[Xen-devel] [PATCH v2] xen/arm: Init traps very early

[Julien Grall <julien.grall@xxxxxxxxxx>]

The function init_traps setups the handler taken when Xen hits a BUG_ON/ASSERT.

If an error happen before init_traps is called, we loose the backtrace.

When a trap is taken from HYP mode, we need to:
    - get the processor ID, percpu has to be initialized and the
smp_processor_id correctly set.
    - initialize current, even tho it's not used for the time being. Move the
    debug sanity ealier.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Tested-by: Naresh Bhat <naresh.bhat@xxxxxxxxxx>

---
    Changes in v2:
        - Update a comment in the code to explain why we need to be set
        early.
        - Move the call after smp_processor_id as it's requires to be
        there.
        - Move set_current(...) ealier
---
 xen/arch/arm/setup.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index b9ce7a9..8c505cb 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -670,6 +670,12 @@ void __init start_xen(unsigned long boot_phys_offset,
     percpu_init_areas();
     set_processor_id(0); /* needed early, for smp_processor_id() */
 
+    set_current((struct vcpu *)0xfffff000); /* debug sanity */
+    idle_vcpu[0] = current;
+
+    /* Initialize traps early allow us to get backtrace when an error occured 
*/
+    init_traps();
+
     smp_clear_cpu_maps();
 
     /* This is mapped by head.S */
@@ -706,11 +712,6 @@ void __init start_xen(unsigned long boot_phys_offset,
 
     gic_init();
 
-    set_current((struct vcpu *)0xfffff000); /* debug sanity */
-    idle_vcpu[0] = current;
-
-    init_traps();
-
     setup_virt_paging();
 
     p2m_vmid_allocator_init();
-- 
1.7.10.4


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