From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x226v3RaZNYRShTWdUtgzmW9R7GdvnVTtId0QTi558fiAsjY8vG12JFGowSio9/1GlVIFThZ0 ARC-Seal: i=1; a=rsa-sha256; t=1518709164; cv=none; d=google.com; s=arc-20160816; b=MNJBV0eRqW1tmWA2gihaH+McZis4350YDk93JaoNQuGPg2VPtFW61lgqOzw3A5NRcq ot7P6w0VtJYDlkVkLJirPsTarua55CLvIc38VYoBsrcB0assHiFtlqcoYiqdISZ1wQBD O5Z9VRaKcL9I7fJqUrlSCCFivNLL09bgNnLU4vZlatTrBN9YIRaWclHTzmbU4tH007OU +uhxxr+Vo/OtTmtmWBO7/KInyoFSOuxZSgUa/lTPkm/JXpnki4a1gIqm/G2HDJTr43ZW qOjLh4jVCJERfZrU011dzUO0rJ4S0uxbHDzQGUZmwdvwz5sGozApW2Lxs2rE8+C58aZX ZRsw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=24iI0cocbGieqvaVVVGMU947cPJJHSsGVRKP1aha8Y8=; b=pHOgKLA1xqs4U2mXJGz4gjk9p7N7rUxq4wHR65ZNvvlgNS0Xgb3PnOpKy9T932jJgo +H/lgWlJw7ogiVWk9aNiSC6VPtZY9BiKEN7cApPBPXHXXKIND9sGZhHfnKub3CkTAJ7b S1qcPA8QcZ6JlfQYynzh7Mt0YzpISCDqH8ZuawLMtRLP+8BuEltv1gQ0YZmhQT3mZAKp pE6wOzQ2RDQf4rEqjoxj1KJnl18RaPHtexGkDg5liP5YFzae19tMBIuCpXApDCNdwSAd Dy874G/5PeQDplwfski2o3xopCac1SsBHBYibva1fVnbi0BNKU2fbev5Dw1RHqYaUKFg xg/w== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Laura Abbott , Shanker Donthineni , Will Deacon Subject: [PATCH 4.15 020/202] [Variant 3/Meltdown] arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN Date: Thu, 15 Feb 2018 16:15:20 +0100 Message-Id: <20180215151713.955175657@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151712.768794354@linuxfoundation.org> References: <20180215151712.768794354@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1592481438392756670?= X-GMAIL-MSGID: =?utf-8?q?1592481981160550608?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Will Deacon Commit 27a921e75711 upstream. With the ASID now installed in TTBR1, we can re-enable ARM64_SW_TTBR0_PAN by ensuring that we switch to a reserved ASID of zero when disabling user access and restore the active user ASID on the uaccess enable path. Reviewed-by: Mark Rutland Tested-by: Laura Abbott Tested-by: Shanker Donthineni Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/Kconfig | 1 - arch/arm64/include/asm/asm-uaccess.h | 25 +++++++++++++++++-------- arch/arm64/include/asm/uaccess.h | 21 +++++++++++++++++---- arch/arm64/kernel/entry.S | 4 ++-- arch/arm64/lib/clear_user.S | 2 +- arch/arm64/lib/copy_from_user.S | 2 +- arch/arm64/lib/copy_in_user.S | 2 +- arch/arm64/lib/copy_to_user.S | 2 +- arch/arm64/mm/cache.S | 2 +- arch/arm64/xen/hypercall.S | 2 +- 10 files changed, 42 insertions(+), 21 deletions(-) --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -920,7 +920,6 @@ endif config ARM64_SW_TTBR0_PAN bool "Emulate Privileged Access Never using TTBR0_EL1 switching" - depends on BROKEN # Temporary while switch_mm is reworked help Enabling this option prevents the kernel from accessing user-space memory directly by pointing TTBR0_EL1 to a reserved --- a/arch/arm64/include/asm/asm-uaccess.h +++ b/arch/arm64/include/asm/asm-uaccess.h @@ -16,11 +16,20 @@ add \tmp1, \tmp1, #SWAPPER_DIR_SIZE // reserved_ttbr0 at the end of swapper_pg_dir msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1 isb + sub \tmp1, \tmp1, #SWAPPER_DIR_SIZE + bic \tmp1, \tmp1, #(0xffff << 48) + msr ttbr1_el1, \tmp1 // set reserved ASID + isb .endm - .macro __uaccess_ttbr0_enable, tmp1 + .macro __uaccess_ttbr0_enable, tmp1, tmp2 get_thread_info \tmp1 ldr \tmp1, [\tmp1, #TSK_TI_TTBR0] // load saved TTBR0_EL1 + mrs \tmp2, ttbr1_el1 + extr \tmp2, \tmp2, \tmp1, #48 + ror \tmp2, \tmp2, #16 + msr ttbr1_el1, \tmp2 // set the active ASID + isb msr ttbr0_el1, \tmp1 // set the non-PAN TTBR0_EL1 isb .endm @@ -31,18 +40,18 @@ alternative_if_not ARM64_HAS_PAN alternative_else_nop_endif .endm - .macro uaccess_ttbr0_enable, tmp1, tmp2 + .macro uaccess_ttbr0_enable, tmp1, tmp2, tmp3 alternative_if_not ARM64_HAS_PAN - save_and_disable_irq \tmp2 // avoid preemption - __uaccess_ttbr0_enable \tmp1 - restore_irq \tmp2 + save_and_disable_irq \tmp3 // avoid preemption + __uaccess_ttbr0_enable \tmp1, \tmp2 + restore_irq \tmp3 alternative_else_nop_endif .endm #else .macro uaccess_ttbr0_disable, tmp1 .endm - .macro uaccess_ttbr0_enable, tmp1, tmp2 + .macro uaccess_ttbr0_enable, tmp1, tmp2, tmp3 .endm #endif @@ -56,8 +65,8 @@ alternative_if ARM64_ALT_PAN_NOT_UAO alternative_else_nop_endif .endm - .macro uaccess_enable_not_uao, tmp1, tmp2 - uaccess_ttbr0_enable \tmp1, \tmp2 + .macro uaccess_enable_not_uao, tmp1, tmp2, tmp3 + uaccess_ttbr0_enable \tmp1, \tmp2, \tmp3 alternative_if ARM64_ALT_PAN_NOT_UAO SET_PSTATE_PAN(0) alternative_else_nop_endif --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -107,15 +107,19 @@ static inline void __uaccess_ttbr0_disab { unsigned long ttbr; + ttbr = read_sysreg(ttbr1_el1); /* reserved_ttbr0 placed at the end of swapper_pg_dir */ - ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE; - write_sysreg(ttbr, ttbr0_el1); + write_sysreg(ttbr + SWAPPER_DIR_SIZE, ttbr0_el1); + isb(); + /* Set reserved ASID */ + ttbr &= ~(0xffffUL << 48); + write_sysreg(ttbr, ttbr1_el1); isb(); } static inline void __uaccess_ttbr0_enable(void) { - unsigned long flags; + unsigned long flags, ttbr0, ttbr1; /* * Disable interrupts to avoid preemption between reading the 'ttbr0' @@ -123,7 +127,16 @@ static inline void __uaccess_ttbr0_enabl * roll-over and an update of 'ttbr0'. */ local_irq_save(flags); - write_sysreg(current_thread_info()->ttbr0, ttbr0_el1); + ttbr0 = current_thread_info()->ttbr0; + + /* Restore active ASID */ + ttbr1 = read_sysreg(ttbr1_el1); + ttbr1 |= ttbr0 & (0xffffUL << 48); + write_sysreg(ttbr1, ttbr1_el1); + isb(); + + /* Restore user page table */ + write_sysreg(ttbr0, ttbr0_el1); isb(); local_irq_restore(flags); } --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -184,7 +184,7 @@ alternative_if ARM64_HAS_PAN alternative_else_nop_endif .if \el != 0 - mrs x21, ttbr0_el1 + mrs x21, ttbr1_el1 tst x21, #0xffff << 48 // Check for the reserved ASID orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR b.eq 1f // TTBR0 access already disabled @@ -248,7 +248,7 @@ alternative_else_nop_endif tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set .endif - __uaccess_ttbr0_enable x0 + __uaccess_ttbr0_enable x0, x1 .if \el == 0 /* --- a/arch/arm64/lib/clear_user.S +++ b/arch/arm64/lib/clear_user.S @@ -30,7 +30,7 @@ * Alignment fixed up by hardware. */ ENTRY(__clear_user) - uaccess_enable_not_uao x2, x3 + uaccess_enable_not_uao x2, x3, x4 mov x2, x1 // save the size for fixup return subs x1, x1, #8 b.mi 2f --- a/arch/arm64/lib/copy_from_user.S +++ b/arch/arm64/lib/copy_from_user.S @@ -64,7 +64,7 @@ end .req x5 ENTRY(__arch_copy_from_user) - uaccess_enable_not_uao x3, x4 + uaccess_enable_not_uao x3, x4, x5 add end, x0, x2 #include "copy_template.S" uaccess_disable_not_uao x3 --- a/arch/arm64/lib/copy_in_user.S +++ b/arch/arm64/lib/copy_in_user.S @@ -65,7 +65,7 @@ end .req x5 ENTRY(raw_copy_in_user) - uaccess_enable_not_uao x3, x4 + uaccess_enable_not_uao x3, x4, x5 add end, x0, x2 #include "copy_template.S" uaccess_disable_not_uao x3 --- a/arch/arm64/lib/copy_to_user.S +++ b/arch/arm64/lib/copy_to_user.S @@ -63,7 +63,7 @@ end .req x5 ENTRY(__arch_copy_to_user) - uaccess_enable_not_uao x3, x4 + uaccess_enable_not_uao x3, x4, x5 add end, x0, x2 #include "copy_template.S" uaccess_disable_not_uao x3 --- a/arch/arm64/mm/cache.S +++ b/arch/arm64/mm/cache.S @@ -49,7 +49,7 @@ ENTRY(flush_icache_range) * - end - virtual end address of region */ ENTRY(__flush_cache_user_range) - uaccess_ttbr0_enable x2, x3 + uaccess_ttbr0_enable x2, x3, x4 dcache_line_size x2, x3 sub x3, x2, #1 bic x4, x0, x3 --- a/arch/arm64/xen/hypercall.S +++ b/arch/arm64/xen/hypercall.S @@ -101,7 +101,7 @@ ENTRY(privcmd_call) * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation * is enabled (it implies that hardware UAO and PAN disabled). */ - uaccess_ttbr0_enable x6, x7 + uaccess_ttbr0_enable x6, x7, x8 hvc XEN_IMM /*