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arm64: mm: Introduce vabits_actual 

In order to support 52-bit kernel addresses detectable at boot time, one
needs to know the actual VA_BITS detected. A new variable vabits_actual
is introduced in this commit and employed for the KVM hypervisor layout,
KASAN, fault handling and phys-to/from-virt translation where there
would normally be compile time constants.

In order to maintain performance in phys_to_virt, another variable
physvirt_offset is introduced.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
alistair/sunxi64-5.4-dsi
Steve Capper 2019-08-07 16:55:18 +01:00 committed by Will Deacon
parent 90ec95cda9
commit 5383cc6efe
8 changed files with 31 additions and 17 deletions
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2
arch/arm64/include/asm/kasan.h
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@ -31,7 +31,7 @@
* (1ULL << (64 - KASAN_SHADOW_SCALE_SHIFT))
*/
#define _KASAN_SHADOW_START(va) (KASAN_SHADOW_END - (1UL << ((va) - KASAN_SHADOW_SCALE_SHIFT)))
#define KASAN_SHADOW_START _KASAN_SHADOW_START(VA_BITS)
#define KASAN_SHADOW_START _KASAN_SHADOW_START(vabits_actual)
void kasan_init(void);
void kasan_copy_shadow(pgd_t *pgdir);

11
arch/arm64/include/asm/memory.h
View File

@ -37,8 +37,6 @@
* VA_START - the first kernel virtual address.
*/
#define VA_BITS (CONFIG_ARM64_VA_BITS)
#define VA_START (UL(0xffffffffffffffff) - \
(UL(1) << (VA_BITS - 1)) + 1)
#define PAGE_OFFSET (UL(0xffffffffffffffff) - \
(UL(1) << VA_BITS) + 1)
#define KIMAGE_VADDR (MODULES_END)
@ -166,10 +164,13 @@
#endif
#ifndef __ASSEMBLY__
extern u64 vabits_actual;
#define VA_START (_VA_START(vabits_actual))
#include <linux/bitops.h>
#include <linux/mmdebug.h>
extern s64 physvirt_offset;
extern s64 memstart_addr;
/* PHYS_OFFSET - the physical address of the start of memory. */
#define PHYS_OFFSET ({ VM_BUG_ON(memstart_addr & 1); memstart_addr; })
@ -240,9 +241,9 @@ static inline const void *__tag_set(const void *addr, u8 tag)
* space. Testing the top bit for the start of the region is a
* sufficient check.
*/
#define __is_lm_address(addr) (!((addr) & BIT(VA_BITS - 1)))
#define __is_lm_address(addr) (!((addr) & BIT(vabits_actual - 1)))
#define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
#define __lm_to_phys(addr) (((addr) + physvirt_offset))
#define __kimg_to_phys(addr) ((addr) - kimage_voffset)
#define __virt_to_phys_nodebug(x) ({ \
@ -261,7 +262,7 @@ extern phys_addr_t __phys_addr_symbol(unsigned long x);
#define __phys_addr_symbol(x) __pa_symbol_nodebug(x)
#endif
#define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET)
#define __phys_to_virt(x) ((unsigned long)((x) - physvirt_offset))
#define __phys_to_kimg(x) ((unsigned long)((x) + kimage_voffset))
/*

2
arch/arm64/include/asm/mmu_context.h
View File

@ -95,7 +95,7 @@ static inline void __cpu_set_tcr_t0sz(unsigned long t0sz)
isb();
}
#define cpu_set_default_tcr_t0sz() __cpu_set_tcr_t0sz(TCR_T0SZ(VA_BITS))
#define cpu_set_default_tcr_t0sz() __cpu_set_tcr_t0sz(TCR_T0SZ(vabits_actual))
#define cpu_set_idmap_tcr_t0sz() __cpu_set_tcr_t0sz(idmap_t0sz)
/*

5
arch/arm64/kernel/head.S
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@ -321,6 +321,11 @@ __create_page_tables:
dmb sy
dc ivac, x6 // Invalidate potentially stale cache line
adr_l x6, vabits_actual
str x5, [x6]
dmb sy
dc ivac, x6 // Invalidate potentially stale cache line
/*
* VA_BITS may be too small to allow for an ID mapping to be created
* that covers system RAM if that is located sufficiently high in the

