linux-kernel - [PATCH v7 04/14] x86/cet/ibt: Handle signals for IBT

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Date:   Thu,  6 Jun 2019 13:09:16 -0700
From:   Yu-cheng Yu <yu-cheng.yu@...el.com>
To:     x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...capital.net>,
        Balbir Singh <bsingharora@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
        Dave Martin <Dave.Martin@....com>
Cc:     Yu-cheng Yu <yu-cheng.yu@...el.com>
Subject: [PATCH v7 04/14] x86/cet/ibt: Handle signals for IBT

Setup/Restore Indirect Branch Tracking for signals.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
---
 arch/x86/kernel/cet.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
index e0ef996d3148..e1ab7e722637 100644
--- a/arch/x86/kernel/cet.c
+++ b/arch/x86/kernel/cet.c
@@ -282,6 +282,15 @@ int cet_restore_signal(bool ia32, struct sc_ext *sc_ext)
 		msr_ia32_u_cet |= MSR_IA32_CET_SHSTK_EN;
 	}
 
+	if (current->thread.cet.ibt_enabled) {
+		if (current->thread.cet.ibt_bitmap_addr != 0)
+			msr_ia32_u_cet |= (current->thread.cet.ibt_bitmap_addr |
+					   MSR_IA32_CET_LEG_IW_EN);
+
+		msr_ia32_u_cet |= (MSR_IA32_CET_ENDBR_EN |
+				   MSR_IA32_CET_NO_TRACK_EN);
+	}
+
 	wrmsrl(MSR_IA32_PL3_SSP, new_ssp);
 	wrmsrl(MSR_IA32_U_CET, msr_ia32_u_cet);
 	return 0;
@@ -322,6 +331,15 @@ int cet_setup_signal(bool ia32, unsigned long rstor_addr, struct sc_ext *sc_ext)
 		sc_ext->ssp = new_ssp;
 	}
 
+	if (current->thread.cet.ibt_enabled) {
+		if (current->thread.cet.ibt_bitmap_addr != 0)
+			msr_ia32_u_cet |= (current->thread.cet.ibt_bitmap_addr |
+					   MSR_IA32_CET_LEG_IW_EN);
+
+		msr_ia32_u_cet |= (MSR_IA32_CET_ENDBR_EN |
+				   MSR_IA32_CET_NO_TRACK_EN);
+	}
+
 	modify_fpu_regs_begin();
 	wrmsrl(MSR_IA32_PL3_SSP, ssp);
 	wrmsrl(MSR_IA32_U_CET, msr_ia32_u_cet);
-- 
2.17.1