From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [PATCH v8 11/14] x86/vsyscall/64: Fixup shadow stack and branch tracking for vsyscall Date: Tue, 13 Aug 2019 13:53:56 -0700 Message-ID: <20190813205359.12196-12-yu-cheng.yu@intel.com> References: <20190813205359.12196-1-yu-cheng.yu@intel.com> Return-path: In-Reply-To: <20190813205359.12196-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit Cc: Yu-cheng Yu List-Id: linux-api@vger.kernel.org When emulating a RET, also unwind the task's shadow stack and cancel the current branch tracking status. Signed-off-by: Yu-cheng Yu --- arch/x86/entry/vsyscall/vsyscall_64.c | 29 ++++++++++++++++++++++++ arch/x86/entry/vsyscall/vsyscall_trace.h | 1 + 2 files changed, 30 insertions(+) diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c index e7c596dea947..27ff81f75c82 100644 --- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -38,6 +38,9 @@ #include #include #include +#include +#include +#include #define CREATE_TRACE_POINTS #include "vsyscall_trace.h" @@ -286,6 +289,32 @@ bool emulate_vsyscall(unsigned long error_code, /* Emulate a ret instruction. */ regs->ip = caller; regs->sp += 8; + + /* Unwind shadow stack. */ + +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER + if (current->thread.cet.shstk_enabled) { + u64 r; + + modify_fpu_regs_begin(); + rdmsrl(MSR_IA32_PL3_SSP, r); + wrmsrl(MSR_IA32_PL3_SSP, r + 8); + modify_fpu_regs_end(); + } +#endif + + /* Fixup branch tracking */ +#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER + if (current->thread.cet.ibt_enabled) { + u64 r; + + modify_fpu_regs_begin(); + rdmsrl(MSR_IA32_U_CET, r); + wrmsrl(MSR_IA32_U_CET, r & ~MSR_IA32_CET_WAIT_ENDBR); + modify_fpu_regs_end(); + } +#endif + return true; sigsegv: diff --git a/arch/x86/entry/vsyscall/vsyscall_trace.h b/arch/x86/entry/vsyscall/vsyscall_trace.h index 3c3f9765a85c..7aa2101ada44 100644 --- a/arch/x86/entry/vsyscall/vsyscall_trace.h +++ b/arch/x86/entry/vsyscall/vsyscall_trace.h @@ -25,6 +25,7 @@ TRACE_EVENT(emulate_vsyscall, #endif #undef TRACE_INCLUDE_PATH +#undef TRACE_INCLUDE_FILE #define TRACE_INCLUDE_PATH ../../arch/x86/entry/vsyscall/ #define TRACE_INCLUDE_FILE vsyscall_trace #include -- 2.17.1