Commit db6ccbb6 authored by Russell King's avatar Russell King Committed by Russell King

[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: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 4ac941d2
......@@ -436,7 +436,7 @@ __und_usr:
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 @@ __und_usr:
@
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 @@ __und_usr:
* 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 @@ do_fpe:
.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
......
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