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linux: improve exception-signal handling

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First, we use an alternate stack for signal handling now. The stack is
shared among all threads of the component, which is okay as we only
handle exceptions with log output and pass on to the default handler
(that terminates the execution). The primary motivation for the
alternate stack is the detection of SIGSEGV due to stack overflows.

Also, hybrid components now handle exception signals by logging and the
support for multi-threaded applications was improved.

Fixes #1935
This commit is contained in:
Christian Helmuth
2016-04-08 18:24:15 +02:00
parent 051e84c4b4
commit 14f1ac497e
5 changed files with 40 additions and 7 deletions
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9
repos/base-linux/src/lib/lx_hybrid/lx_hybrid.cc
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@ -50,8 +50,12 @@ int genode___cxa_atexit(void (*func)(void*), void *arg, void *dso)
extern char **environ;
extern char **lx_environ;
static char signal_stack[0x2000] __attribute__((aligned(0x1000)));
static void empty_signal_handler(int) { }
extern void lx_exception_signal_handlers();
/*
* This function must be called before any other static constructor in the Genode
* application, so it gets the highest priority (lowest priority number >100)
@ -60,6 +64,9 @@ __attribute__((constructor(101))) void lx_hybrid_init()
{
lx_environ = environ;
lx_sigaltstack(signal_stack, sizeof(signal_stack));
lx_exception_signal_handlers();
/*
* Set signal handler such that canceled system calls get not
* transparently retried after a signal gets received.
@ -348,6 +355,8 @@ Linux_cpu_session *cpu_session(Cpu_session * cpu_session)
static void adopt_thread(Native_thread::Meta_data *meta_data)
{
lx_sigaltstack(signal_stack, sizeof(signal_stack));
/*
* Set signal handler such that canceled system calls get not
* transparently retried after a signal gets received.