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Thu, 9 Jun 2022 14:50:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4FDE6C341C4; Thu, 9 Jun 2022 14:50:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654786218; bh=PGV5z/hwWD/WY6LTPdcVIyvFPWs5KrYYPYO3fmfh2NY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z+OnM1WuIyzGujKD3l21QpyiWBdIA9cJ4/Lo0J53TJCoihEqdt0RBcC0ZuIWm+J// cNYRKYfltmbMeE0LmCHY/dVcGL/FiGfa47w1ZkAmAshLTs0kBph3sfJbaclZ8ZFmQX Ihncu+0dS4MH65XnGnFfpTgPsGYfJK3nyP7CgMkoBK1TZlyUkkmJhckdaTUQsEa8uj JUe799AOJY+lIIRUMb+IVosGBCXywSVW69PMDxi8SqwXDgpIg9Uj/zBL7+Q1w6iDPy Ma9mqkTjk0ex6G39uIRvaQOrXjqm5gMUcfMe4akW0zpzvfM/bVLmUW7OgNXqT4Bln9 2XvQq7GAoBRiw== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , will@kernel.org, maz@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, keescook@chromium.org Subject: [PATCH v4 1/2] arm64: kpti-ng: simplify page table traversal logic Date: Thu, 9 Jun 2022 16:50:09 +0200 Message-Id: <20220609145010.3602229-2-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220609145010.3602229-1-ardb@kernel.org> References: <20220609145010.3602229-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5248; h=from:subject; bh=PGV5z/hwWD/WY6LTPdcVIyvFPWs5KrYYPYO3fmfh2NY=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBiogigK1H6YwW/V9as3xy3iurfDUww1sm4G0wK8kkF hwX/kXeJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYqIIoAAKCRDDTyI5ktmPJNAhDA CQgOejmRmlU9KCN3+S8rIsYjRCoMfiHgL4q/pVl058qSp75z2L5RLbMyybntUoTliZf7Gh4LQQ3giJ Ua4XuMX9+nnvovy3GMlDrzVWsrT6gYkd3RNKLw3QaxWV47+ms81KfO69Zek/SQFcyhPQf8ufXQ1x3R 3KjihhYRiY3jGf95dhx3BNjbgfQcFFQx2ytw+tYpxszujp5+vtLzZQtuCbuTZWooQ/WlsfVzuYYwh9 xGnHWqzIQS0VA2pF6zQC5orhGgcdEOFdJL4aWH77IMzizGmvlXLwOQ5GZ604LjEskjzOD8v8V9KRde 2kQs3EW/fSAZ0sHLIF/2w8Jeqn4PqSOganP0P+Aoe7IAHyBUbUcx4COtcAFF7jNQvD0t1oislFC+YK qztzuG5erzcz1n3FsqaJJaDC3Y6jMAksKQeT0kmdemXLIwTQQ9wafJXK4gBhLDFxlfKHZ6F0tJzWC4 QhyGjnArPJYmZCOMJafj2aO5oQUSLrr59mlQgiNcJfpXo= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220609_075021_793649_7ED1431D X-CRM114-Status: GOOD ( 15.23 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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; - folding the descriptor pointer increment into the LDR instructions. 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 Reviewed-by: Mark Rutland Tested-by: Mark Rutland --- arch/arm64/mm/proc.S | 100 +++++++------------- 1 file changed, 36 insertions(+), 64 deletions(-) diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 50bbed947bec..660887152dba 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -202,19 +202,25 @@ SYM_FUNC_END(idmap_cpu_replace_ttbr1) #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 .pushsection ".idmap.text", "awx" - .macro __idmap_kpti_get_pgtable_ent, type - dc cvac, cur_\()\type\()p // Ensure any existing dirty + .macro kpti_mk_tbl_ng, type, num_entries + add end_\type\()p, cur_\type\()p, #\num_entries * 8 +.Ldo_\type: + dc cvac, cur_\type\()p // Ensure any existing dirty dmb sy // lines are written back before - ldr \type, [cur_\()\type\()p] // loading the entry - tbz \type, #0, skip_\()\type // Skip invalid and - tbnz \type, #11, skip_\()\type // non-global entries - .endm - - .macro __idmap_kpti_put_pgtable_ent_ng, type + ldr \type, [cur_\type\()p] // loading the entry + tbz \type, #0, .Lnext_\type // Skip invalid and + tbnz \type, #11, .Lnext_\type // non-global entries orr \type, \type, #PTE_NG // Same bit for blocks and pages - str \type, [cur_\()\type\()p] // Update the entry and ensure + str \type, [cur_\type\()p] // Update the entry and ensure dmb sy // that it is visible to all dc civac, cur_\()\type\()p // CPUs. + .ifnc \type, pte + tbnz \type, #1, .Lderef_\type + .endif +.Lnext_\type: + add cur_\type\()p, cur_\type\()p, #8 + cmp cur_\type\()p, end_\type\()p + b.ne .Ldo_\type .endm /* @@ -235,10 +241,8 @@ SYM_FUNC_START(idmap_kpti_install_ng_mappings) pgd .req x7 cur_pudp .req x8 end_pudp .req x9 - pud .req x10 cur_pmdp .req x11 end_pmdp .req x12 - pmd .req x13 cur_ptep .req x14 end_ptep .req x15 pte .req x16 @@ -265,16 +269,8 @@ SYM_FUNC_START(idmap_kpti_install_ng_mappings) /* Everybody is enjoying the idmap, so we can rewrite swapper. */ /* PGD */ - mov cur_pgdp, swapper_pa - add end_pgdp, cur_pgdp, #(PTRS_PER_PGD * 8) -do_pgd: __idmap_kpti_get_pgtable_ent pgd - tbnz pgd, #1, walk_puds -next_pgd: - __idmap_kpti_put_pgtable_ent_ng pgd -skip_pgd: - add cur_pgdp, cur_pgdp, #8 - cmp cur_pgdp, end_pgdp - b.ne do_pgd + mov cur_pgdp, swapper_pa + kpti_mk_tbl_ng pgd, PTRS_PER_PGD /* Publish the updated tables and nuke all the TLBs */ dsb sy @@ -291,59 +287,35 @@ skip_pgd: str wzr, [flag_ptr] ret +.Lderef_pgd: /* PUD */ -walk_puds: - .if CONFIG_PGTABLE_LEVELS > 3 + .if CONFIG_PGTABLE_LEVELS > 3 + pud .req x10 pte_to_phys cur_pudp, pgd - add end_pudp, cur_pudp, #(PTRS_PER_PUD * 8) -do_pud: __idmap_kpti_get_pgtable_ent pud - tbnz pud, #1, walk_pmds -next_pud: - __idmap_kpti_put_pgtable_ent_ng pud -skip_pud: - add cur_pudp, cur_pudp, 8 - cmp cur_pudp, end_pudp - b.ne do_pud - b next_pgd - .else /* CONFIG_PGTABLE_LEVELS <= 3 */ - mov pud, pgd - b walk_pmds -next_pud: - b next_pgd + kpti_mk_tbl_ng pud, PTRS_PER_PUD + b .Lnext_pgd + .else /* CONFIG_PGTABLE_LEVELS <= 3 */ + pud .req pgd + .set .Lnext_pud, .Lnext_pgd .endif +.Lderef_pud: /* PMD */ -walk_pmds: - .if CONFIG_PGTABLE_LEVELS > 2 + .if CONFIG_PGTABLE_LEVELS > 2 + pmd .req x13 pte_to_phys cur_pmdp, pud - add end_pmdp, cur_pmdp, #(PTRS_PER_PMD * 8) -do_pmd: __idmap_kpti_get_pgtable_ent pmd - tbnz pmd, #1, walk_ptes -next_pmd: - __idmap_kpti_put_pgtable_ent_ng pmd -skip_pmd: - add cur_pmdp, cur_pmdp, #8 - cmp cur_pmdp, end_pmdp - b.ne do_pmd - b next_pud - .else /* CONFIG_PGTABLE_LEVELS <= 2 */ - mov pmd, pud - b walk_ptes -next_pmd: - b next_pud + kpti_mk_tbl_ng pmd, PTRS_PER_PMD + b .Lnext_pud + .else /* CONFIG_PGTABLE_LEVELS <= 2 */ + pmd .req pgd + .set .Lnext_pmd, .Lnext_pgd .endif +.Lderef_pmd: /* PTE */ -walk_ptes: pte_to_phys cur_ptep, pmd - add end_ptep, cur_ptep, #(PTRS_PER_PTE * 8) -do_pte: __idmap_kpti_get_pgtable_ent pte - __idmap_kpti_put_pgtable_ent_ng pte -skip_pte: - add cur_ptep, cur_ptep, #8 - cmp cur_ptep, end_ptep - b.ne do_pte - b next_pmd + kpti_mk_tbl_ng pte, PTRS_PER_PTE + b .Lnext_pmd .unreq cpu .unreq num_cpus