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Peter Anvin" From: Maciej Wieczor-Retman Cc: m.wieczorretman@pm.me, Maciej Wieczor-Retman , linux-kernel@vger.kernel.org Subject: [PATCH v7 07/15] x86/mm: Physical address comparisons in fill_p*d/pte Message-ID: In-Reply-To: References: Feedback-ID: 164464600:user:proton X-Pm-Message-ID: 1deacf41134359a53e7c7ed65d546b96e245276b Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Maciej Wieczor-Retman Calculating page offset returns a pointer without a tag. When comparing the calculated offset to a tagged page pointer an error is raised because they are not equal. Change pointer comparisons to physical address comparisons as to avoid issues with tagged pointers that pointer arithmetic would create. Open code pte_offset_kernel(), pmd_offset(), pud_offset() and p4d_offset(). Because one parameter is always zero and the rest of the function insides are enclosed inside __va(), removing that layer lowers the complexity of final assembly. Signed-off-by: Maciej Wieczor-Retman --- Changelog v7: - Swap ternary operator outcomes in fill_p4d since the order was incorrect. Changelog v2: - Open code *_offset() to avoid it's internal __va(). arch/x86/mm/init_64.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 0e4270e20fad..ae173f8c2aa7 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -269,7 +269,10 @@ static p4d_t *fill_p4d(pgd_t *pgd, unsigned long vaddr) if (pgd_none(*pgd)) { p4d_t *p4d =3D (p4d_t *)spp_getpage(); pgd_populate(&init_mm, pgd, p4d); - if (p4d !=3D p4d_offset(pgd, 0)) + + if (__pa(p4d) !=3D (pgtable_l5_enabled() ? + (unsigned long)pgd_val(*pgd) & PTE_PFN_MASK : + __pa(pgd))) printk(KERN_ERR "PAGETABLE BUG #00! %p <-> %p\n", p4d, p4d_offset(pgd, 0)); } @@ -281,7 +284,7 @@ static pud_t *fill_pud(p4d_t *p4d, unsigned long vaddr) if (p4d_none(*p4d)) { pud_t *pud =3D (pud_t *)spp_getpage(); p4d_populate(&init_mm, p4d, pud); - if (pud !=3D pud_offset(p4d, 0)) + if (__pa(pud) !=3D (p4d_val(*p4d) & p4d_pfn_mask(*p4d))) printk(KERN_ERR "PAGETABLE BUG #01! %p <-> %p\n", pud, pud_offset(p4d, 0)); } @@ -293,7 +296,7 @@ static pmd_t *fill_pmd(pud_t *pud, unsigned long vaddr) if (pud_none(*pud)) { pmd_t *pmd =3D (pmd_t *) spp_getpage(); pud_populate(&init_mm, pud, pmd); - if (pmd !=3D pmd_offset(pud, 0)) + if (__pa(pmd) !=3D (pud_val(*pud) & pud_pfn_mask(*pud))) printk(KERN_ERR "PAGETABLE BUG #02! %p <-> %p\n", pmd, pmd_offset(pud, 0)); } @@ -305,7 +308,7 @@ static pte_t *fill_pte(pmd_t *pmd, unsigned long vaddr) if (pmd_none(*pmd)) { pte_t *pte =3D (pte_t *) spp_getpage(); pmd_populate_kernel(&init_mm, pmd, pte); - if (pte !=3D pte_offset_kernel(pmd, 0)) + if (__pa(pte) !=3D (pmd_val(*pmd) & pmd_pfn_mask(*pmd))) printk(KERN_ERR "PAGETABLE BUG #03!\n"); } return pte_offset_kernel(pmd, vaddr); --=20 2.52.0