@@ -188,7 +188,7 @@ extern char __syscall_stub_start[];
/**
* userspace_tramp() - userspace trampoline
- * @stack: pointer to the new userspace stack page, can be NULL, if? FIXME:
+ * @stack: pointer to the new userspace stack page
*
* The userspace trampoline is used to setup a new userspace process in start_userspace() after it was clone()'ed.
* This function will run on a temporary stack page.
@@ -203,9 +203,13 @@ extern char __syscall_stub_start[];
*/
static int userspace_tramp(void *stack)
{
+ struct sigaction sa;
void *addr;
int fd;
unsigned long long offset;
+ unsigned long segv_handler = STUB_CODE +
+ (unsigned long) stub_segv_handler -
+ (unsigned long) __syscall_stub_start;
ptrace(PTRACE_TRACEME, 0, 0, 0);
@@ -221,34 +225,25 @@ static int userspace_tramp(void *stack)
exit(1);
}
- if (stack != NULL) {
- fd = phys_mapping(to_phys(stack), &offset);
- addr = mmap((void *) STUB_DATA,
- UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
- MAP_FIXED | MAP_SHARED, fd, offset);
- if (addr == MAP_FAILED) {
- printk(UM_KERN_ERR "mapping segfault stack at 0x%lx failed, errno = %d\n",
- STUB_DATA, errno);
- exit(1);
- }
+ fd = phys_mapping(to_phys(stack), &offset);
+ addr = mmap((void *) STUB_DATA,
+ UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
+ MAP_FIXED | MAP_SHARED, fd, offset);
+ if (addr == MAP_FAILED) {
+ printk(UM_KERN_ERR "mapping segfault stack at 0x%lx failed, errno = %d\n",
+ STUB_DATA, errno);
+ exit(1);
}
- if (stack != NULL) {
- struct sigaction sa;
-
- unsigned long v = STUB_CODE +
- (unsigned long) stub_segv_handler -
- (unsigned long) __syscall_stub_start;
-
- set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
- sigemptyset(&sa.sa_mask);
- sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
- sa.sa_sigaction = (void *) v;
- sa.sa_restorer = NULL;
- if (sigaction(SIGSEGV, &sa, NULL) < 0) {
- printk(UM_KERN_ERR "%s - setting SIGSEGV handler failed - errno = %d\n",
- __func__, errno);
- exit(1);
- }
+
+ set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
+ sigemptyset(&sa.sa_mask);
+ sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
+ sa.sa_sigaction = (void *) segv_handler;
+ sa.sa_restorer = NULL;
+ if (sigaction(SIGSEGV, &sa, NULL) < 0) {
+ printk(UM_KERN_ERR "%s - setting SIGSEGV handler failed - errno = %d\n",
+ __func__, errno);
+ exit(1);
}
kill(os_getpid(), SIGSTOP);
@@ -260,7 +255,7 @@ int kill_userspace_mm[NR_CPUS];
/**
* start_userspace() - prepare a new userspace process
- * @stub_stack: pointer to the stub stack. Can be NULL, if? FIXME:
+ * @stub_stack: pointer to the stub stack.
*
* Setups a new temporary stack page that is used while userspace_tramp() runs
* Clones the kernel process into a new userspace process, with FDs only.
start_userspace is only called from exactly one location, and the passed pointer for the userspace process stack cannot be NULL. Remove the check, without changing the control flow. Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net> --- arch/um/os-Linux/skas/process.c | 53 +++++++++++++++------------------ 1 file changed, 24 insertions(+), 29 deletions(-)