linux-kernel - [PATCH V2 20/41] x86/entry: Add the C version ist_switch_to_kernel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 26 Sep 2021 23:08:17 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH V2 20/41] x86/entry: Add the C version ist_switch_to_kernel_cr3()

From: Lai Jiangshan <laijs@...ux.alibaba.com>

It switches the CR3 to kernel CR3 and returns the original CR3, and
the caller should save the return value.

It is the C version of SAVE_AND_SWITCH_TO_KERNEL_CR3.

Not functional difference intended.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 arch/x86/entry/entry64.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/entry/entry64.c b/arch/x86/entry/entry64.c
index 5f2be4c3f333..faee44a3d1d8 100644
--- a/arch/x86/entry/entry64.c
+++ b/arch/x86/entry/entry64.c
@@ -32,8 +32,23 @@ static __always_inline void switch_to_kernel_cr3(void)
 	if (static_cpu_has(X86_FEATURE_PTI))
 		pti_switch_to_kernel_cr3(__native_read_cr3());
 }
+
+static __always_inline unsigned long ist_switch_to_kernel_cr3(void)
+{
+	unsigned long cr3 = 0;
+
+	if (static_cpu_has(X86_FEATURE_PTI)) {
+		cr3 = __native_read_cr3();
+
+		if (cr3 & PTI_USER_PGTABLE_MASK)
+			pti_switch_to_kernel_cr3(cr3);
+	}
+
+	return cr3;
+}
 #else
 static __always_inline void switch_to_kernel_cr3(void) {}
+static __always_inline unsigned long ist_switch_to_kernel_cr3(void) { return 0; }
 #endif
 
 /*
-- 
2.19.1.6.gb485710b