[PATCH v5 02/14] ARM: Section based HYP idmap

[gleb@redhat.com (Gleb Natapov)]

On Tue, Jan 08, 2013 at 01:38:48PM -0500, Christoffer Dall wrote:
> Add a method (hyp_idmap_setup) to populate a hyp pgd with an
> identity mapping of the code contained in the .hyp.idmap.text
> section.
> 
> Offer a method to drop this identity mapping through
> hyp_idmap_teardown.
> 
> Make all the above depend on CONFIG_ARM_VIRT_EXT and CONFIG_ARM_LPAE.
> 
> Cc: Will Deacon <will.deacon@arm.com>
> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
> ---
>  arch/arm/include/asm/idmap.h                |    1 +
>  arch/arm/include/asm/pgtable-3level-hwdef.h |    1 +
>  arch/arm/kernel/vmlinux.lds.S               |    6 +++
>  arch/arm/mm/idmap.c                         |   54 ++++++++++++++++++++++-----
>  4 files changed, 50 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm/include/asm/idmap.h b/arch/arm/include/asm/idmap.h
> index bf863ed..1a66f907 100644
> --- a/arch/arm/include/asm/idmap.h
> +++ b/arch/arm/include/asm/idmap.h
> @@ -8,6 +8,7 @@
>  #define __idmap __section(.idmap.text) noinline notrace
>  
>  extern pgd_t *idmap_pgd;
> +extern pgd_t *hyp_pgd;
>  
>  void setup_mm_for_reboot(void);
>  
> diff --git a/arch/arm/include/asm/pgtable-3level-hwdef.h b/arch/arm/include/asm/pgtable-3level-hwdef.h
> index d795282..a2d404e 100644
> --- a/arch/arm/include/asm/pgtable-3level-hwdef.h
> +++ b/arch/arm/include/asm/pgtable-3level-hwdef.h
> @@ -44,6 +44,7 @@
>  #define PMD_SECT_XN		(_AT(pmdval_t, 1) << 54)
>  #define PMD_SECT_AP_WRITE	(_AT(pmdval_t, 0))
>  #define PMD_SECT_AP_READ	(_AT(pmdval_t, 0))
> +#define PMD_SECT_AP1		(_AT(pmdval_t, 1) << 6)
>  #define PMD_SECT_TEX(x)		(_AT(pmdval_t, 0))
>  
>  /*
> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
> index 11c1785..b571484 100644
> --- a/arch/arm/kernel/vmlinux.lds.S
> +++ b/arch/arm/kernel/vmlinux.lds.S
> @@ -19,7 +19,11 @@
>  	ALIGN_FUNCTION();						\
>  	VMLINUX_SYMBOL(__idmap_text_start) = .;				\
>  	*(.idmap.text)							\
> -	VMLINUX_SYMBOL(__idmap_text_end) = .;
> +	VMLINUX_SYMBOL(__idmap_text_end) = .;				\
> +	ALIGN_FUNCTION();						\
> +	VMLINUX_SYMBOL(__hyp_idmap_text_start) = .;			\
> +	*(.hyp.idmap.text)						\
> +	VMLINUX_SYMBOL(__hyp_idmap_text_end) = .;
>  
>  #ifdef CONFIG_HOTPLUG_CPU
>  #define ARM_CPU_DISCARD(x)
> diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
> index 99db769..d9213a5 100644
> --- a/arch/arm/mm/idmap.c
> +++ b/arch/arm/mm/idmap.c
> @@ -1,4 +1,6 @@
> +#include <linux/module.h>
>  #include <linux/kernel.h>
> +#include <linux/slab.h>
>  
>  #include <asm/cputype.h>
>  #include <asm/idmap.h>
> @@ -6,6 +8,7 @@
>  #include <asm/pgtable.h>
>  #include <asm/sections.h>
>  #include <asm/system_info.h>
> +#include <asm/virt.h>
>  
>  pgd_t *idmap_pgd;
>  
> @@ -59,11 +62,20 @@ static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
>  	} while (pud++, addr = next, addr != end);
>  }
>  
> -static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
> +static void identity_mapping_add(pgd_t *pgd, const char *text_start,
> +				 const char *text_end, unsigned long prot)
>  {
> -	unsigned long prot, next;
> +	unsigned long addr, end;
> +	unsigned long next;
> +
> +	addr = virt_to_phys(text_start);
> +	end = virt_to_phys(text_end);
How does this work with phys addresses greater than 32bit (with
LPAE)? This was the same before the patch too, but I am still
curious. Since __virt_to_phys() returns unsigned long kernel cannot be
put in high memory, right?


> +
> +	pr_info("Setting up static %sidentity map for 0x%llx - 0x%llx\n",
> +		prot ? "HYP " : "",
> +		(long long)addr, (long long)end);
> +	prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
>  
> -	prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
>  	if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
>  		prot |= PMD_BIT4;
>  
> @@ -74,28 +86,48 @@ static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long e
>  	} while (pgd++, addr = next, addr != end);
>  }
>  
> +#ifdef CONFIG_ARM_VIRT_EXT
> +pgd_t *hyp_pgd;
> +
> +extern char  __hyp_idmap_text_start[], __hyp_idmap_text_end[];
> +
> +static int __init init_static_idmap_hyp(void)
> +{
> +	hyp_pgd = kzalloc(PTRS_PER_PGD * sizeof(pgd_t), GFP_KERNEL);
> +	if (!hyp_pgd)
> +		return -ENOMEM;
> +
> +	identity_mapping_add(hyp_pgd, __hyp_idmap_text_start,
> +			     __hyp_idmap_text_end, PMD_SECT_AP1);
> +
> +	return 0;
> +}
> +#else
> +static int __init init_static_idmap_hyp(void)
> +{
> +	return 0;
> +}
> +#endif
> +
>  extern char  __idmap_text_start[], __idmap_text_end[];
>  
>  static int __init init_static_idmap(void)
>  {
> -	phys_addr_t idmap_start, idmap_end;
> +	int ret;
>  
>  	idmap_pgd = pgd_alloc(&init_mm);
>  	if (!idmap_pgd)
>  		return -ENOMEM;
>  
> -	/* Add an identity mapping for the physical address of the section. */
> -	idmap_start = virt_to_phys((void *)__idmap_text_start);
> -	idmap_end = virt_to_phys((void *)__idmap_text_end);
> +	identity_mapping_add(idmap_pgd, __idmap_text_start,
> +			     __idmap_text_end, 0);
>  
> -	pr_info("Setting up static identity map for 0x%llx - 0x%llx\n",
> -		(long long)idmap_start, (long long)idmap_end);
> -	identity_mapping_add(idmap_pgd, idmap_start, idmap_end);
> +	ret = init_static_idmap_hyp();
>  
>  	/* Flush L1 for the hardware to see this page table content */
>  	flush_cache_louis();
>  
> -	return 0;
> +	return ret;
>  }
>  early_initcall(init_static_idmap);
>  
> 
> --
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--
			Gleb.