arm64: kpti-ng: simplify page table traversal logic
Simplify the KPTI G-to-nG asm helper code by: - pulling the 'table bit' test into the get/put macros so we can combine them and incorporate the entire loop; - moving the 'table bit' test after the update of bit #11 so we no longer need separate next_xxx and skip_xxx labels; - redefining the pmd/pud register aliases and the next_pmd/next_pud labels instead of branching to them if the number of configured page table levels is less than 3 or 4, respectively. No functional change intended, except for the fact that we now descend into a next level table after setting bit #11 on its descriptor but this should make no difference in practice. While at it, switch to .L prefixed local labels so they don't clutter up the symbol tables, kallsyms, etc, and clean up the indentation for legibility. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20220609174320.4035379-2-ardb@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ard Biesheuvel
Will Deacon
parent
a111daf0c5
commit
c7eff738cf
@ -202,19 +202,25 @@ SYM_FUNC_END(idmap_cpu_replace_ttbr1)
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#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
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.pushsection ".idmap.text", "awx"
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.macro __idmap_kpti_get_pgtable_ent, type
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dc cvac, cur_\()\type\()p // Ensure any existing dirty
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.macro kpti_mk_tbl_ng, type, num_entries
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add end_\type\()p, cur_\type\()p, #\num_entries * 8
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.Ldo_\type:
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dc cvac, cur_\type\()p // Ensure any existing dirty
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dmb sy // lines are written back before
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ldr \type, [cur_\()\type\()p] // loading the entry
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tbz \type, #0, skip_\()\type // Skip invalid and
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tbnz \type, #11, skip_\()\type // non-global entries
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.endm
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.macro __idmap_kpti_put_pgtable_ent_ng, type
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ldr \type, [cur_\type\()p] // loading the entry
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tbz \type, #0, .Lnext_\type // Skip invalid and
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tbnz \type, #11, .Lnext_\type // non-global entries
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orr \type, \type, #PTE_NG // Same bit for blocks and pages
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str \type, [cur_\()\type\()p] // Update the entry and ensure
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str \type, [cur_\type\()p] // Update the entry and ensure
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dmb sy // that it is visible to all
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dc civac, cur_\()\type\()p // CPUs.
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.ifnc \type, pte
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tbnz \type, #1, .Lderef_\type
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.endif
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.Lnext_\type:
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add cur_\type\()p, cur_\type\()p, #8
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cmp cur_\type\()p, end_\type\()p
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b.ne .Ldo_\type
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.endm
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/*
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@ -235,10 +241,8 @@ SYM_FUNC_START(idmap_kpti_install_ng_mappings)
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pgd .req x7
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cur_pudp .req x8
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end_pudp .req x9
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pud .req x10
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cur_pmdp .req x11
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end_pmdp .req x12
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pmd .req x13
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cur_ptep .req x14
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end_ptep .req x15
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pte .req x16
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@ -265,16 +269,8 @@ SYM_FUNC_START(idmap_kpti_install_ng_mappings)
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/* Everybody is enjoying the idmap, so we can rewrite swapper. */
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/* PGD */
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mov cur_pgdp, swapper_pa
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add end_pgdp, cur_pgdp, #(PTRS_PER_PGD * 8)
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do_pgd: __idmap_kpti_get_pgtable_ent pgd
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tbnz pgd, #1, walk_puds
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next_pgd:
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__idmap_kpti_put_pgtable_ent_ng pgd
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skip_pgd:
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add cur_pgdp, cur_pgdp, #8
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cmp cur_pgdp, end_pgdp
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b.ne do_pgd
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mov cur_pgdp, swapper_pa
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kpti_mk_tbl_ng pgd, PTRS_PER_PGD
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/* Publish the updated tables and nuke all the TLBs */
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dsb sy
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@ -291,59 +287,35 @@ skip_pgd:
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str wzr, [flag_ptr]
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ret
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.Lderef_pgd:
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/* PUD */
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walk_puds:
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.if CONFIG_PGTABLE_LEVELS > 3
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.if CONFIG_PGTABLE_LEVELS > 3
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pud .req x10
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pte_to_phys cur_pudp, pgd
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add end_pudp, cur_pudp, #(PTRS_PER_PUD * 8)
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do_pud: __idmap_kpti_get_pgtable_ent pud
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tbnz pud, #1, walk_pmds
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next_pud:
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__idmap_kpti_put_pgtable_ent_ng pud
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skip_pud:
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add cur_pudp, cur_pudp, 8
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cmp cur_pudp, end_pudp
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b.ne do_pud
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b next_pgd
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.else /* CONFIG_PGTABLE_LEVELS <= 3 */
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mov pud, pgd
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b walk_pmds
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next_pud:
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b next_pgd
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kpti_mk_tbl_ng pud, PTRS_PER_PUD
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b .Lnext_pgd
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.else /* CONFIG_PGTABLE_LEVELS <= 3 */
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pud .req pgd
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.set .Lnext_pud, .Lnext_pgd
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.endif
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.Lderef_pud:
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/* PMD */
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walk_pmds:
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.if CONFIG_PGTABLE_LEVELS > 2
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.if CONFIG_PGTABLE_LEVELS > 2
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pmd .req x13
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pte_to_phys cur_pmdp, pud
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add end_pmdp, cur_pmdp, #(PTRS_PER_PMD * 8)
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do_pmd: __idmap_kpti_get_pgtable_ent pmd
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tbnz pmd, #1, walk_ptes
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next_pmd:
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__idmap_kpti_put_pgtable_ent_ng pmd
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skip_pmd:
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add cur_pmdp, cur_pmdp, #8
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cmp cur_pmdp, end_pmdp
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b.ne do_pmd
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b next_pud
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.else /* CONFIG_PGTABLE_LEVELS <= 2 */
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mov pmd, pud
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b walk_ptes
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next_pmd:
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b next_pud
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kpti_mk_tbl_ng pmd, PTRS_PER_PMD
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b .Lnext_pud
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.else /* CONFIG_PGTABLE_LEVELS <= 2 */
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pmd .req pgd
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.set .Lnext_pmd, .Lnext_pgd
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.endif
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.Lderef_pmd:
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/* PTE */
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walk_ptes:
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pte_to_phys cur_ptep, pmd
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add end_ptep, cur_ptep, #(PTRS_PER_PTE * 8)
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do_pte: __idmap_kpti_get_pgtable_ent pte
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__idmap_kpti_put_pgtable_ent_ng pte
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skip_pte:
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add cur_ptep, cur_ptep, #8
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cmp cur_ptep, end_ptep
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b.ne do_pte
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b next_pmd
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kpti_mk_tbl_ng pte, PTRS_PER_PTE
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b .Lnext_pmd
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.unreq cpu
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.unreq num_cpus
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