ARM: smp_on_up: allow non-ARM SMP processors

Allow non-ARM SMP processors to use the SMP_ON_UP feature.  CPUs
supporting SMP must have the new CPU ID format, so check for this first.
Then check for ARM11MPCore, which fails the MPIDR check.  Lastly check
the MPIDR reports multiprocessing extensions and that the CPU is part of
a multiprocessing system.

Cc: <stable@kernel.org>
Reported-and-Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 10 insertions, 12 deletions

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index f17d9a09e8fb..c0225da3fb21 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -392,24 +392,22 @@ ENDPROC(__turn_mmu_on)
 
 #ifdef CONFIG_SMP_ON_UP
 __fixup_smp:
-        mov     r4, #0x00070000
-        orr     r3, r4, #0xff000000     @ mask 0xff070000
-        orr     r4, r4, #0x41000000     @ val 0x41070000
-        and     r0, r9, r3
-        teq     r0, r4                  @ ARM CPU and ARMv6/v7?
+        and     r3, r9, #0x000f0000     @ architecture version
+        teq     r3, #0x000f0000         @ CPU ID supported?
         bne     __fixup_smp_on_up       @ no, assume UP
 
-        orr     r3, r3, #0x0000ff00
-        orr     r3, r3, #0x000000f0     @ mask 0xff07fff0
+        bic     r3, r9, #0x00ff0000
+        bic     r3, r3, #0x0000000f     @ mask 0xff00fff0
+        mov     r4, #0x41000000
         orr     r4, r4, #0x0000b000
-        orr     r4, r4, #0x00000020     @ val 0x4107b020
-        and     r0, r9, r3
-        teq     r0, r4                  @ ARM 11MPCore?
+        orr     r4, r4, #0x00000020     @ val 0x4100b020
+        teq     r3, r4                  @ ARM 11MPCore?
         moveq   pc, lr                  @ yes, assume SMP
 
         mrc     p15, 0, r0, c0, c0, 5   @ read MPIDR
-        tst     r0, #1 << 31
-        movne   pc, lr                  @ bit 31 => SMP
+        and     r0, r0, #0xc0000000     @ multiprocessing extensions and
+        teq     r0, #0x80000000         @ not part of a uniprocessor system?
+        moveq   pc, lr                  @ yes, assume SMP
 
 __fixup_smp_on_up:
         adr     r0, 1f