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[PATCH] uml: use fork instead of clone

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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@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeff Dike 2005-06-13 15:52:14 -07:00 committed by Linus Torvalds
parent 36ca1195ad
commit 98fdffccea
1 changed files with 19 additions and 29 deletions
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48
arch/um/kernel/process.c
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@ -130,7 +130,7 @@ int start_fork_tramp(void *thread_arg, unsigned long temp_stack,
return(arg.pid); return(arg.pid);
} }
static int ptrace_child(void *arg) static int ptrace_child(void)
{ {
int ret; int ret;
int pid = os_getpid(), ppid = getppid(); int pid = os_getpid(), ppid = getppid();
@ -159,20 +159,16 @@ static int ptrace_child(void *arg)
_exit(ret); _exit(ret);
} }
static int start_ptraced_child(void **stack_out) static int start_ptraced_child(void)
{ {
void *stack;
unsigned long sp;
int pid, n, status; int pid, n, status;
stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, pid = fork();
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if(pid == 0)
if(stack == MAP_FAILED) ptrace_child();
panic("check_ptrace : mmap failed, errno = %d", errno);
sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
if(pid < 0) if(pid < 0)
panic("check_ptrace : clone failed, errno = %d", errno); panic("check_ptrace : fork failed, errno = %d", errno);
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0) if(n < 0)
panic("check_ptrace : wait failed, errno = %d", errno); panic("check_ptrace : wait failed, errno = %d", errno);
@ -180,7 +176,6 @@ static int start_ptraced_child(void **stack_out)
panic("check_ptrace : expected SIGSTOP, got status = %d", panic("check_ptrace : expected SIGSTOP, got status = %d",
status); status);
*stack_out = stack;
return(pid); return(pid);
} }
@ -188,12 +183,12 @@ static int start_ptraced_child(void **stack_out)
* just avoid using sysemu, not panic, but only if SYSEMU features are broken. * just avoid using sysemu, not panic, but only if SYSEMU features are broken.
* So only for SYSEMU features we test mustpanic, while normal host features * So only for SYSEMU features we test mustpanic, while normal host features
* must work anyway!*/ * must work anyway!*/
static int stop_ptraced_child(int pid, void *stack, int exitcode, int mustpanic) static int stop_ptraced_child(int pid, int exitcode, int mustexit)
{ {
int status, n, ret = 0; int status, n, ret = 0;
if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
panic("check_ptrace : ptrace failed, errno = %d", errno); panic("stop_ptraced_child : ptrace failed, errno = %d", errno);
CATCH_EINTR(n = waitpid(pid, &status, 0)); CATCH_EINTR(n = waitpid(pid, &status, 0));
if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
int exit_with = WEXITSTATUS(status); int exit_with = WEXITSTATUS(status);
@ -204,15 +199,13 @@ static int stop_ptraced_child(int pid, void *stack, int exitcode, int mustpanic)
printk("check_ptrace : child exited with exitcode %d, while " printk("check_ptrace : child exited with exitcode %d, while "
"expecting %d; status 0x%x", exit_with, "expecting %d; status 0x%x", exit_with,
exitcode, status); exitcode, status);
if (mustpanic) if (mustexit)
panic("\n"); panic("\n");
else else
printk("\n"); printk("\n");
ret = -1; ret = -1;
} }
if(munmap(stack, PAGE_SIZE) < 0)
panic("check_ptrace : munmap failed, errno = %d", errno);
return ret; return ret;
} }
@ -234,12 +227,11 @@ __uml_setup("nosysemu", nosysemu_cmd_param,
static void __init check_sysemu(void) static void __init check_sysemu(void)
{ {
void *stack;
int pid, syscall, n, status, count=0; int pid, syscall, n, status, count=0;
printk("Checking syscall emulation patch for ptrace..."); printk("Checking syscall emulation patch for ptrace...");
sysemu_supported = 0; sysemu_supported = 0;
pid = start_ptraced_child(&stack); pid = start_ptraced_child();
if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
goto fail; goto fail;
@ -257,7 +249,7 @@ static void __init check_sysemu(void)
panic("check_sysemu : failed to modify system " panic("check_sysemu : failed to modify system "
"call return, errno = %d", errno); "call return, errno = %d", errno);
if (stop_ptraced_child(pid, stack, 0, 0) < 0) if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped; goto fail_stopped;
sysemu_supported = 1; sysemu_supported = 1;
@ -265,7 +257,7 @@ static void __init check_sysemu(void)
set_using_sysemu(!force_sysemu_disabled); set_using_sysemu(!force_sysemu_disabled);
printk("Checking advanced syscall emulation patch for ptrace..."); printk("Checking advanced syscall emulation patch for ptrace...");
pid = start_ptraced_child(&stack); pid = start_ptraced_child();
while(1){ while(1){
count++; count++;
if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
@ -290,7 +282,7 @@ static void __init check_sysemu(void)
break; break;
} }
} }
if (stop_ptraced_child(pid, stack, 0, 0) < 0) if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped; goto fail_stopped;
sysemu_supported = 2; sysemu_supported = 2;
@ -301,18 +293,17 @@ static void __init check_sysemu(void)
return; return;
fail: fail:
stop_ptraced_child(pid, stack, 1, 0); stop_ptraced_child(pid, 1, 0);
fail_stopped: fail_stopped:
printk("missing\n"); printk("missing\n");
} }
void __init check_ptrace(void) void __init check_ptrace(void)
{ {
void *stack;
int pid, syscall, n, status; int pid, syscall, n, status;
printk("Checking that ptrace can change system call numbers..."); printk("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) if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno); panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno);
@ -339,7 +330,7 @@ void __init check_ptrace(void)
break; break;
} }
} }
stop_ptraced_child(pid, stack, 0, 1); stop_ptraced_child(pid, 0, 1);
printk("OK\n"); printk("OK\n");
check_sysemu(); check_sysemu();
} }
@ -371,11 +362,10 @@ void forward_pending_sigio(int target)
static inline int check_skas3_ptrace_support(void) static inline int check_skas3_ptrace_support(void)
{ {
struct ptrace_faultinfo fi; struct ptrace_faultinfo fi;
void *stack;
int pid, n, ret = 1; int pid, n, ret = 1;
printf("Checking for the skas3 patch in the host..."); printf("Checking for the skas3 patch in the host...");
pid = start_ptraced_child(&stack); pid = start_ptraced_child();
n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
if (n < 0) { if (n < 0) {
@ -390,7 +380,7 @@ static inline int check_skas3_ptrace_support(void)
} }
init_registers(pid); init_registers(pid);
stop_ptraced_child(pid, stack, 1, 1); stop_ptraced_child(pid, 1, 1);
return(ret); return(ret);
} }