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Subject[PATCH v3 3/3] arm64/mm: migrate swapper_pg_dir and tramp_pg_dir
Date
Migrate swapper_pg_dir and tramp_pg_dir. And their virtual addresses
do not correlate with kernel's address.

Signed-off-by: Jun Yao <yaojun8558363@gmail.com>
---
arch/arm64/include/asm/pgtable.h | 1 +
arch/arm64/mm/mmu.c | 79 +++++++++++++++++++++-----------
2 files changed, 52 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 2bda899dcf22..b032d6c2e390 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -722,6 +722,7 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern pgd_t swapper_pg_end[];
extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
extern pgd_t tramp_pg_dir[PTRS_PER_PGD];
+extern pgd_t reserved_ttbr0[PTRS_PER_PGD];
extern volatile phys_addr_t __pa_swapper_pg_dir;
extern pgd_t *new_swapper_pg_dir;

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 94056e064c6f..ba0b55158971 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -63,6 +63,9 @@ volatile phys_addr_t __section(".mmuoff.data.read")
__pa_swapper_pg_dir;

pgd_t *new_swapper_pg_dir = swapper_pg_dir;
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+pgd_t *new_tramp_pg_dir;
+#endif

/*
* Empty_zero_page is a special page that is used for zero-initialized data
@@ -86,19 +89,14 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
}
EXPORT_SYMBOL(phys_mem_access_prot);

-static phys_addr_t __init early_pgtable_alloc(void)
+static void __init clear_page_phys(phys_addr_t phys)
{
- phys_addr_t phys;
- void *ptr;
-
- phys = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
-
/*
* The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE
* slot will be free, so we can (ab)use the FIX_PTE slot to initialise
* any level of table.
*/
- ptr = pte_set_fixmap(phys);
+ void *ptr = pte_set_fixmap(phys);

memset(ptr, 0, PAGE_SIZE);

@@ -107,6 +105,14 @@ static phys_addr_t __init early_pgtable_alloc(void)
* table walker
*/
pte_clear_fixmap();
+}
+
+static phys_addr_t __init early_pgtable_alloc(void)
+{
+ phys_addr_t phys;
+
+ phys = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+ clear_page_phys(phys);

return phys;
}
@@ -560,6 +566,10 @@ static int __init map_entry_trampoline(void)
__create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE,
prot, pgd_pgtable_alloc, 0);

+ memcpy(new_tramp_pg_dir, tramp_pg_dir, PGD_SIZE);
+ memblock_free(__pa_symbol(tramp_pg_dir),
+ __pa_symbol(swapper_pg_dir) - __pa_symbol(tramp_pg_dir));
+
/* Map both the text and data into the kernel page table */
__set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
@@ -637,10 +647,29 @@ static void __init map_kernel(pgd_t *pgdp)
*/
void __init paging_init(void)
{
- phys_addr_t pgd_phys = early_pgtable_alloc();
- pgd_t *pgdp = pgd_set_fixmap(pgd_phys);
+ phys_addr_t pgd_phys;
+ pgd_t *pgdp;
+ phys_addr_t mem_size;

- __pa_swapper_pg_dir = __pa_symbol(swapper_pg_dir);
+ mem_size = __pa_symbol(swapper_pg_dir) + PAGE_SIZE
+ - (__pa_symbol(idmap_pg_dir) + IDMAP_DIR_SIZE);
+
+ if (mem_size == PAGE_SIZE) {
+ pgd_phys = early_pgtable_alloc();
+ __pa_swapper_pg_dir = pgd_phys;
+ } else {
+ phys_addr_t p;
+
+ pgd_phys = memblock_alloc(mem_size, PAGE_SIZE);
+
+ for (p = pgd_phys; p < pgd_phys + mem_size; p += PAGE_SIZE)
+ clear_page_phys(p);
+
+ #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+ new_tramp_pg_dir = __va(pgd_phys);
+ #endif
+ __pa_swapper_pg_dir = pgd_phys + mem_size - PAGE_SIZE;
+ }

/*
* We need to clean '__pa_swapper_pg_dir' to the PoC, so that
@@ -649,31 +678,25 @@ void __init paging_init(void)
__flush_dcache_area((void *)&__pa_swapper_pg_dir,
sizeof(__pa_swapper_pg_dir));

+ new_swapper_pg_dir = __va(__pa_swapper_pg_dir);
+
+ pgdp = pgd_set_fixmap(__pa_swapper_pg_dir);
+
map_kernel(pgdp);
map_mem(pgdp);

- /*
- * We want to reuse the original swapper_pg_dir so we don't have to
- * communicate the new address to non-coherent secondaries in
- * secondary_entry, and so cpu_switch_mm can generate the address with
- * adrp+add rather than a load from some global variable.
- *
- * To do this we need to go via a temporary pgd.
- */
- cpu_replace_ttbr1(pgd_phys);
- memcpy(swapper_pg_dir, pgdp, PGD_SIZE);
cpu_replace_ttbr1(__pa_swapper_pg_dir);
+ init_mm.pgd = new_swapper_pg_dir;

pgd_clear_fixmap();
- memblock_free(pgd_phys, PAGE_SIZE);

- /*
- * We only reuse the PGD from the swapper_pg_dir, not the pud + pmd
- * allocated with it.
- */
- memblock_free(__pa_symbol(swapper_pg_dir) + PAGE_SIZE,
- __pa_symbol(swapper_pg_end) - __pa_symbol(swapper_pg_dir)
- - PAGE_SIZE);
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+ memblock_free(__pa_symbol(reserved_ttbr0), RESERVED_TTBR0_SIZE);
+#endif
+
+ memblock_free(__pa_symbol(swapper_pg_dir),
+ __pa_symbol(swapper_pg_end) - __pa_symbol(swapper_pg_dir));
+
}

/*
--
2.17.0
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