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Peter Anvin" , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonas Bonn , Stefan Kristiansson , Stafford Horne Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-openrisc@vger.kernel.org X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4366; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=zbP/UAv5r1ecRg6w3p/1fVSqT9+jMUkB+linIaJOv8Q=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqsQ1Olg/kp2O12ZhBFsprJTLwJprUFHtBPBboc xsbot1EFYuJAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCarENTgAKCRBt1cPRWsUx M9M0C/4omPEQYtMsmhr5u98NEFHzremiNZ24+AVOBDXTL+rJoYL/1w6it+HEgBZjKKRb1YpvT5a xzVvByW0NmxLHkS1C/N1PMUe8Y4v1TxJUnTrrnnujUMcyWrEjMVbDul0gKHFZJsIXo+Y5jCHcE8 o7nstAfRNVP0jsYT4A0swLzAVx82gz5mYQ9xbh1mvQIC8KGwW0HSzesy8GLGafXd4rTpmQhp6c8 FIvu17DbNJG43dukNhzi2rTu0HGYqn2GG7Z6DQ5d3QCZZkjBTHhShsHvtYmvxdbOeKHOXh34xXq 2paWtI/ipWGZ/zqFv/TF15VlryOyvMcF4ZNYvUKCQrvfZvgnZ/l2mgiF4a6HTWXFYeGFlewj6nz rgP6hVmN51A2FA5SEUKAcs21tcP99SeU25vHkI6TW3ad9swA9i/BHG5yftJwbr4dwszKeFahtQj qg9S4LKfbCjV8hC8w7FbIuTX6eIY1qUH6i70JIks3i9F1KNAtzfUAu+vIDSiAVc5xY52s= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 49CDA1C0005 X-Stat-Signature: ste4gqmp7co771hbm4kcdfidaufbsexc X-HE-Tag: 1789988242-243356 X-HE-Meta: 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 hfxhYKMT wSSOkZLfJbp2IYlIKwWRwuTF4ppnrmbrIRGLsylHbXHYmUeqsChOJQUZDYTRwen3f36Z5RAv6I8iUKFfLGKbkzL4gq8xHOStm3Oh8aXrMIHoIhGCAMcgSJMeTpynZyMNeGSPLkkohqVg+mi0dy+d8Rg9PDBGTiEKv35stvZn6qZW0yuwtRoRBEognSn8YPDyYkF/1s6a4q7h28Df2iIOEzBlWcEXV9ROa9VT5Bi/PN1mtDNBH0rZh7sbuvT69CsiW+nERWqd42IVjbXs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "David Hildenbrand (Arm)" The default helpers fallback to pud_offset(), passing a pointer to the stack value. Let's provide variants that do exactly what (pgd|p4d|pud)_offset() do, but ignore the passed pgd_t/p4d_t/pud_t, consequently not working on a pointer to the stack value like the default handlers would. With this patch, Drop the arm64 custom variant that did that. As it documents: Note: reusing the original pointer means that it may be dereferenced the same (live) page-table entry multiple times. This is safe because it is still only loaded once in the context of each level and the CPU guarantees same-address read-after-read ordering. Do not document this, as the double read will be removed in the next patch. Signed-off-by: David Hildenbrand (Arm) --- arch/arm64/include/asm/pgtable.h | 23 ----------------------- include/asm-generic/pgtable-nop4d.h | 7 +++++++ include/asm-generic/pgtable-nopmd.h | 7 +++++++ include/asm-generic/pgtable-nopud.h | 7 +++++++ 4 files changed, 21 insertions(+), 23 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e89ec5f4787b4..a3c882e46777a 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -1180,29 +1180,6 @@ static inline bool pgtable_l5_enabled(void) { return false; } #define p4d_clear_fixmap() #define p4d_offset_kimg(dir,addr) ((p4d_t *)dir) - -static inline -p4d_t *p4d_offset_lockless_folded(pgd_t *pgdp, pgd_t pgd, unsigned long addr) -{ - /* - * With runtime folding of the pud, pud_offset_lockless() passes - * the 'pgd_t *' we return here to p4d_to_folded_pud(), which - * will offset the pointer assuming that it points into - * a page-table page. However, the fast GUP path passes us a - * pgd_t allocated on the stack and so we must use the original - * pointer in 'pgdp' to construct the p4d pointer instead of - * using the generic p4d_offset_lockless() implementation. - * - * Note: reusing the original pointer means that we may - * dereference the same (live) page-table entry multiple times. - * This is safe because it is still only loaded once in the - * context of each level and the CPU guarantees same-address - * read-after-read ordering. - */ - return p4d_offset(pgdp, addr); -} -#define p4d_offset_lockless p4d_offset_lockless_folded - #endif /* CONFIG_PGTABLE_LEVELS > 4 */ #define pgd_set_fixmap(addr) ((pgd_t *)set_fixmap_offset(FIX_PGD, addr)) diff --git a/include/asm-generic/pgtable-nop4d.h b/include/asm-generic/pgtable-nop4d.h index c6a5a43899b50..019c3f074b771 100644 --- a/include/asm-generic/pgtable-nop4d.h +++ b/include/asm-generic/pgtable-nop4d.h @@ -39,6 +39,13 @@ static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address) return (p4d_t *)pgd; } +static inline p4d_t *p4d_offset_lockless(pgd_t *pgdp, pgd_t pgd, + unsigned long address) +{ + return (p4d_t *)pgdp; +} +#define p4d_offset_lockless p4d_offset_lockless + #define p4d_val(x) (pgd_val((x).pgd)) #define __p4d(x) ((p4d_t) { __pgd(x) }) diff --git a/include/asm-generic/pgtable-nopmd.h b/include/asm-generic/pgtable-nopmd.h index 4e5aaf253b6a5..1dd5b165234be 100644 --- a/include/asm-generic/pgtable-nopmd.h +++ b/include/asm-generic/pgtable-nopmd.h @@ -49,6 +49,13 @@ static inline pmd_t * pmd_offset(pud_t * pud, unsigned long address) } #define pmd_offset pmd_offset +static inline pmd_t *pmd_offset_lockless(pud_t *pudp, pud_t pud, + unsigned long address) +{ + return (pmd_t *)pudp; +} +#define pmd_offset_lockless pmd_offset_lockless + #define pmd_val(x) (pud_val((x).pud)) #define __pmd(x) ((pmd_t) { __pud(x) } ) diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h index 6c9bca78047c4..5a2b0a81ae197 100644 --- a/include/asm-generic/pgtable-nopud.h +++ b/include/asm-generic/pgtable-nopud.h @@ -47,6 +47,13 @@ static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address) } #define pud_offset pud_offset +static inline pud_t *pud_offset_lockless(p4d_t *p4dp, p4d_t p4d, + unsigned long address) +{ + return (pud_t *)p4dp; +} +#define pud_offset_lockless pud_offset_lockless + #define pud_val(x) (p4d_val((x).p4d)) #define __pud(x) ((pud_t) { __p4d(x) }) -- 2.43.0