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arm64: add FIXADDR_TOT_{START,SIZE}

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Currently arm64's FIXADDR_{START,SIZE} definitions only cover the
runtime fixmap slots (and not the boot-time fixmap slots), but the code
for creating the fixmap assumes that these definitions cover the entire
fixmap range. This means that the ptdump boundaries are reported in a
misleading way, missing the VA region of the runtime slots. In theory
this could also cause the fixmap creation to go wrong if the boot-time
fixmap slots end up spilling into a separate PMD entry, though luckily
this is not currently the case in any configuration.

While it seems like we could extend FIXADDR_{START,SIZE} to cover the
entire fixmap area, core code relies upon these *only* covering the
runtime slots. For example, fix_to_virt() and virt_to_fix() try to
reject manipulation of the boot-time slots based upon
FIXADDR_{START,SIZE}, while __fix_to_virt() and __virt_to_fix() can
handle any fixmap slot.

This patch follows the lead of x86 in commit:

  55f49fcb879fbeeb ("x86/mm: Fix overlap of i386 CPU_ENTRY_AREA with FIX_BTMAP")

... and add new FIXADDR_TOT_{START,SIZE} definitions which cover the
entire fixmap area, using these for the fixmap creation and ptdump code.

As the boot-time fixmap slots are now rejected by fix_to_virt(),
the early_fixmap_init() code is changed to consistently use
__fix_to_virt(), as it already does in a few cases.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/r/20230406152759.4164229-2-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mark Rutland 2023-04-06 16:27:57 +01:00 committed by Will Deacon
parent 7bd6680b47
commit 32f5b6995f
3 changed files with 18 additions and 16 deletions
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6
arch/arm64/include/asm/fixmap.h
View File

@ -95,8 +95,10 @@ enum fixed_addresses {
__end_of_fixed_addresses
};
#define FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
#define FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
#define FIXADDR_TOT_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_TOT_START (FIXADDR_TOP - FIXADDR_TOT_SIZE)
#define FIXMAP_PAGE_IO __pgprot(PROT_DEVICE_nGnRE)

26
arch/arm64/mm/mmu.c
View File

@ -795,14 +795,14 @@ static void __init map_kernel(pgd_t *pgdp)
&vmlinux_initdata, 0, VM_NO_GUARD);
map_kernel_segment(pgdp, _data, _end, PAGE_KERNEL, &vmlinux_data, 0, 0);
if (!READ_ONCE(pgd_val(*pgd_offset_pgd(pgdp, FIXADDR_START)))) {
if (!READ_ONCE(pgd_val(*pgd_offset_pgd(pgdp, FIXADDR_TOT_START)))) {
/*
* The fixmap falls in a separate pgd to the kernel, and doesn't
* live in the carveout for the swapper_pg_dir. We can simply
* re-use the existing dir for the fixmap.
*/
set_pgd(pgd_offset_pgd(pgdp, FIXADDR_START),
READ_ONCE(*pgd_offset_k(FIXADDR_START)));
set_pgd(pgd_offset_pgd(pgdp, FIXADDR_TOT_START),
READ_ONCE(*pgd_offset_k(FIXADDR_TOT_START)));
} else if (CONFIG_PGTABLE_LEVELS > 3) {
pgd_t *bm_pgdp;
p4d_t *bm_p4dp;
@ -814,9 +814,9 @@ static void __init map_kernel(pgd_t *pgdp)
* entry instead.
*/
BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
bm_pgdp = pgd_offset_pgd(pgdp, FIXADDR_START);
bm_p4dp = p4d_offset(bm_pgdp, FIXADDR_START);
bm_pudp = pud_set_fixmap_offset(bm_p4dp, FIXADDR_START);
bm_pgdp = pgd_offset_pgd(pgdp, FIXADDR_TOT_START);
bm_p4dp = p4d_offset(bm_pgdp, FIXADDR_TOT_START);
bm_pudp = pud_set_fixmap_offset(bm_p4dp, FIXADDR_TOT_START);
pud_populate(&init_mm, bm_pudp, lm_alias(bm_pmd));
pud_clear_fixmap();
} else {
@ -1275,7 +1275,7 @@ void __init early_fixmap_init(void)
p4d_t *p4dp, p4d;
pud_t *pudp;
pmd_t *pmdp;
unsigned long addr = FIXADDR_START;
unsigned long addr = FIXADDR_TOT_START;
pgdp = pgd_offset_k(addr);
p4dp = p4d_offset(pgdp, addr);
@ -1306,16 +1306,16 @@ void __init early_fixmap_init(void)
BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
!= (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));
if ((pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)))
|| pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_END))) {
if ((pmdp != fixmap_pmd(__fix_to_virt(FIX_BTMAP_BEGIN)))
|| pmdp != fixmap_pmd(__fix_to_virt(FIX_BTMAP_END))) {
WARN_ON(1);
pr_warn("pmdp %p != %p, %p\n",
pmdp, fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)),
fixmap_pmd(fix_to_virt(FIX_BTMAP_END)));
pmdp, fixmap_pmd(__fix_to_virt(FIX_BTMAP_BEGIN)),
fixmap_pmd(__fix_to_virt(FIX_BTMAP_END)));
pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
fix_to_virt(FIX_BTMAP_BEGIN));
__fix_to_virt(FIX_BTMAP_BEGIN));
pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n",
fix_to_virt(FIX_BTMAP_END));
__fix_to_virt(FIX_BTMAP_END));
pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END);
pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN);

2
arch/arm64/mm/ptdump.c
View File

@ -45,7 +45,7 @@ static struct addr_marker address_markers[] = {
{ MODULES_END, "Modules end" },
{ VMALLOC_START, "vmalloc() area" },
{ VMALLOC_END, "vmalloc() end" },
{ FIXADDR_START, "Fixmap start" },
{ FIXADDR_TOT_START, "Fixmap start" },
{ FIXADDR_TOP, "Fixmap end" },
{ PCI_IO_START, "PCI I/O start" },
{ PCI_IO_END, "PCI I/O end" },