans for 2.6.21)
Date: Mon, 12 Feb 2007 15:51:56 +0300 [thread overview]
Message-ID: <20070212125156.GA6035@localhost.sw.ru> (raw)
> utrace-utrace-tracehook.patch
> utrace-utrace-tracehook-ia64.patch
> utrace-utrace-tracehook-sparc64.patch
> utrace-utrace-tracehook-s390.patch
> utrace-utrace-regset.patch
> utrace-utrace-regset-ia64.patch
> utrace-utrace-regset-sparc64.patch
> utrace-utrace-regset-s390.patch
> utrace-utrace-core.patch
> utrace-utrace-ptrace-compat.patch
> utrace-utrace-ptrace-compat-ia64.patch
> utrace-utrace-ptrace-compat-sparc64.patch
> utrace-utrace-ptrace-compat-s390.patch
> utrace just got added to -mm.
We're aware of two regressions compared to mainline if ptrace is utrace:
1) zero holes for PTRACE_PEEKUSR vanished.
strace(1) when sees unknown syscall, does something like:
for (i = 0; i < MAX_ARGS; i++)
if (ptrace(PTRACE_PEEKUSR, i * 4, ...) < 0)
return -1;
since THREAD_SIZE is 17 on x86 which is less that MAX_ARGS (32 on
x86), you'll get -EIO(utrace) or 0(ptrace) when i=0.
No new syscalls stracing for developers.
Proposed patch:
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -728,6 +728,7 @@ EXPORT_SYMBOL_GPL(utrace_i386_native);
#ifdef CONFIG_PTRACE
static const struct ptrace_layout_segment i386_uarea[] = {
{0, FRAME_SIZE*4, 0, 0},
+ {FRAME_SIZE*4, offsetof(struct user, u_debugreg[0]), -1, 0},
{offsetof(struct user, u_debugreg[0]),
offsetof(struct user, u_debugreg[8]), 4, 0},
{0, 0, -1, 0}
Looks like x86_64 also needs zero holes added, haven't checked in runtime.
-------------------------------------------------------------------
2. The following proggie renders box unusable in ~10 seconds (but not
mainline kernel where Ctrl+C will kill process).
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/ptrace.h>
#include <signal.h>
static void *thread_func(void *arg)
{
execl("/proc/self/exe", NULL);
return NULL;
}
int main(int argc, const char *argv[])
{
pthread_t thread;
int pid, n;
if (argv[0] && (pid = fork()))
for (n = 1; /*n < 1000000*/; ++n) {
ptrace(PTRACE_ATTACH, pid, NULL, 0);
ptrace(PTRACE_DETACH, pid, NULL, 0);
if (!(n % 100000))
printf("passed: %d\n", n);
}
if (pthread_create(&thread, NULL, thread_func, NULL))
perror("pthread_create");
while (1)
pause();
return 1;
}
next reply other threads:[~2007-02-12 12:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-12 12:51 Alexey Dobriyan [this message]
2007-02-12 21:36 ` utrace regressions (was: -mm merge plans for 2.6.21) Roland McGrath
2007-02-13 13:05 ` Alexey Dobriyan
2007-02-15 12:09 ` Alexey Dobriyan
2007-02-13 15:35 ` Alexey Dobriyan
2007-02-18 2:35 ` Roland McGrath
2007-02-21 13:37 ` Alexey Dobriyan
2007-03-07 9:10 ` Roland McGrath
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