This allows page faults to be delivered when they happen. Without this,
it can happen that a page fault will occur when SIGSEGV is disabled, and
the host will then just kill UML because it can't invoke the handler.
Signed-off-by: Jeff Dike <[email protected]>
Index: 2.6.9-rc2/arch/um/kernel/process.c
===================================================================
--- 2.6.9-rc2.orig/arch/um/kernel/process.c 2004-09-14 13:30:33.000000000 -0400
+++ 2.6.9-rc2/arch/um/kernel/process.c 2004-09-14 13:30:34.000000000 -0400
@@ -57,11 +57,7 @@
{
int flags = altstack ? SA_ONSTACK : 0;
- /* NODEFER is set here because SEGV isn't turned back on when the
- * handler is ready to receive signals. This causes any segfault
- * during a copy_user to kill the process because the fault is blocked.
- */
- set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags | SA_NODEFER,
+ set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags,
SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
Index: 2.6.9-rc2/arch/um/kernel/tt/trap_user.c
===================================================================
--- 2.6.9-rc2.orig/arch/um/kernel/tt/trap_user.c 2004-09-14 13:30:22.000000000 -0400
+++ 2.6.9-rc2/arch/um/kernel/tt/trap_user.c 2004-09-14 13:30:34.000000000 -0400
@@ -23,6 +23,13 @@
unprotect_kernel_mem();
+ /* This is done because to allow SIGSEGV to be delivered inside a SEGV
+ * handler. This can happen in copy_user, and if SEGV is disabled,
+ * the process will die.
+ */
+ if(sig == SIGSEGV)
+ change_sig(SIGSEGV, 1);
+
r = &TASK_REGS(get_current())->tt;
save_regs = *r;
is_user = user_context(SC_SP(sc));
More recent patches modify files in segv.