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-rw-r--r--arch/arm64/include/asm/kernel-pgtable.h16
-rw-r--r--arch/arm64/kernel/head.S31
-rw-r--r--arch/arm64/kernel/vmlinux.lds.S7
-rw-r--r--arch/arm64/mm/mmu.c35
-rw-r--r--arch/arm64/mm/proc.S8
5 files changed, 76 insertions, 21 deletions
diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
index 96dc0f7da258..5395e5a04f35 100644
--- a/arch/arm64/include/asm/kernel-pgtable.h
+++ b/arch/arm64/include/asm/kernel-pgtable.h
@@ -35,10 +35,8 @@
*/
#if ARM64_KERNEL_USES_PMD_MAPS
#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
-#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT) - 1)
#else
#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
-#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
#endif
@@ -87,7 +85,13 @@
+ EARLY_PUDS((vstart), (vend)) /* each PUD needs a next level page table */ \
+ EARLY_PMDS((vstart), (vend))) /* each PMD needs a next level page table */
#define INIT_DIR_SIZE (PAGE_SIZE * EARLY_PAGES(KIMAGE_VADDR, _end))
-#define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE)
+
+/* the initial ID map may need two extra pages if it needs to be extended */
+#if VA_BITS < 48
+#define INIT_IDMAP_DIR_SIZE (INIT_DIR_SIZE + (2 * PAGE_SIZE))
+#else
+#define INIT_IDMAP_DIR_SIZE INIT_DIR_SIZE
+#endif
/* Initial memory map size */
#if ARM64_KERNEL_USES_PMD_MAPS
@@ -107,9 +111,11 @@
#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
#if ARM64_KERNEL_USES_PMD_MAPS
-#define SWAPPER_MM_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
+#define SWAPPER_RW_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS)
+#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PMD_SECT_RDONLY)
#else
-#define SWAPPER_MM_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
+#define SWAPPER_RW_MMUFLAGS (PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
+#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
#endif
/*
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 7397555f8437..93734c91a29a 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -87,6 +87,7 @@
* x28 clear_page_tables() callee preserved temp register
* x19/x20 __primary_switch() callee preserved temp registers
* x24 __primary_switch() .. relocate_kernel() current RELR displacement
+ * x28 create_idmap() callee preserved temp register
*/
SYM_CODE_START(primary_entry)
bl preserve_boot_args
@@ -298,9 +299,7 @@ SYM_FUNC_START_LOCAL(remap_region)
SYM_FUNC_END(remap_region)
SYM_FUNC_START_LOCAL(create_idmap)
- adrp x0, idmap_pg_dir
- adrp x3, __idmap_text_start // __pa(__idmap_text_start)
-
+ mov x28, lr
/*
* The ID map carries a 1:1 mapping of the physical address range
* covered by the loaded image, which could be anywhere in DRAM. This
@@ -347,11 +346,22 @@ SYM_FUNC_START_LOCAL(create_idmap)
* translation level, but the top-level table has more entries.
*/
#endif
- adr_l x6, __idmap_text_end // __pa(__idmap_text_end)
- mov x7, SWAPPER_MM_MMUFLAGS
+ adrp x0, init_idmap_pg_dir
+ adrp x3, _text
+ adrp x6, _end
+ mov x7, SWAPPER_RX_MMUFLAGS
map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT
+ /* Remap the kernel page tables r/w in the ID map */
+ adrp x1, _text
+ adrp x2, init_pg_dir
+ adrp x3, init_pg_end
+ bic x4, x2, #SWAPPER_BLOCK_SIZE - 1
+ mov x5, SWAPPER_RW_MMUFLAGS
+ mov x6, #SWAPPER_BLOCK_SHIFT
+ bl remap_region
+
/*
* Since the page tables have been populated with non-cacheable
* accesses (MMU disabled), invalidate those tables again to
@@ -359,9 +369,10 @@ SYM_FUNC_START_LOCAL(create_idmap)
*/
dmb sy
- adrp x0, idmap_pg_dir
- adrp x1, idmap_pg_end
- b dcache_inval_poc // tail call
+ adrp x0, init_idmap_pg_dir
