Messages in this thread | | | Date | Sat, 7 Jan 2017 17:38:32 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH WIP 4/4] ARM: remove compile time vector base for CP15 case |
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On Sat, Jan 07, 2017 at 10:52:28PM +0530, afzal mohammed wrote: > vectors base is now dynamically updated for Hivecs as well as for > REMAP_VECTORS_TO_RAM case to DRAM_START. Hence remove these CP15 > cases. > > TODO: > Kill off VECTORS_BASE completely - this would require to handle MMU > case as well as ARM_MPU scenario dynamically.
Why do you think MMU doesn't already handle it?
> config VECTORS_BASE > hex > - default 0xffff0000 if MMU || CPU_HIGH_VECTOR > - default DRAM_BASE if REMAP_VECTORS_TO_RAM > + default 0xffff0000 if MMU > default 0x00000000
When MMU=y, the resulting VECTORS_BASE is always 0xffff0000. The only case where this ends up zero after your change is when MMU=n.
In any case here's the places it's used:
For nommu: arch/arm/kernel/head-nommu.S: mov r0, #CONFIG_VECTORS_BASE @ Cover from VECTORS_BASE arch/arm/kernel/head-nommu.S: setup_region r0, r5, r6, MPU_DATA_SIDE @ VECTORS_BASE, PL0 NA, enabled arch/arm/kernel/head-nommu.S: setup_region r0, r5, r6, MPU_INSTR_SIDE @ VECTORS_BASE, PL0 NA, enabled arch/arm/mm/nommu.c: memblock_reserve(CONFIG_VECTORS_BASE, 2 * PAGE_SIZE); arch/arm/mm/nommu.c: early_trap_init((void *)CONFIG_VECTORS_BASE);
To intercept the reset vector for secondary CPUs (because we hide it away from platforms, so platforms end up hacking around to get at it.) arch/arm/mach-berlin/platsmp.c: vectors_base = ioremap(CONFIG_VECTORS_BASE, SZ_32K);
For printing: arch/arm/mm/init.c: MLK(UL(CONFIG_VECTORS_BASE), UL(CONFIG_VECTORS_BASE) +
For dumping the page tables (but since this is only built for MMU=y, we know what CONFIG_VECTORS_BASE is here.) arch/arm/mm/dump.c: { CONFIG_VECTORS_BASE, "Vectors" }, arch/arm/mm/dump.c: { CONFIG_VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" },
For the Berlin and mm/dump code, we could very easily just have a #define VECTORS_BASE 0xffff0000 in a header file and drop the CONFIG_ prefix.
The MMU case does have to cater for CPUs wanting vectors at 0xffff0000 and at 0x00000000, and this is handled via the page tables - but this has nothing to do with CONFIG_VECTORS_BASE. CONFIG_VECTORS_BASE exists primarily for noMMU.
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