From: Eugene Syromiatnikov <esyr@redhat.com> To: Yu-cheng Yu <yu-cheng.yu@intel.com> Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, 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 <arnd@arndb.de>, Andy Lutomirski <luto@amacapital.net>, Balbir Singh <bsingharora@gmail.com>, Cyrill Gorcunov <gorcunov@gmail.com>, Dave Hansen <dave.hansen@linux.intel.com>, Florian Weimer <fweimer@redhat.com>, "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>, Jonathan Corbet <corbet@lwn.net>, Kees Cook <keescook@chromium.org>, Mike Kravetz <mike.kravetz@oracle.com>, Nadav Amit <nadav.amit@gmail.com>, Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>Peter Subject: Re: [RFC PATCH v4 3/9] x86/cet/ibt: Add IBT legacy code bitmap allocation function Date: Wed, 3 Oct 2018 21:57:06 +0200 [thread overview] Message-ID: <20181003195702.GF32759@asgard.redhat.com> (raw) In-Reply-To: <20180921150553.21016-4-yu-cheng.yu@intel.com> On Fri, Sep 21, 2018 at 08:05:47AM -0700, Yu-cheng Yu wrote: > Indirect branch tracking provides an optional legacy code bitmap > that indicates locations of non-IBT compatible code. When set, > each bit in the bitmap represents a page in the linear address is > legacy code. > > We allocate the bitmap only when the application requests it. > Most applications do not need the bitmap. > > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> > --- > arch/x86/kernel/cet.c | 45 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > > diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c > index 6adfe795d692..a65d9745af08 100644 > --- a/arch/x86/kernel/cet.c > +++ b/arch/x86/kernel/cet.c > @@ -314,3 +314,48 @@ void cet_disable_ibt(void) > wrmsrl(MSR_IA32_U_CET, r); > current->thread.cet.ibt_enabled = 0; > } > + > +int cet_setup_ibt_bitmap(void) > +{ > + u64 r; > + unsigned long bitmap; > + unsigned long size; > + > + if (!cpu_feature_enabled(X86_FEATURE_IBT)) > + return -EOPNOTSUPP; > + > + if (!current->thread.cet.ibt_bitmap_addr) { > + /* > + * Calculate size and put in thread header. > + * may_expand_vm() needs this information. > + */ > + size = TASK_SIZE / PAGE_SIZE / BITS_PER_BYTE; TASK_SIZE_MAX is likely needed here, as an application can easily switch between long an 32-bit protected mode. And then the case of a CPU that doesn't support 5LPT. > + current->thread.cet.ibt_bitmap_size = size; > + bitmap = do_mmap_locked(0, size, PROT_READ | PROT_WRITE, > + MAP_ANONYMOUS | MAP_PRIVATE, > + VM_DONTDUMP); > + > + if (bitmap >= TASK_SIZE) { Shouldn't bitmap be unmapped here? > + current->thread.cet.ibt_bitmap_size = 0; > + return -ENOMEM; > + } > + > + current->thread.cet.ibt_bitmap_addr = bitmap; > + } > + > + /* > + * Lower bits of MSR_IA32_CET_LEG_IW_EN are for IBT > + * settings. Clear lower bits even bitmap is already > + * page-aligned. > + */ > + bitmap = current->thread.cet.ibt_bitmap_addr; > + bitmap &= PAGE_MASK; In a hypothetical situation of bitmap & PAGE_MASK < bitmap that would lead to bitmap pointing to unmapped memory. A check that bitmap is sane would probably be better. > + > + /* > + * Turn on IBT legacy bitmap. > + */ > + rdmsrl(MSR_IA32_U_CET, r); > + r |= (MSR_IA32_CET_LEG_IW_EN | bitmap); > + wrmsrl(MSR_IA32_U_CET, r); > + return 0; > +} > -- > 2.17.1 >
WARNING: multiple messages have this Message-ID (diff)
From: Eugene Syromiatnikov <esyr@redhat.com> To: Yu-cheng Yu <yu-cheng.yu@intel.com> Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, 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 <arnd@arndb.de>, Andy Lutomirski <luto@amacapital.net>, Balbir Singh <bsingharora@gmail.com>, Cyrill Gorcunov <gorcunov@gmail.com>, Dave Hansen <dave.hansen@linux.intel.com>, Florian Weimer <fweimer@redhat.com>, "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>, Jonathan Corbet <corbet@lwn.net>, Kees Cook <keescook@chromium.org>, Mike Kravetz <mike.kravetz@oracle.com>, Nadav Amit <nadav.amit@gmail.com>, Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>, Peter Zijlstra <peterz@infradead.org>, Randy Dunlap <rdunlap@infradead.org>, "Ravi V. Shankar" <ravi.v.shankar@intel.com>, Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com> Subject: Re: [RFC PATCH v4 3/9] x86/cet/ibt: Add IBT legacy code bitmap allocation function Date: Wed, 3 Oct 2018 21:57:06 +0200 [thread overview] Message-ID: <20181003195702.GF32759@asgard.redhat.com> (raw) Message-ID: <20181003195706.qo5OXRE086DfYLGjTGXUAZMi6KS-uVncUsjM3ZjXYs0@z> (raw) In-Reply-To: <20180921150553.21016-4-yu-cheng.yu@intel.com> On Fri, Sep 21, 2018 at 08:05:47AM -0700, Yu-cheng Yu wrote: > Indirect branch tracking provides an optional legacy code bitmap > that indicates locations of non-IBT compatible code. When set, > each bit