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MIPS: Hang if run on a secondary CPU

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Some systems are configured such that multiple CPUs begin running from
their reset vector following a system reset. If this occurs then U-Boot
will be run on multiple CPUs simultaneously, which causes all sorts of
issues as the multiple instances of U-Boot clobber each other.

Prevent this from happening by simply hanging with an infinite loop if
we run on a CPU whose ID, as determined by GlobalNumber or EBase.CPUNum
as appropriate, is non-zero.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This commit is contained in:
Paul Burton
2016-09-21 14:59:54 +01:00
committed by Daniel Schwierzeck
parent d263cda5ae
commit 31d36f748c
2 changed files with 27 additions and 1 deletions
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21
arch/mips/cpu/start.S
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@ -108,9 +108,28 @@ ENTRY(_start)
.align 4
reset:
#if __mips_isa_rev >= 6
mfc0 t0, CP0_CONFIG, 5
and t0, t0, MIPS_CONF5_VP
beqz t0, 1f
nop
b 2f
mfc0 t0, CP0_GLOBALNUMBER
#endif
1: mfc0 t0, CP0_EBASE
and t0, t0, EBASE_CPUNUM
/* Hang if this isn't the first CPU in the system */
2: beqz t0, 4f
nop
3: wait
b 3b
nop
/* Clear watch registers */
MTC0 zero, CP0_WATCHLO
4: MTC0 zero, CP0_WATCHLO
mtc0 zero, CP0_WATCHHI
/* WP(Watch Pending), SW0/1 should be cleared */