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Initializing TTBR0 to inner/outer WB

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While running tests on internal systems, we identified an issue in the
startup code for newlib on AArch32 systems with Multiprocessor
Extensions to the architecture.

The issue is we were configuring page table flags to be Inner
cacheable/Outer non-cacheable, while for at least architectures with
Multiprocessor Extension, we'd configure it to Inner/Outer write-back, no
write-allocate, and cacheable.

The attached patch fixes this, and no regression on arm-none-eabi
bare-metal tests.

Adopted suggestion given by Richard offline to avoid using jump.

libgloss/
	* arm/cpu-init/rdimon-aem.S: Set TTBR0 to inner/outer
	cacheable WB, and no allocate on WB for arch with multiprocessor
	extension.
This commit is contained in:
Jiong Wang 2016-03-24 14:32:04 +00:00 committed by Corinna Vinschen
parent 4799377456
commit 18b47e05d3
1 changed files with 10 additions and 1 deletions
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11
libgloss/arm/cpu-init/rdimon-aem.S
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@ -127,7 +127,16 @@ spin:
mcr 15, 0, r4, cr2, cr0, 2 @ Write TTBCR
adr r4, page_table_addr @ Load the base for vectors
ldr r4, [r4]
add r4, r4, #1 @ Page tables inner cacheable
mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
tst r0, #0x80000000 @ bis[31]
@ Set page table flags - there are two page table flag formats for the
@ architecture. For systems without multiprocessor extensions we use 0x1
@ which is Inner cacheable/Outer non-cacheable. For systems with
@ multiprocessor extensions we use 0x59 which is Inner/Outer write-back,
@ no write-allocate, and cacheable. See the ARMARM-v7AR for more details.
it ne
addne r4, r4, #0x58
add r4, r4, #1
mcr 15, 0, r4, cr2, cr0, 0 @ Write TTBR0