14
arch/arm64/kvm/va_layout.c
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@ -29,25 +29,25 @@ static void compute_layout(void)
int kva_msb;
/* Where is my RAM region? */
hyp_va_msb = idmap_addr & BIT(VA_BITS - 1);
hyp_va_msb ^= BIT(VA_BITS - 1);
hyp_va_msb = idmap_addr & BIT(vabits_actual - 1);
hyp_va_msb ^= BIT(vabits_actual - 1);
kva_msb = fls64((u64)phys_to_virt(memblock_start_of_DRAM()) ^
(u64)(high_memory - 1));
if (kva_msb == (VA_BITS - 1)) {
if (kva_msb == (vabits_actual - 1)) {
/*
* No space in the address, let's compute the mask so
* that it covers (VA_BITS - 1) bits, and the region
* that it covers (vabits_actual - 1) bits, and the region
* bit. The tag stays set to zero.
*/
va_mask = BIT(VA_BITS - 1) - 1;
va_mask = BIT(vabits_actual - 1) - 1;
va_mask |= hyp_va_msb;
} else {
/*
* We do have some free bits to insert a random tag.
* Hyp VAs are now created from kernel linear map VAs
* using the following formula (with V == VA_BITS):
* using the following formula (with V == vabits_actual):
*
* 63 ... V | V-1 | V-2 .. tag_lsb | tag_lsb - 1 .. 0
* ---------------------------------------------------------
@ -55,7 +55,7 @@ static void compute_layout(void)
*/
tag_lsb = kva_msb;
va_mask = GENMASK_ULL(tag_lsb - 1, 0);
tag_val = get_random_long() & GENMASK_ULL(VA_BITS - 2, tag_lsb);
tag_val = get_random_long() & GENMASK_ULL(vabits_actual - 2, tag_lsb);
tag_val |= hyp_va_msb;
tag_val >>= tag_lsb;
}

4
arch/arm64/mm/fault.c
View File

@ -138,9 +138,9 @@ static void show_pte(unsigned long addr)
return;
}
pr_alert("%s pgtable: %luk pages, %u-bit VAs, pgdp=%016lx\n",
pr_alert("%s pgtable: %luk pages, %llu-bit VAs, pgdp=%016lx\n",
mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K,
mm == &init_mm ? VA_BITS : (int)vabits_user,
mm == &init_mm ? vabits_actual : (int)vabits_user,
(unsigned long)virt_to_phys(mm->pgd));
pgdp = pgd_offset(mm, addr);
pgd = READ_ONCE(*pgdp);

7
arch/arm64/mm/init.c
View File

@ -50,6 +50,9 @@
s64 memstart_addr __ro_after_init = -1;
EXPORT_SYMBOL(memstart_addr);
s64 physvirt_offset __ro_after_init;
EXPORT_SYMBOL(physvirt_offset);
phys_addr_t arm64_dma_phys_limit __ro_after_init;
#ifdef CONFIG_KEXEC_CORE
@ -301,7 +304,7 @@ static void __init fdt_enforce_memory_region(void)
void __init arm64_memblock_init(void)
{
const s64 linear_region_size = BIT(VA_BITS - 1);
const s64 linear_region_size = BIT(vabits_actual - 1);
/* Handle linux,usable-memory-range property */
fdt_enforce_memory_region();
@ -315,6 +318,8 @@ void __init arm64_memblock_init(void)
memstart_addr = round_down(memblock_start_of_DRAM(),
ARM64_MEMSTART_ALIGN);
physvirt_offset = PHYS_OFFSET - PAGE_OFFSET;
/*
* Remove the memory that we will not be able to cover with the
* linear mapping. Take care not to clip the kernel which may be

3
arch/arm64/mm/mmu.c
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@ -43,6 +43,9 @@ u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
u64 vabits_user __ro_after_init;
EXPORT_SYMBOL(vabits_user);
u64 __section(".mmuoff.data.write") vabits_actual;
EXPORT_SYMBOL(vabits_actual);
u64 kimage_voffset __ro_after_init;
EXPORT_SYMBOL(kimage_voffset);