lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[ARM] Fix kernel-mode undefined instruction aborts

Browse Source 
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>
This commit is contained in:
Russell King
2007-01-06 22:53:48 +00:00
committed by Russell King
parent 4ac941d2d0
commit db6ccbb61c
1 changed files with 8 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
arch/arm/kernel/entry-armv.S
View File

@@ -436,7 +436,7 @@ __und_usr:
usr_entry usr_entry
tst r3, #PSR_T_BIT @ Thumb mode? tst r3, #PSR_T_BIT @ Thumb mode?
bne fpundefinstr @ ignore FP bne __und_usr_unknown @ ignore FP
sub r4, r2, #4 sub r4, r2, #4
@ @
@@ -448,7 +448,7 @@ __und_usr:
@ @
1: ldrt r0, [r4] 1: ldrt r0, [r4]
adr r9, ret_from_exception adr r9, ret_from_exception
adr lr, fpundefinstr adr lr, __und_usr_unknown
@ @
@ fallthrough to call_fpe @ fallthrough to call_fpe
@ @
@@ -476,7 +476,9 @@ __und_usr:
* Emulators may wish to make use of the following registers: * Emulators may wish to make use of the following registers:
* r0 = instruction opcode. * r0 = instruction opcode.
* r2 = PC+4 * r2 = PC+4
* r9 = normal "successful" return address
* r10 = this threads thread_info structure. * r10 = this threads thread_info structure.
* lr = unrecognised instruction return address
*/ */
call_fpe: call_fpe:
tst r0, #0x08000000 @ only CDP/CPRT/LDC/STC have bit 27 tst r0, #0x08000000 @ only CDP/CPRT/LDC/STC have bit 27
@@ -545,10 +547,12 @@ do_fpe:
.data .data
ENTRY(fp_enter) ENTRY(fp_enter)
.word fpundefinstr .word no_fp
.text .text
fpundefinstr: no_fp: mov pc, lr
__und_usr_unknown:
mov r0, sp mov r0, sp
adr lr, ret_from_exception adr lr, ret_from_exception
b do_undefinstr b do_undefinstr