in the bitmap represents a page in the linear address is > legacy code. > > We allocate the bitmap only when the application requests it. > Most applications do not need the bitmap. > > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> > --- > arch/x86/kernel/cet.c | 45 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > > diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c > index 6adfe795d692..a65d9745af08 100644 > --- a/arch/x86/kernel/cet.c > +++ b/arch/x86/kernel/cet.c > @@ -314,3 +314,48 @@ void cet_disable_ibt(void) > wrmsrl(MSR_IA32_U_CET, r); > current->thread.cet.ibt_enabled = 0; > } > + > +int cet_setup_ibt_bitmap(void) > +{ > + u64 r; > + unsigned long bitmap; > + unsigned long size; > + > + if (!cpu_feature_enabled(X86_FEATURE_IBT)) > + return -EOPNOTSUPP; > + > + if (!current->thread.cet.ibt_bitmap_addr) { > + /* > + * Calculate size and put in thread header. > + * may_expand_vm() needs this information. > + */ > + size = TASK_SIZE / PAGE_SIZE / BITS_PER_BYTE; TASK_SIZE_MAX is likely needed here, as an application can easily switch between long an 32-bit protected mode. And then the case of a CPU that doesn't support 5LPT. > + current->thread.cet.ibt_bitmap_size = size; > + bitmap = do_mmap_locked(0, size, PROT_READ | PROT_WRITE, > + MAP_ANONYMOUS | MAP_PRIVATE, > + VM_DONTDUMP); > + > + if (bitmap >= TASK_SIZE) { Shouldn't bitmap be unmapped here? > + current->thread.cet.ibt_bitmap_size = 0; > + return -ENOMEM; > + } > + > + current->thread.cet.ibt_bitmap_addr = bitmap; > + } > + > + /* > + * Lower bits of MSR_IA32_CET_LEG_IW_EN are for IBT > + * settings. Clear lower bits even bitmap is already > + * page-aligned. > + */ > + bitmap = current->thread.cet.ibt_bitmap_addr; > + bitmap &= PAGE_MASK; In a hypothetical situation of bitmap & PAGE_MASK < bitmap that would lead to bitmap pointing to unmapped memory. A check that bitmap is sane would probably be better. > + > + /* > + * Turn on IBT legacy bitmap. > + */ > + rdmsrl(MSR_IA32_U_CET, r); > + r |= (MSR_IA32_CET_LEG_IW_EN | bitmap); > + wrmsrl(MSR_IA32_U_CET, r); > + return 0; > +} > -- > 2.17.1 >
next prev parent reply other threads:[~2018-10-03 19:57 UTC|newest] Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-09-21 15:05 [RFC PATCH v4 0/9] Control Flow Enforcement: Branch Tracking, PTRACE Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-09-21 15:05 ` [RFC PATCH v4 1/9] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-09-21 15:05 ` [RFC PATCH v4 2/9] x86/cet/ibt: User-mode indirect branch tracking support Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-10-03 18:58 ` Eugene Syromiatnikov 2018-10-03 18:58 ` Eugene Syromiatnikov 2018-09-21 15:05 ` [RFC PATCH v4 3/9] x86/cet/ibt: Add IBT legacy code bitmap allocation function Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-10-03 19:57 ` Eugene Syromiatnikov [this message] 2018-10-03 19:57 ` Eugene Syromiatnikov 2018-10-05 16:13 ` Yu-cheng Yu 2018-10-05 16:13 ` Yu-cheng Yu 2018-10-05 16:28 ` Andy Lutomirski 2018-10-05 16:28 ` Andy Lutomirski 2018-10-05 16:58 ` Yu-cheng Yu 2018-10-05 16:58 ` Yu-cheng Yu 2018-10-05 17:07 ` Andy Lutomirski 2018-10-05 17:07 ` Andy Lutomirski 2018-10-05 17:26 ` Eugene Syromiatnikov 2018-10-05 17:26 ` Eugene Syromiatnikov 2018-10-10 15:56 ` Yu-cheng Yu 2018-10-10 15:56 ` Yu-cheng Yu 2018-10-04 16:11 ` Andy Lutomirski 2018-10-04 16:11 ` Andy Lutomirski 2018-09-21 15:05 ` [RFC PATCH v4 4/9] mm/mmap: Add IBT bitmap size to address space limit check Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-10-03 20:21 ` Eugene Syromiatnikov 2018-10-03 20:21 ` Eugene Syromiatnikov 2018-09-21 15:05 ` [RFC PATCH v4 5/9] x86/cet/ibt: ELF header parsing for IBT Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-09-21 15:05 ` [RFC PATCH v4 6/9] x86/cet/ibt: Add arch_prctl functions " Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-10-04 13:28 ` Eugene Syromiatnikov 2018-10-04 13:28 ` Eugene Syromiatnikov 2018-10-04 15:37 ` Yu-cheng Yu 2018-10-04 15:37 ` Yu-cheng Yu 2018-10-04 16:07 ` Florian Weimer 2018-10-04 16:07 ` Florian Weimer 2018-10-04 16:12 ` Andy Lutomirski 2018-10-04 16:12 ` Andy Lutomirski 2018-10-04 16:25 ` Yu-cheng Yu 2018-10-04 16:25 ` Yu-cheng Yu 2018-10-04 16:08 ` Andy Lutomirski 2018-10-04 16:08 ` Andy Lutomirski 2018-09-21 15:05 ` [RFC PATCH v4 7/9] x86/cet/ibt: Add ENDBR to op-code-map Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-09-21 15:05 ` [RFC PATCH v4 8/9] x86: Insert endbr32/endbr64 to vDSO Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu 2018-09-21 15:05 ` [RFC PATCH v4 9/9] x86/cet: Add PTRACE interface for CET Yu-cheng Yu 2018-09-21 15:05 ` Yu-cheng Yu
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