[PATCH v2 01/10] ARM: p2v: fix handling of LPAE translation in BE mode

[Ard Biesheuvel]

On Tue, 22 Sep 2020 at 00:18, Russell King - ARM Linux admin
<linux at armlinux.org.uk> 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 at kernel.org>
>
> 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
> >
> >
>
> --
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