[Xen-devel] [PATCH 3/3] xen/arm: Don't crash the domain on invalid HVC immediate

[Julien Grall <julien.grall@xxxxxxx>]

domain_crash_synchronous() should only be used when something went wrong
in Xen. It is better to inject to the guest as it will be in better
position to provide helpful information (stack trace...).

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>

---

    We potentially want to return -1 instead. This would make Xen more
    future-proof if we decide to implement the other HVC immediate.
---
 xen/arch/arm/traps.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 843adf4959..18da45dff3 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1473,14 +1473,17 @@ static void do_debug_trap(struct cpu_user_regs *regs, 
unsigned int code)
 #endif
 
 static void do_trap_hypercall(struct cpu_user_regs *regs, register_t *nr,
-                              unsigned long iss)
+                              const union hsr hsr)
 {
     arm_hypercall_fn_t call = NULL;
 
     BUILD_BUG_ON(NR_hypercalls < ARRAY_SIZE(arm_hypercall_table) );
 
-    if ( iss != XEN_HYPERCALL_TAG )
-        domain_crash_synchronous();
+    if ( hsr.iss != XEN_HYPERCALL_TAG )
+    {
+        gprintk(XENLOG_WARNING, "Invalid HVC imm 0x%x\n", hsr.iss);
+        return inject_undef_exception(regs, hsr);
+    }
 
     if ( *nr >= ARRAY_SIZE(arm_hypercall_table) )
     {
@@ -2150,7 +2153,7 @@ void do_trap_guest_sync(struct cpu_user_regs *regs)
         if ( hsr.iss == 0 )
             return do_trap_hvc_smccc(regs);
         nr = regs->r12;
-        do_trap_hypercall(regs, &nr, hsr.iss);
+        do_trap_hypercall(regs, &nr, hsr);
         regs->r12 = (uint32_t)nr;
         break;
     }
@@ -2164,7 +2167,7 @@ void do_trap_guest_sync(struct cpu_user_regs *regs)
 #endif
         if ( hsr.iss == 0 )
             return do_trap_hvc_smccc(regs);
-        do_trap_hypercall(regs, &regs->x16, hsr.iss);
+        do_trap_hypercall(regs, &regs->x16, hsr);
         break;
     case HSR_EC_SMC64:
         /*
-- 
2.11.0


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