[ARM] Fix kernel-mode undefined instruction aborts
If the kernel attempts to execute a CP1 or CP2 instruction and it
aborts, and a FP emulator is not loaded, we try to return as if to
a user context, instead of the proper kernel context. Since the
fault came from kernel mode, we must use the kernel return paths.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 2db42b1..8517c3c 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -436,7 +436,7 @@
usr_entry
tst r3, #PSR_T_BIT @ Thumb mode?
- bne fpundefinstr @ ignore FP
+ bne __und_usr_unknown @ ignore FP
sub r4, r2, #4
@
@@ -448,7 +448,7 @@
@
1: ldrt r0, [r4]
adr r9, ret_from_exception
- adr lr, fpundefinstr
+ adr lr, __und_usr_unknown
@
@ fallthrough to call_fpe
@
@@ -476,7 +476,9 @@
* Emulators may wish to make use of the following registers:
* r0 = instruction opcode.
* r2 = PC+4
+ * r9 = normal "successful" return address
* r10 = this threads thread_info structure.
+ * lr = unrecognised instruction return address
*/
call_fpe:
tst r0, #0x08000000 @ only CDP/CPRT/LDC/STC have bit 27
@@ -545,10 +547,12 @@
.data
ENTRY(fp_enter)
- .word fpundefinstr
+ .word no_fp
.text
-fpundefinstr:
+no_fp: mov pc, lr
+
+__und_usr_unknown:
mov r0, sp
adr lr, ret_from_exception
b do_undefinstr