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Wed, 24 Feb 2021 23:33:50 -0800 (PST) Received: from sc2-haas01-esx0118.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id w3sm4917561pjt.24.2021.02.24.23.33.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Feb 2021 23:33:50 -0800 (PST) From: Nadav Amit X-Google-Original-From: Nadav Amit To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hugh Dickins , Andy Lutomirski , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Borislav Petkov , Nadav Amit , Sean Christopherson , Andrew Morton , x86@kernel.org Subject: [RFC 2/6] x86/vdso: add mask and flags to extable Date: Wed, 24 Feb 2021 23:29:06 -0800 Message-Id: <20210225072910.2811795-3-namit@vmware.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210225072910.2811795-1-namit@vmware.com> References: <20210225072910.2811795-1-namit@vmware.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: BAC81A0009D1 X-Stat-Signature: fw81q8bkkpkwwo7j4cjupxhu8yn1ebpi Received-SPF: none (<>: No applicable sender policy available) receiver=imf24; identity=mailfrom; envelope-from="<>"; helo=mail-pg1-f182.google.com; client-ip=209.85.215.182 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614238426-643960 Content-Transfer-Encoding: quoted-printable 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: From: Nadav Amit Add a "mask" field to vDSO exception tables that says which exceptions should be handled. Add a "flags" field to vDSO as well to provide additional information about the exception. The existing preprocessor macro _ASM_VDSO_EXTABLE_HANDLE for assembly is not easy to use as it requires the user to stringify the expanded C macro. Remove _ASM_VDSO_EXTABLE_HANDLE and use a similar scheme to ALTERNATIVE, using assembly macros directly in assembly without wrapping them in C macros. Move the vsgx supported exceptions test out of the generic C code into vsgx-specific assembly by setting vsgx supported exceptions in the mask. Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Sean Christopherson Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Andrew Morton Cc: x86@kernel.org Signed-off-by: Nadav Amit --- arch/x86/entry/vdso/extable.c | 9 +-------- arch/x86/entry/vdso/extable.h | 21 +++++++++++++-------- arch/x86/entry/vdso/vsgx.S | 9 +++++++-- 3 files changed, 21 insertions(+), 18 deletions(-) diff --git a/arch/x86/entry/vdso/extable.c b/arch/x86/entry/vdso/extable.= c index c81e78636220..93fb37bd32ad 100644 --- a/arch/x86/entry/vdso/extable.c +++ b/arch/x86/entry/vdso/extable.c @@ -7,6 +7,7 @@ =20 struct vdso_exception_table_entry { int insn, fixup; + unsigned int mask, flags; }; =20 bool fixup_vdso_exception(struct pt_regs *regs, int trapnr, @@ -17,14 +18,6 @@ bool fixup_vdso_exception(struct pt_regs *regs, int tr= apnr, unsigned int nr_entries, i; unsigned long base; =20 - /* - * Do not attempt to fixup #DB or #BP. It's impossible to identify - * whether or not a #DB/#BP originated from within an SGX enclave and - * SGX enclaves are currently the only use case for vDSO fixup. - */ - if (trapnr =3D=3D X86_TRAP_DB || trapnr =3D=3D X86_TRAP_BP) - return false; - if (!current->mm->context.vdso) return false; =20 diff --git a/arch/x86/entry/vdso/extable.h b/arch/x86/entry/vdso/extable.= h index b56f6b012941..7ca8a0776805 100644 --- a/arch/x86/entry/vdso/extable.h +++ b/arch/x86/entry/vdso/extable.h @@ -2,26 +2,31 @@ #ifndef __VDSO_EXTABLE_H #define __VDSO_EXTABLE_H =20 +#include + +#define ASM_VDSO_ASYNC_FLAGS (1 << 0) + /* * Inject exception fixup for vDSO code. Unlike normal exception fixup, * vDSO uses a dedicated handler the addresses are relative to the overa= ll * exception table, not each individual entry. */ #ifdef __ASSEMBLY__ -#define _ASM_VDSO_EXTABLE_HANDLE(from, to) \ - ASM_VDSO_EXTABLE_HANDLE from to - -.macro ASM_VDSO_EXTABLE_HANDLE from:req to:req +.macro ASM_VDSO_EXTABLE_HANDLE from:req to:req mask:req flags:req .pushsection __ex_table, "a" .long (\from) - __ex_table .long (\to) - __ex_table + .long (\mask) + .long (\flags) .popsection .endm #else -#define _ASM_VDSO_EXTABLE_HANDLE(from, to) \ - ".pushsection __ex_table, \"a\"\n" \ - ".long (" #from ") - __ex_table\n" \ - ".long (" #to ") - __ex_table\n" \ +#define ASM_VDSO_EXTABLE_HANDLE(from, to, mask, flags) \ + ".pushsection __ex_table, \"a\"\n" \ + ".long (" #from ") - __ex_table\n" \ + ".long (" #to ") - __ex_table\n" \ + ".long (" #mask ")\n" \ + ".long (" #flags ")\n" \ ".popsection\n" #endif =20 diff --git a/arch/x86/entry/vdso/vsgx.S b/arch/x86/entry/vdso/vsgx.S index 86a0e94f68df..c588255af480 100644 --- a/arch/x86/entry/vdso/vsgx.S +++ b/arch/x86/entry/vdso/vsgx.S @@ -4,6 +4,7 @@ #include #include #include +#include =20 #include "extable.h" =20 @@ -146,6 +147,10 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave) =20 .cfi_endproc =20 -_ASM_VDSO_EXTABLE_HANDLE(.Lenclu_eenter_eresume, .Lhandle_exception) - +/* + * Do not attempt to fixup #DB or #BP. It's impossible to identify + * whether or not a #DB/#BP originated from within an SGX enclave. + */ +ASM_VDSO_EXTABLE_HANDLE .Lenclu_eenter_eresume, .Lhandle_exception, \ + ~((1<