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Message-ID: <YdV3RzQcGb2xFPhS@FVFF77S0Q05N>
Date: Wed, 5 Jan 2022 10:47:35 +0000
From: Mark Rutland <mark.rutland@....com>
To: AliOS system security <alios_sys_security@...ux.alibaba.com>
Cc: Anshuman Khandual <anshuman.khandual@....com>,
catalin.marinas@....com, will@...nel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: fix build error when use rodata_enabled
On Wed, Jan 05, 2022 at 02:51:05PM +0530, Anshuman Khandual wrote:
> Hello,
>
> On 1/5/22 8:37 AM, AliOS system security wrote:
> > rodata_enabled should be used when CONFIG_STRICT_KERNEL_RWX
> > or CONFIG_STRICT_MODULE_RWX is selected
Further to Anshuman's comments here, for a build issue, please include the
specific build error in the commit log, and describe the configuration where
this manifests.
For the reasons Anshuman gives below I do not see how this can be a problem in
mainline.
Thanks,
Mark.
> Both these configs get selected invariably with CONFIG_ARM64 in the
> platform config file (arch/arm64/Kconfig). I guess there can not be
> any such situation, where both configs will be missing/not selected
> given ARCH_OPTIONAL_KERNEL_RWX[or _DEFAULT] is not enabled on arm64.
>
> config ARM64
> def_bool y
> select ACPI_CCA_REQUIRED if ACPI
> .....
> select ARCH_HAS_STRICT_KERNEL_RWX
> select ARCH_HAS_STRICT_MODULE_RWX
> .....
>
> Hence for all practical purpose, rodata_enabled could be considered
> always available. I am sure there other similar situations as well,
> where code elements are not wrapped around if the config option is
> always present.
>
> >
> > Signed-off-by: AliOS system security <alios_sys_security@...ux.alibaba.com>
>
> Also please refer Documentation/process/submitting-patches.rst for
> the rules regarding names, that can be used for a commit sign off.
>
> ------------------------------------------------------------------------
> then you just add a line saying::
>
> Signed-off-by: Random J Developer <random@...eloper.example.org>
>
> using your real name (sorry, no pseudonyms or anonymous contributions.)
> ------------------------------------------------------------------------
>
> - Anshuman
>
> > ---
> > arch/arm64/mm/mmu.c | 14 ++++++++++++--
> > 1 file changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index acfae9b..47f8754 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -596,6 +596,7 @@ static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end,
> > vm_area_add_early(vma);
> > }
> >
> > +#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
> > static int __init parse_rodata(char *arg)
> > {
> > int ret = strtobool(arg, &rodata_enabled);
> > @@ -613,11 +614,16 @@ static int __init parse_rodata(char *arg)
> > return 0;
> > }
> > early_param("rodata", parse_rodata);
> > +#endif
> >
> > #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
> > static int __init map_entry_trampoline(void)
> > {
> > - pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
> > + pgprot_t prot = PAGE_KERNEL_EXEC;
> > +#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
> > + if (rodata_enabled)
> > + prot = PAGE_KERNEL_ROX;
> > +#endif
> > phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start);
> >
> > /* The trampoline is always mapped and can therefore be global */
> > @@ -672,7 +678,11 @@ static void __init map_kernel(pgd_t *pgdp)
> > * mapping to install SW breakpoints. Allow this (only) when
> > * explicitly requested with rodata=off.
> > */
> > - pgprot_t text_prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
> > + pgprot_t text_prot = PAGE_KERNEL_EXEC;
> > +#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
> > + if (rodata_enabled)
> > + text_prot = PAGE_KERNEL_ROX;
> > +#endif
> >
> > /*
> > * If we have a CPU that supports BTI and a kernel built for
> >
>
> _______________________________________________
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