arm64: add FIXADDR_TOT_{START,SIZE}

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>

diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h
index 71ed5fd..508238f 100644 (file)
--- a/arch/arm64/include/asm/fixmap.h
+++ b/arch/arm64/include/asm/fixmap.h
@@ -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)
 

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 9813f2a..4495425 100644 (file)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -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);

diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
index 9bc4066..e305b65 100644 (file)
--- a/arch/arm64/mm/ptdump.c
+++ b/arch/arm64/mm/ptdump.c
@@ -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" },