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Diffstat (limited to 'arch/um/os-Linux/start_up.c')
-rw-r--r--arch/um/os-Linux/start_up.c111
1 files changed, 18 insertions, 93 deletions
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index e3ee4db58b..8b0e98ab84 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -112,102 +112,32 @@ static int start_ptraced_child(void)
return pid;
}
-/* When testing for SYSEMU support, if it is one of the broken versions, we
- * must 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
- * must work anyway!
- */
-static int stop_ptraced_child(int pid, int exitcode, int mustexit)
+static void stop_ptraced_child(int pid, int exitcode)
{
- int status, n, ret = 0;
+ int status, n;
+
+ if (ptrace(PTRACE_CONT, pid, 0, 0) < 0)
+ fatal_perror("stop_ptraced_child : ptrace failed");
- if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) {
- perror("stop_ptraced_child : ptrace failed");
- return -1;
- }
CATCH_EINTR(n = waitpid(pid, &status, 0));
if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
int exit_with = WEXITSTATUS(status);
- if (exit_with == 2)
- non_fatal("check_ptrace : child exited with status 2. "
- "\nDisabling SYSEMU support.\n");
- non_fatal("check_ptrace : child exited with exitcode %d, while "
- "expecting %d; status 0x%x\n", exit_with,
- exitcode, status);
- if (mustexit)
- exit(1);
- ret = -1;
+ fatal("stop_ptraced_child : child exited with exitcode %d, "
+ "while expecting %d; status 0x%x\n", exit_with,
+ exitcode, status);
}
-
- return ret;
-}
-
-/* Changed only during early boot */
-static int force_sysemu_disabled = 0;
-
-static int __init nosysemu_cmd_param(char *str, int* add)
-{
- force_sysemu_disabled = 1;
- return 0;
}
-__uml_setup("nosysemu", nosysemu_cmd_param,
-"nosysemu\n"
-" Turns off syscall emulation patch for ptrace (SYSEMU).\n"
-" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
-" behaviour of ptrace() and helps reduce host context switch rates.\n"
-" To make it work, you need a kernel patch for your host, too.\n"
-" See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
-" information.\n\n");
-
static void __init check_sysemu(void)
{
- unsigned long regs[MAX_REG_NR];
int pid, n, status, count=0;
- os_info("Checking syscall emulation patch for ptrace...");
- sysemu_supported = 0;
- pid = start_ptraced_child();
-
- if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
- goto fail;
-
- CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
- if (n < 0)
- fatal_perror("check_sysemu : wait failed");
- if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
- fatal("check_sysemu : expected SIGTRAP, got status = %d\n",
- status);
-
- if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
- fatal_perror("check_sysemu : PTRACE_GETREGS failed");
- if (PT_SYSCALL_NR(regs) != __NR_getpid) {
- non_fatal("check_sysemu got system call number %d, "
- "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
- goto fail;
- }
-
- n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
- if (n < 0) {
- non_fatal("check_sysemu : failed to modify system call "
- "return");
- goto fail;
- }
-
- if (stop_ptraced_child(pid, 0, 0) < 0)
- goto fail_stopped;
-
- sysemu_supported = 1;
- os_info("OK\n");
- set_using_sysemu(!force_sysemu_disabled);
-
- os_info("Checking advanced syscall emulation patch for ptrace...");
+ os_info("Checking syscall emulation for ptrace...");
pid = start_ptraced_child();
- if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
+ if ((ptrace(PTRACE_SETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
- fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed");
+ fatal_perror("check_sysemu: PTRACE_SETOPTIONS failed");
while (1) {
count++;
@@ -240,20 +170,15 @@ static void __init check_sysemu(void)
goto fail;
}
}
- if (stop_ptraced_child(pid, 0, 0) < 0)
- goto fail_stopped;
+ stop_ptraced_child(pid, 0);
- sysemu_supported = 2;
os_info("OK\n");
- if (!force_sysemu_disabled)
- set_using_sysemu(sysemu_supported);
return;
fail:
- stop_ptraced_child(pid, 1, 0);
-fail_stopped:
- non_fatal("missing\n");
+ stop_ptraced_child(pid, 1);
+ fatal("missing\n");
}
static void __init check_ptrace(void)
@@ -263,9 +188,9 @@ static void __init check_ptrace(void)
os_info("Checking that ptrace can change system call numbers...");
pid = start_ptraced_child();
- if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
+ if ((ptrace(PTRACE_SETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
- fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
+ fatal_perror("check_ptrace: PTRACE_SETOPTIONS failed");
while (1) {
if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
@@ -291,7 +216,7 @@ static void __init check_ptrace(void)
break;
}
}
- stop_ptraced_child(pid, 0, 1);
+ stop_ptraced_child(pid, 0);
os_info("OK\n");
check_sysemu();
}
@@ -370,7 +295,7 @@ void __init os_early_checks(void)
pid = start_ptraced_child();
if (init_pid_registers(pid))
fatal("Failed to initialize default registers");
- stop_ptraced_child(pid, 1, 1);
+ stop_ptraced_child(pid, 1);
}
int __init parse_iomem(char *str, int *add)