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Shutemov" To: Dave Hansen , Andy Lutomirski , Peter Zijlstra Cc: x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Bharata B Rao , Jacob Pan , Ashok Raj , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv15 06/17] x86/uaccess: Provide untagged_addr() and remove tags before address check Date: Tue, 24 Jan 2023 01:04:49 +0300 Message-Id: <20230123220500.21077-7-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230123220500.21077-1-kirill.shutemov@linux.intel.com> References: <20230123220500.21077-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 271CDA0016 X-Stat-Signature: x716fd7e1nmzzee4615ojmyfz7u38rk1 X-Rspam-User: X-HE-Tag: 1674511536-751634 X-HE-Meta: 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 9yh6eZG8 IHjYlztaf3AdFkz4szfOIBk3vlh4GQkz8QuGltRujs1uJ95KgwnYrzxD92iVk5HOxjOleXtB8iehK3Qqe+eeTYq+HsM+rOv4h128YmngAE+bh2if9j3UOu7Wl5SBp6Q+kRFwNGn8h2ux8mU0Bn4nW7XH7U3qwYOta2KLqhtSJdJmD92kXC2+FCGYNgqpr7Xkn46P41sUOzQ2m4A1MzRDhn07gZyuV3GnxT8RXq8Y8FtlLjHr4CNYd43DVlxvPMQ3g8NggJrPZfGgoGjhV+rPt10VOeMUKuym52QMIQ5abipTEu1eyK5gLiUQzUp3bUUSWO5fsJrvMMDuiXQF+yH6RATeq2w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: untagged_addr() is a helper used by the core-mm to strip tag bits and get the address to the canonical shape based on rules of the current thread. It only handles userspace addresses. The untagging mask is stored in per-CPU variable and set on context switching to the task. The tags must not be included into check whether it's okay to access the userspace address. Strip tags in access_ok(). Signed-off-by: Kirill A. Shutemov Acked-by: Peter Zijlstra (Intel) --- arch/x86/include/asm/mmu.h | 3 +++ arch/x86/include/asm/mmu_context.h | 11 +++++++++ arch/x86/include/asm/tlbflush.h | 10 ++++++++ arch/x86/include/asm/uaccess.h | 39 ++++++++++++++++++++++++++++-- arch/x86/kernel/process.c | 3 +++ arch/x86/mm/init.c | 5 ++++ 6 files changed, 69 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index 22fc9fbf1d0a..9cac8c45a647 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -45,6 +45,9 @@ typedef struct { #ifdef CONFIG_ADDRESS_MASKING /* Active LAM mode: X86_CR3_LAM_U48 or X86_CR3_LAM_U57 or 0 (disabled) */ unsigned long lam_cr3_mask; + + /* Significant bits of the virtual address. Excludes tag bits. */ + u64 untag_mask; #endif struct mutex lock; diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index a62e70801ea8..ca2e2ffdd3c6 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -100,6 +100,12 @@ static inline unsigned long mm_lam_cr3_mask(struct mm_struct *mm) static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm) { mm->context.lam_cr3_mask = oldmm->context.lam_cr3_mask; + mm->context.untag_mask = oldmm->context.untag_mask; +} + +static inline void mm_reset_untag_mask(struct mm_struct *mm) +{ + mm->context.untag_mask = -1UL; } #else @@ -112,6 +118,10 @@ static inline unsigned long mm_lam_cr3_mask(struct mm_struct *mm) static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm) { } + +static inline void mm_reset_untag_mask(struct mm_struct *mm) +{ +} #endif #define enter_lazy_tlb enter_lazy_tlb @@ -138,6 +148,7 @@ static inline int init_new_context(struct task_struct *tsk, mm->context.execute_only_pkey = -1; } #endif + mm_reset_untag_mask(mm); init_new_context_ldt(mm); return 0; } diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index e8b47f57bd4a..75bfaa421030 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -54,6 +54,15 @@ static inline void cr4_clear_bits(unsigned long mask) local_irq_restore(flags); } +#ifdef CONFIG_ADDRESS_MASKING +DECLARE_PER_CPU(u64, tlbstate_untag_mask); + +static inline u64 current_untag_mask(void) +{ + return this_cpu_read(tlbstate_untag_mask); +} +#endif + #ifndef MODULE /* * 6 because 6 should be plenty and struct tlb_state will fit in two cache @@ -380,6 +389,7 @@ static inline void set_tlbstate_lam_mode(struct mm_struct *mm) { this_cpu_write(cpu_tlbstate.lam, mm->context.lam_cr3_mask >> X86_CR3_LAM_U57_BIT); + this_cpu_write(tlbstate_untag_mask, mm->context.untag_mask); } #else diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 1cc756eafa44..fd9182951084 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -7,11 +7,13 @@ #include #include #include +#include #include #include #include #include #include +#include #ifdef CONFIG_DEBUG_ATOMIC_SLEEP static inline bool pagefault_disabled(void); @@ -21,6 +23,39 @@ static inline bool pagefault_disabled(void); # define WARN_ON_IN_IRQ() #endif +#ifdef CONFIG_ADDRESS_MASKING +/* + * Mask out tag bits from the address. + * + * Magic with the 'sign' allows to untag userspace pointer without any branches + * while leaving kernel addresses intact. + */ +static inline unsigned long __untagged_addr(unsigned long addr, + unsigned long mask) +{ + long sign = addr >> 63; + + addr &= mask | sign; + return addr; +} + +#define untagged_addr(addr) ({ \ + u64 __addr = (__force u64)(addr); \ + __addr = __untagged_addr(__addr, current_untag_mask()); \ + (__force __typeof__(addr))__addr; \ +}) + +#define untagged_addr_remote(mm, addr) ({ \ + u64 __addr = (__force u64)(addr); \ + mmap_assert_locked(mm); \ + __addr = __untagged_addr(__addr, (mm)->context.untag_mask); \ + (__force __typeof__(addr))__addr; \ +}) + +#else +#define untagged_addr(addr) (addr) +#endif + /** * access_ok - Checks if a user space pointer is valid * @addr: User space pointer to start of block to check @@ -38,10 +73,10 @@ static inline bool pagefault_disabled(void); * Return: true (nonzero) if the memory block may be valid, false (zero) * if it is definitely invalid. */ -#define access_ok(addr, size) \ +#define access_ok(addr, size) \ ({ \ WARN_ON_IN_IRQ(); \ - likely(__access_ok(addr, size)); \ + likely(__access_ok(untagged_addr(addr), size)); \ }) #include diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 40d156a31676..ef6bde1d40d8 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -47,6 +47,7 @@ #include #include #include +#include #include "process.h" @@ -367,6 +368,8 @@ void arch_setup_new_exec(void) task_clear_spec_ssb_noexec(current); speculation_ctrl_update(read_thread_flags()); } + + mm_reset_untag_mask(current->mm); } #ifdef CONFIG_X86_IOPL_IOPERM diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index d3987359d441..be5c7d1c0265 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -1044,6 +1044,11 @@ __visible DEFINE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate) = { .cr4 = ~0UL, /* fail hard if we screw up cr4 shadow initialization */ }; +#ifdef CONFIG_ADDRESS_MASKING +DEFINE_PER_CPU(u64, tlbstate_untag_mask); +EXPORT_PER_CPU_SYMBOL(tlbstate_untag_mask); +#endif + void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache) { /* entry 0 MUST be WB (hardwired to speed up translations) */ -- 2.39.1