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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
View file

@ -108,9 +108,28 @@ ENTRY(_start)
.align 4 .align 4
reset: 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 */ /* Clear watch registers */
MTC0 zero, CP0_WATCHLO 4: MTC0 zero, CP0_WATCHLO
mtc0 zero, CP0_WATCHHI mtc0 zero, CP0_WATCHHI
/* WP(Watch Pending), SW0/1 should be cleared */ /* WP(Watch Pending), SW0/1 should be cleared */

7
arch/mips/include/asm/mipsregs.h
View file

@ -39,6 +39,7 @@
#define CP0_ENTRYLO0 $2 #define CP0_ENTRYLO0 $2
#define CP0_ENTRYLO1 $3 #define CP0_ENTRYLO1 $3
#define CP0_CONF $3 #define CP0_CONF $3
#define CP0_GLOBALNUMBER $3, 1
#define CP0_CONTEXT $4 #define CP0_CONTEXT $4
#define CP0_PAGEMASK $5 #define CP0_PAGEMASK $5
#define CP0_WIRED $6 #define CP0_WIRED $6
@ -360,6 +361,11 @@
#define CAUSEB_BD 31 #define CAUSEB_BD 31
#define CAUSEF_BD (_ULCAST_(1) << 31) #define CAUSEF_BD (_ULCAST_(1) << 31)
/*
* Bits in the coprocessor 0 EBase register.
*/
#define EBASE_CPUNUM 0x3ff
/* /*
* Bits in the coprocessor 0 config register. * Bits in the coprocessor 0 config register.
*/ */
@ -553,6 +559,7 @@
#define MIPS_CONF5_MRP (_ULCAST_(1) << 3) #define MIPS_CONF5_MRP (_ULCAST_(1) << 3)
#define MIPS_CONF5_LLB (_ULCAST_(1) << 4) #define MIPS_CONF5_LLB (_ULCAST_(1) << 4)
#define MIPS_CONF5_MVH (_ULCAST_(1) << 5) #define MIPS_CONF5_MVH (_ULCAST_(1) << 5)
#define MIPS_CONF5_VP (_ULCAST_(1) << 7)
#define MIPS_CONF5_FRE (_ULCAST_(1) << 8) #define MIPS_CONF5_FRE (_ULCAST_(1) << 8)
#define MIPS_CONF5_UFE (_ULCAST_(1) << 9) #define MIPS_CONF5_UFE (_ULCAST_(1) << 9)
#define MIPS_CONF5_L2C (_ULCAST_(1) << 10) #define MIPS_CONF5_L2C (_ULCAST_(1) << 10)