+ adrp x1, init_idmap_pg_end
+ bl dcache_inval_poc
+ ret x28
SYM_FUNC_END(create_idmap)
SYM_FUNC_START_LOCAL(create_kernel_mapping)
@@ -372,7 +383,7 @@ SYM_FUNC_START_LOCAL(create_kernel_mapping)
adrp x3, _text // runtime __pa(_text)
sub x6, x6, x3 // _end - _text
add x6, x6, x5 // runtime __va(_end)
- mov x7, SWAPPER_MM_MMUFLAGS
+ mov x7, SWAPPER_RW_MMUFLAGS
map_memory x0, x1, x5, x6, x7, x3, (VA_BITS - PGDIR_SHIFT), x10, x11, x12, x13, x14
@@ -853,7 +864,7 @@ SYM_FUNC_START_LOCAL(__primary_switch)
#endif
adrp x1, init_pg_dir
- adrp x2, idmap_pg_dir
+ adrp x2, init_idmap_pg_dir
bl __enable_mmu
#ifdef CONFIG_RELOCATABLE
#ifdef CONFIG_RELR
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 2d4a8f995175..533673793bc0 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -198,8 +198,7 @@ SECTIONS
}
idmap_pg_dir = .;
- . += IDMAP_DIR_SIZE;
- idmap_pg_end = .;
+ . += PAGE_SIZE;
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
tramp_pg_dir = .;
@@ -235,6 +234,10 @@ SECTIONS
__inittext_end = .;
__initdata_begin = .;
+ init_idmap_pg_dir = .;
+ . += INIT_IDMAP_DIR_SIZE;
+ init_idmap_pg_end = .;
+
.init.data : {
INIT_DATA
INIT_SETUP(16)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 8cbc87dcaad3..fd558cfcf3ad 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -766,9 +766,40 @@ static void __init map_kernel(pgd_t *pgdp)
kasan_copy_shadow(pgdp);
}
+static void __init create_idmap(void)
+{
+ u64 start = __pa_symbol(__idmap_text_start);
+ u64 size = __pa_symbol(__idmap_text_end) - start;
+ pgd_t *pgd = idmap_pg_dir;
+ u64 pgd_phys;
+
+ /* check if we need an additional level of translation */
+ if (VA_BITS < 48 && idmap_t0sz < (64 - VA_BITS_MIN)) {
+ pgd_phys = early_pgtable_alloc(PAGE_SHIFT);
+ set_pgd(&idmap_pg_dir[start >> VA_BITS],
+ __pgd(pgd_phys | P4D_TYPE_TABLE));
+ pgd = __va(pgd_phys);
+ }
+ __create_pgd_mapping(pgd, start, start, size, PAGE_KERNEL_ROX,
+ early_pgtable_alloc, 0);
+
+ if (IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) {
+ extern u32 __idmap_kpti_flag;
+ u64 pa = __pa_symbol(&__idmap_kpti_flag);
+
+ /*
+ * The KPTI G-to-nG conversion code needs a read-write mapping
+ * of its synchronization flag in the ID map.
+ */
+ __create_pgd_mapping(pgd, pa, pa, sizeof(u32), PAGE_KERNEL,
+ early_pgtable_alloc, 0);
+ }
+}
+
void __init paging_init(void)
{
pgd_t *pgdp = pgd_set_fixmap(__pa_symbol(swapper_pg_dir));
+ extern pgd_t init_idmap_pg_dir[];
idmap_t0sz = 63UL - __fls(__pa_symbol(_end) | GENMASK(VA_BITS_MIN - 1, 0));
@@ -777,13 +808,15 @@ void __init paging_init(void)
pgd_clear_fixmap();
- cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir);
+ cpu_replace_ttbr1(lm_alias(swapper_pg_dir), init_idmap_pg_dir);
init_mm.pgd = swapper_pg_dir;
memblock_phys_free(__pa_symbol(init_pg_dir),
__pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir));
memblock_allow_resize();
+
+ create_idmap();
}
/*
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index e802badf9ac0..605c6640f94b 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -222,8 +222,10 @@ SYM_FUNC_END(idmap_cpu_replace_ttbr1)
*
* Called exactly once from stop_machine context by each CPU found during boot.
*/
-__idmap_kpti_flag:
- .long 1
+ .pushsection ".data", "aw", %progbits
+SYM_DATA(__idmap_kpti_flag, .long 1)
+ .popsection
+
SYM_FUNC_START(idmap_kpti_install_ng_mappings)
cpu .req w0
num_cpus .req w1
@@ -245,7 +247,7 @@ SYM_FUNC_START(idmap_kpti_install_ng_mappings)
mrs swapper_ttb, ttbr1_el1
restore_ttbr1 swapper_ttb
- adr flag_ptr, __idmap_kpti_flag
+ adr_l flag_ptr, __idmap_kpti_flag
cbnz cpu, __idmap_kpti_secondary
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.