On Tue, 22 Sep 2020 at 00:18, Russell King - ARM Linux admin
<linux@xxxxxxxxxxxxxxx> wrote:
>
> On Mon, Sep 21, 2020 at 05:41:08PM +0200, Ard Biesheuvel wrote:
> > When running in BE mode on LPAE hardware with a PA-to-VA translation
> > that exceeds 4 GB, we patch bits 39:32 of the offset into the wrong
> > byte of the opcode. So fix that, by rotating the offset in r0 to the
> > right by 8 bits, which will put the 8-bit immediate in bits 31:24.
> >
> > Note that this will also move bit #22 in its correct place when
> > applying the rotation to the constant #0x400000.
> >
> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
>
> Should this have a fixes tag?
>
Indeed. I will add
Fixes: d9a790df8e984 ("ARM: 7883/1: fix mov to mvn conversion in case
of 64 bit phys_addr_t and BE")
before I send the PR.
> > ---
> > arch/arm/kernel/head.S | 6 +-----
> > 1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> > index f8904227e7fd..98c1e68bdfcb 100644
> > --- a/arch/arm/kernel/head.S
> > +++ b/arch/arm/kernel/head.S
> > @@ -671,12 +671,8 @@ ARM_BE8(rev16 ip, ip)
> > ldrcc r7, [r4], #4 @ use branch for delay slot
> > bcc 1b
> > bx lr
> > -#else
> > -#ifdef CONFIG_CPU_ENDIAN_BE8
> > - moveq r0, #0x00004000 @ set bit 22, mov to mvn instruction
> > #else
> > moveq r0, #0x400000 @ set bit 22, mov to mvn instruction
> > -#endif
> > b 2f
> > 1: ldr ip, [r7, r3]
> > #ifdef CONFIG_CPU_ENDIAN_BE8
> > @@ -685,7 +681,7 @@ ARM_BE8(rev16 ip, ip)
> > tst ip, #0x000f0000 @ check the rotation field
> > orrne ip, ip, r6, lsl #24 @ mask in offset bits 31-24
> > biceq ip, ip, #0x00004000 @ clear bit 22
> > - orreq ip, ip, r0 @ mask in offset bits 7-0
> > + orreq ip, ip, r0, ror #8 @ mask in offset bits 7-0
> > #else
> > bic ip, ip, #0x000000ff
> > tst ip, #0xf00 @ check the rotation field
> > --
> > 2.17.1
> >
> >
>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
