On Wed, 2010-06-02 at 19:19 +0200, Jan Kiszka wrote:
Hi all,
here is the first apparently working prototype for getting hold of
endless user space loops in RT threads. A simple test case of mine now
receive a SIGDEBUG even if it does while (1);.
The design follows Gilles' suggestion to force a SEGV on victim thread
but restore the patched PC before migrating the thread after this fault.
The only drawback of this approach: We need to keep track of the
preempted register set at I-pipe level. I basically replicated what
Linux does these days as well and exported it as ipipe_get_irq_regs()
(the second patch).
This is an x86-64-only draft which clearly needs more love. I'm open for
suggestions of different abstractions wherever you see a need.
What if you have no MMU ?
Jan
---
include/asm-generic/hal.h|2 ++
include/asm-x86/bits/thread_64.h |1 +
include/asm-x86/system_64.h | 26 ++
ksrc/nucleus/pod.c |5 +
ksrc/nucleus/sched.c |1 +
5 files changed, 35 insertions(+), 0 deletions(-)
diff --git a/include/asm-generic/hal.h b/include/asm-generic/hal.h
index 84c1a4d..be6abf0 100644
--- a/include/asm-generic/hal.h
+++ b/include/asm-generic/hal.h
@@ -96,6 +96,8 @@ typedef spinlock_t rthal_spinlock_t;
#define rthal_irq_cookie(ipd,irq)__ipipe_irq_cookie(ipd,irq)
#define rthal_irq_handler(ipd,irq) __ipipe_irq_handler(ipd,irq)
+#define rthal_get_irq_regs() ipipe_get_irq_regs()
+
#define rthal_cpudata_irq_hits(ipd,cpu,irq)
__ipipe_cpudata_irq_hits(ipd,cpu,irq)
#ifndef local_irq_save_hw_smp
diff --git a/include/asm-x86/bits/thread_64.h
b/include/asm-x86/bits/thread_64.h
index 91b71ed..d163c9e 100644
--- a/include/asm-x86/bits/thread_64.h
+++ b/include/asm-x86/bits/thread_64.h
@@ -33,6 +33,7 @@ static inline void xnarch_init_tcb(xnarchtcb_t * tcb)
tcb-ripp = tcb-rip;
tcb-fpup = tcb-i387;
tcb-is_root = 0;
+ tcb-forced_um_exit = 0;
/* Must be followed by xnarch_init_thread(). */
}
diff --git a/include/asm-x86/system_64.h b/include/asm-x86/system_64.h
index 4de8693..f023dab 100644
--- a/include/asm-x86/system_64.h
+++ b/include/asm-x86/system_64.h
@@ -60,6 +60,8 @@ typedef struct xnarchtcb { /* Per-thread
arch-dependent block */
unsigned long ts_usedfpu: 1;
unsigned long cr0_ts: 1;
+ unsigned long forced_um_exit: 1;
+
unsigned stacksize; /* Aligned size of stack (bytes) */
unsigned long *stackbase; /* Stack space */
@@ -122,6 +124,30 @@ static inline void xnarch_free_stack_mem(void *chunk,
u_long bytes)
kfree(chunk);
}
+static inline void xnarch_force_userspace_exit(xnarchtcb_t *tcb)
+{
+ struct pt_regs *regs = rthal_get_irq_regs();
+
+ if (user_mode(regs)) {
+ tcb-rip = regs-x86reg_ip;
+ tcb-forced_um_exit = 1;
+ regs-x86reg_ip = 0;
+ }
+}
+
+static inline int
+xnarch_fixup_userspace_exit(xnarchtcb_t *tcb, xnarch_fltinfo_t *fi)
+{
+#ifdef CONFIG_XENO_OPT_PERVASIVE
+ if (tcb-forced_um_exit) {
+ fi-regs-x86reg_ip = tcb-rip;
+ tcb-forced_um_exit = 0;
+ return 1;
+ }
+#endif /* CONFIG_XENO_OPT_PERVASIVE */
+ return 0;
+}
+
#ifdef __cplusplus
}
#endif
diff --git a/ksrc/nucleus/pod.c b/ksrc/nucleus/pod.c
index 7002a73..bdb5758 100644
--- a/ksrc/nucleus/pod.c
+++ b/ksrc/nucleus/pod.c
@@ -2547,6 +2547,11 @@ int xnpod_trap_fault(xnarch_fltinfo_t *fltinfo)
thread = xnpod_current_thread();
+ if (xnarch_fixup_userspace_exit(xnthread_archtcb(thread), fltinfo)) {
+ xnshadow_relax(0, 0);
+ return 1;
+ }
+
trace_mark(xn_nucleus, thread_fault,
thread %p thread_name %s ip %p type %d,
thread, xnthread_name(thread),
diff --git a/ksrc/nucleus/sched.c b/ksrc/nucleus/sched.c
index 0b737a3..64fa0e0 100644
--- a/ksrc/nucleus/sched.c
+++ b/ksrc/nucleus/sched.c
@@ -100,6 +100,7 @@ static void xnsched_watchdog_handler(struct xntimer
*timer)
'%s'\n, xnthread_name(thread));
xnthread_set_info(thread, XNAMOK | XNKICKED);
xnshadow_send_sig(thread, SIGDEBUG, SIGDEBUG_WATCHDOG, 1);
+ xnarch_force_userspace_exit(xnthread_archtcb(thread));
} else
#endif /* CONFIG_XENO_OPT_PERVASIVE */
{
--
Philippe.
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