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Message-ID: <20070814214027.GA17549@c2.user-mode-linux.org>
Date: Tue, 14 Aug 2007 17:40:27 -0400
From: Jeff Dike <jdike@...toit.com>
To: Andrew Morton <akpm@...l.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
uml-devel <user-mode-linux-devel@...ts.sourceforge.net>
Subject: [PATCH 14/14] UML - Replace clone with fork
Convert the boot-time host ptrace testing from clone to fork. They were
essentially doing fork anyway. This cleans up the code a bit, and makes
valgrind a bit happier about grinding it.
Signed-off-by: Jeff Dike <jdike@...ux.intel.com>
--
arch/um/os-Linux/start_up.c | 55 ++++++++++++++++----------------------------
1 file changed, 20 insertions(+), 35 deletions(-)
Index: linux-2.6.22/arch/um/os-Linux/start_up.c
===================================================================
--- linux-2.6.22.orig/arch/um/os-Linux/start_up.c 2007-08-10 15:59:56.000000000 -0400
+++ linux-2.6.22/arch/um/os-Linux/start_up.c 2007-08-10 16:16:32.000000000 -0400
@@ -25,7 +25,7 @@
#include "registers.h"
#include "skas_ptrace.h"
-static int ptrace_child(void *arg)
+static int ptrace_child(void)
{
int ret;
int pid = os_getpid(), ppid = getppid();
@@ -90,31 +90,23 @@ static void non_fatal(char *fmt, ...)
fflush(stdout);
}
-static int start_ptraced_child(void **stack_out)
+static int start_ptraced_child(void)
{
- void *stack;
- unsigned long sp;
int pid, n, status;
- stack = mmap(NULL, UM_KERN_PAGE_SIZE,
- PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- if (stack == MAP_FAILED)
- fatal_perror("check_ptrace : mmap failed");
-
- sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
- pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
- if (pid < 0)
- fatal_perror("start_ptraced_child : clone failed");
+ pid = fork();
+ if (pid == 0)
+ ptrace_child();
+ else if (pid < 0)
+ fatal_perror("start_ptraced_child : fork failed");
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
- fatal_perror("check_ptrace : clone failed");
+ fatal_perror("check_ptrace : waitpid failed");
if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
fatal("check_ptrace : expected SIGSTOP, got status = %d",
status);
- *stack_out = stack;
return pid;
}
@@ -124,8 +116,7 @@ static int start_ptraced_child(void **st
* So only for SYSEMU features we test mustpanic, while normal host features
* must work anyway!
*/
-static int stop_ptraced_child(int pid, void *stack, int exitcode,
- int mustexit)
+static int stop_ptraced_child(int pid, int exitcode, int mustexit)
{
int status, n, ret = 0;
@@ -145,8 +136,6 @@ static int stop_ptraced_child(int pid, v
ret = -1;
}
- if (munmap(stack, UM_KERN_PAGE_SIZE) < 0)
- fatal_perror("check_ptrace : munmap failed");
return ret;
}
@@ -198,13 +187,12 @@ __uml_setup("nosysemu", nosysemu_cmd_par
static void __init check_sysemu(void)
{
- void *stack;
unsigned long regs[MAX_REG_NR];
int pid, n, status, count=0;
non_fatal("Checking syscall emulation patch for ptrace...");
sysemu_supported = 0;
- pid = start_ptraced_child(&stack);
+ pid = start_ptraced_child();
if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
goto fail;
@@ -231,7 +219,7 @@ static void __init check_sysemu(void)
goto fail;
}
- if (stop_ptraced_child(pid, stack, 0, 0) < 0)
+ if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 1;
@@ -239,7 +227,7 @@ static void __init check_sysemu(void)
set_using_sysemu(!force_sysemu_disabled);
non_fatal("Checking advanced syscall emulation patch for ptrace...");
- pid = start_ptraced_child(&stack);
+ pid = start_ptraced_child();
if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
@@ -271,7 +259,7 @@ static void __init check_sysemu(void)
fatal("check_ptrace : expected SIGTRAP or "
"(SIGTRAP | 0x80), got status = %d", status);
}
- if (stop_ptraced_child(pid, stack, 0, 0) < 0)
+ if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 2;
@@ -282,18 +270,17 @@ static void __init check_sysemu(void)
return;
fail:
- stop_ptraced_child(pid, stack, 1, 0);
+ stop_ptraced_child(pid, 1, 0);
fail_stopped:
non_fatal("missing\n");
}
static void __init check_ptrace(void)
{
- void *stack;
int pid, syscall, n, status;
non_fatal("Checking that ptrace can change system call numbers...");
- pid = start_ptraced_child(&stack);
+ pid = start_ptraced_child();
if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
@@ -323,7 +310,7 @@ static void __init check_ptrace(void)
break;
}
}
- stop_ptraced_child(pid, stack, 0, 1);
+ stop_ptraced_child(pid, 0, 1);
non_fatal("OK\n");
check_sysemu();
}
@@ -403,11 +390,10 @@ __uml_setup("noptraceldt", noptraceldt_c
static inline void check_skas3_ptrace_faultinfo(void)
{
struct ptrace_faultinfo fi;
- void *stack;
int pid, n;
non_fatal(" - PTRACE_FAULTINFO...");
- pid = start_ptraced_child(&stack);
+ pid = start_ptraced_child();
n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
if (n < 0) {
@@ -425,13 +411,12 @@ static inline void check_skas3_ptrace_fa
}
init_registers(pid);
- stop_ptraced_child(pid, stack, 1, 1);
+ stop_ptraced_child(pid, 1, 1);
}
static inline void check_skas3_ptrace_ldt(void)
{
#ifdef PTRACE_LDT
- void *stack;
int pid, n;
unsigned char ldtbuf[40];
struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
@@ -440,7 +425,7 @@ static inline void check_skas3_ptrace_ld
.bytecount = sizeof(ldtbuf)};
non_fatal(" - PTRACE_LDT...");
- pid = start_ptraced_child(&stack);
+ pid = start_ptraced_child();
n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
if (n < 0) {
@@ -458,7 +443,7 @@ static inline void check_skas3_ptrace_ld
non_fatal("found, but use is disabled\n");
}
- stop_ptraced_child(pid, stack, 1, 1);
+ stop_ptraced_child(pid, 1, 1);
#else
/* PTRACE_LDT might be disabled via cmdline option.
* We want to override this, else we might use the stub
-
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