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authorRussell King <rmk@dyn-67.arm.linux.org.uk>2007-01-06 22:53:48 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2007-01-06 22:53:48 +0000
commitdb6ccbb61c1291c8aaefadcc8304444f27eeb88d (patch)
tree196718a54ccd89fe12c48383a15e0639f8ddf939 /arch/arm/kernel
parent4ac941d2d04ef26a91adf677f3a371818596305d (diff)
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[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>
Diffstat (limited to 'arch/arm/kernel')
-rw-r--r--arch/arm/kernel/entry-armv.S12
1 files changed, 8 insertions, 4 deletions
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 @@ __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