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Re: [Xen-devel] [PATCH 14/27] xen/arm: traps: Improve logging for data/prefetch abort fault





On 08/22/2017 06:20 PM, Andre Przywara wrote:
Hi,

Hi Andre,


On 14/08/17 15:24, Julien Grall wrote:
Walk the hypervisor page table for data/prefetch abort fault to help
diagnostics error in the page tables.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
  xen/arch/arm/traps.c | 19 +++++++++++++++++++
  1 file changed, 19 insertions(+)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 819bdbc69e..dac4e54fa7 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2967,7 +2967,26 @@ asmlinkage void do_trap_hyp_sync(struct cpu_user_regs 
*regs)
          do_trap_brk(regs, hsr);
          break;
  #endif
+    case HSR_EC_DATA_ABORT_CURR_EL:
+    case HSR_EC_INSTR_ABORT_CURR_EL:
+    {
+        bool is_data = (hsr.ec == HSR_EC_DATA_ABORT_CURR_EL);
+        const char *fault = (is_data) ? "Data Abort" : "Instruction Abort";
+
+        printk("%s Trap. Syndrome=%#x\n", fault, hsr.iss);
+        /*
+         * FAR may not be valid for a Synchronous External abort other
+         * than translation table walk.
+         */
+        if ( hsr.xabt.fsc != FSC_SEA || !hsr.xabt.fnv )

This is quite hard to read. Would the DeMorgan'ed version be better?
           if ( hsr.xabt.fsc == FSC_SEA && hsr.xabt.fnv )
               printk ....
            else
               dump_hyp_walk ...

Indeed it is better. I will use that.

Cheers,


+            dump_hyp_walk(get_hfar(is_data));
+        else
+            printk("Invalid FAR, don't walk the hypervisor tables\n");

Nit: "not walking" sounds less ambiguous.

+        do_unexpected_trap(fault, regs);
+ break;
+    }
      default:
          printk("Hypervisor Trap. HSR=0x%x EC=0x%x IL=%x 
Syndrome=0x%"PRIx32"\n",
                 hsr.bits, hsr.ec, hsr.len, hsr.iss);

Ignoring the nits above:

I will fix both and keep the reviewed-by if you don't mind.

Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>

Cheers,

--
Julien Grall

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