From 31d36f748c52b22833aa946f6c406cc8fb2f1908 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Wed, 21 Sep 2016 14:59:54 +0100 Subject: [PATCH] MIPS: Hang if run on a secondary CPU 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 --- arch/mips/cpu/start.S | 21 ++++++++++++++++++++- arch/mips/include/asm/mipsregs.h | 7 +++++++ 2 files changed, 27 insertions(+), 1 deletion(-) diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S index cbc02fa9fe..3f0fc12547 100644 --- a/arch/mips/cpu/start.S +++ b/arch/mips/cpu/start.S @@ -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 */ diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h index b4c2dff483..9ab506361e 100644 --- a/arch/mips/include/asm/mipsregs.h +++ b/arch/mips/include/asm/mipsregs.h @@ -39,6 +39,7 @@ #define CP0_ENTRYLO0 $2 #define CP0_ENTRYLO1 $3 #define CP0_CONF $3 +#define CP0_GLOBALNUMBER $3, 1 #define CP0_CONTEXT $4 #define CP0_PAGEMASK $5 #define CP0_WIRED $6 @@ -360,6 +361,11 @@ #define CAUSEB_BD 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. */ @@ -553,6 +559,7 @@ #define MIPS_CONF5_MRP (_ULCAST_(1) << 3) #define MIPS_CONF5_LLB (_ULCAST_(1) << 4) #define MIPS_CONF5_MVH (_ULCAST_(1) << 5) +#define MIPS_CONF5_VP (_ULCAST_(1) << 7) #define MIPS_CONF5_FRE (_ULCAST_(1) << 8) #define MIPS_CONF5_UFE (_ULCAST_(1) << 9) #define MIPS_CONF5_L2C (_ULCAST_(1) << 10) -- 2.30.2