| Message ID | 1473663420-18629-1-git-send-email-sramana@codeaurora.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | Andy Gross |
| Headers | show |
On Mon, Sep 12, 2016 at 12:27:00PM +0530, Srinivas Ramana wrote: > If the bootloader uses the long descriptor format and jumps to > kernel decompressor code, TTBCR may not be in a right state. > Before enabling the MMU, it is required to clear the TTBCR.PD0 > field to use TTBR0 for translation table walks. > > The 'commit dbece45894d3a ("ARM: 7501/1: decompressor: > reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but There's no need to single-quote the commit part of this sentence. > doesn't consider all the bits for the size of TTBCR.N. > > Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to > indicate the use of TTBR0 and the correct base address width. > Adding a properly formatted Fixes: line here would be a bonus if we need to backport it to stable trees. > Signed-off-by: Srinivas Ramana <sramana@codeaurora.org> > --- > arch/arm/boot/compressed/head.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S > index af11c2f8f3b7..fc6d541549a2 100644 > --- a/arch/arm/boot/compressed/head.S > +++ b/arch/arm/boot/compressed/head.S > @@ -779,7 +779,7 @@ __armv7_mmu_cache_on: > orrne r0, r0, #1 @ MMU enabled > movne r1, #0xfffffffd @ domain 0 = client > bic r6, r6, #1 << 31 @ 32-bit translation system > - bic r6, r6, #3 << 0 @ use only ttbr0 > + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0 Provided this is correct (I've not checked, I'd like an ack from one of the ARM people, and I'd prefer to see a tested-by as well), and the above points are addressed, it can be dropped into the patch system. Thanks.
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index af11c2f8f3b7..fc6d541549a2 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -779,7 +779,7 @@ __armv7_mmu_cache_on: orrne r0, r0, #1 @ MMU enabled movne r1, #0xfffffffd @ domain 0 = client bic r6, r6, #1 << 31 @ 32-bit translation system - bic r6, r6, #3 << 0 @ use only ttbr0 + bic r6, r6, #(7 << 0) | (1 << 4) @ use only ttbr0 mcrne p15, 0, r3, c2, c0, 0 @ load page table pointer mcrne p15, 0, r1, c3, c0, 0 @ load domain access control mcrne p15, 0, r6, c2, c0, 2 @ load ttb control
If the bootloader uses the long descriptor format and jumps to kernel decompressor code, TTBCR may not be in a right state. Before enabling the MMU, it is required to clear the TTBCR.PD0 field to use TTBR0 for translation table walks. The 'commit dbece45894d3a ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")' does the reset of TTBCR.N, but doesn't consider all the bits for the size of TTBCR.N. Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to indicate the use of TTBR0 and the correct base address width. Signed-off-by: Srinivas Ramana <sramana@codeaurora.org> --- arch/arm/boot/compressed/head.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)