Messages in this thread Patch in this message | | | Date | Thu, 30 Nov 2017 18:29:56 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH v2 11/18] arm64: mm: Map entry trampoline into trampoline and kernel page tables |
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Hi Will,
On Thu, Nov 30, 2017 at 04:39:39PM +0000, Will Deacon wrote: > diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h > index 4052ec39e8db..8119b49be98d 100644 > --- a/arch/arm64/include/asm/fixmap.h > +++ b/arch/arm64/include/asm/fixmap.h > @@ -58,6 +58,10 @@ enum fixed_addresses { > FIX_APEI_GHES_NMI, > #endif /* CONFIG_ACPI_APEI_GHES */ > > +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 > + FIX_ENTRY_TRAMP_TEXT, > +#define TRAMP_VALIAS (__fix_to_virt(FIX_ENTRY_TRAMP_TEXT)) > +#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ > __end_of_permanent_fixed_addresses,
Defining TRAMP_VALIAS here is a little surprising, especially given we reuse the name in asm-offsets:
> + DEFINE(TRAMP_VALIAS, TRAMP_VALIAS);
Can't we have asm-offsets do:
DEFINE(TRAMP_VALIAS, __fix_to_virt(FIX_ENTRY_TRAMP_TEXT));
... and rely on the asm-offsets TRAMP_VALIAS definition everywhere? [...]
> +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 > +static int __init map_entry_trampoline(void) > +{ > + extern char __entry_tramp_text_start[]; > + > + pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; > + phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start); > + > + /* The trampoline is always mapped and can therefore be global */ > + pgprot_val(prot) &= ~PTE_NG; > + > + /* Map only the text into the trampoline page table */ > + memset((char *)tramp_pg_dir, 0, PGD_SIZE);
The (char *) cast can go; memset() takes a void pointer and we don't do similar casts for other memset instances.
> + __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE, > + prot, pgd_pgtable_alloc, 0); > + > + /* ...as well as the kernel page table */
This might be clearer as:
/* map the text in the kernel page table, too */ Otherwise, this looks good to me.
Thanks, Mark.
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