arm64: entry: handle debug exceptions in el*_inv

Currently we enable debug exceptions before reading ESR_EL1 in both
el0_inv and el1_inv. If a debug exception is taken before we read
ESR_EL1, the value will have been corrupted.

As el*_inv is typically fatal, an intervening debug exception results in
misleading debug information being logged to the console, but is not
otherwise harmful.

As with the other entry paths, we can use the ESR_EL1 value stashed
earlier in the exception entry (in x25 for el0_sync{,_compat}, and x1
for el1_sync), giving us better error reporting in this case.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index a7691a37866834375283b56501e6b11f23f49de8..f860bfda454afb9de7007684ba60eaf7f375e130 100644 (file)
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -352,8 +352,8 @@ el1_inv:
        // TODO: add support for undefined instructions in kernel mode
        enable_dbg
        mov     x0, sp
+       mov     x2, x1
        mov     x1, #BAD_SYNC
-       mrs     x2, esr_el1
        b       bad_mode
 ENDPROC(el1_sync)
 
@@ -553,7 +553,7 @@ el0_inv:
        ct_user_exit
        mov     x0, sp
        mov     x1, #BAD_SYNC
-       mrs     x2, esr_el1
+       mov     x2, x25
        bl      bad_mode
        b       ret_to_user
 ENDPROC(el0_sync)