Re: [PATCH v4 09/10] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter

[Jason Yan]

On 2019/8/6 15:59, Christophe Leroy wrote:
> Le 05/08/2019 Ã 08:43, Jason Yan a ÃcritÂ:
> > One may want to disable kaslr when boot, so provide a cmdline parameter
> > 'nokaslr' to support this.
> >
> > Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
> > Cc: Diana Craciun <diana.craciun@xxxxxxx>
> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Cc: Christophe Leroy <christophe.leroy@xxxxxx>
> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Paul Mackerras <paulus@xxxxxxxxx>
> > Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Reviewed-by: Diana Craciun <diana.craciun@xxxxxxx>
> > Tested-by: Diana Craciun <diana.craciun@xxxxxxx>
>
> Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxx>
>
> Tiny comment below.
>
> > ---
> > Â arch/powerpc/kernel/kaslr_booke.c | 14 ++++++++++++++
> > Â 1 file changed, 14 insertions(+)
> >
> > diff --git a/arch/powerpc/kernel/kaslr_booke.c 
> > b/arch/powerpc/kernel/kaslr_booke.c
> > index 4b3f19a663fc..7c3cb41e7122 100644
> > --- a/arch/powerpc/kernel/kaslr_booke.c
> > +++ b/arch/powerpc/kernel/kaslr_booke.c
> > @@ -361,6 +361,18 @@ static unsigned long __init 
> > kaslr_choose_location(void *dt_ptr, phys_addr_t size
> > ÂÂÂÂÂ return kaslr_offset;
> > Â }
> > +static inline __init bool kaslr_disabled(void)
> > +{
> > +ÂÂÂ char *str;
> > +
> > +ÂÂÂ str = strstr(boot_command_line, "nokaslr");
> > +ÂÂÂ if ((str == boot_command_line) ||
> > +ÂÂÂÂÂÂÂ (str > boot_command_line && *(str - 1) == ' '))
> > +ÂÂÂÂÂÂÂ return true;
>
> I don't think additional () are needed for the left part 'str == 
> boot_command_line'

Agree.

> > +
> > +ÂÂÂ return false;
> > +}
> > +
> > Â /*
> > ÂÂ * To see if we need to relocate the kernel to a random offset
> > ÂÂ * void *dt_ptr - address of the device tree
> > @@ -376,6 +388,8 @@ notrace void __init kaslr_early_init(void *dt_ptr, 
> > phys_addr_t size)
> > ÂÂÂÂÂ kernel_sz = (unsigned long)_end - KERNELBASE;
> > ÂÂÂÂÂ kaslr_get_cmdline(dt_ptr);
> > +ÂÂÂ if (kaslr_disabled())
> > +ÂÂÂÂÂÂÂ return;
> > ÂÂÂÂÂ offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
>
> .