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From:   "Hou Wenlong" <houwenlong.hwl@antgroup.com>
To:     linux-kernel@vger.kernel.org
Cc:     "Thomas Garnier" <thgarnie@chromium.org>,
        "Lai Jiangshan" <jiangshan.ljs@antgroup.com>,
        "Kees Cook" <keescook@chromium.org>,
        "Hou Wenlong" <houwenlong.hwl@antgroup.com>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>,
        "Dave Hansen" <dave.hansen@linux.intel.com>, <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH RFC 12/43] x86,rethook: Adapt assembly for PIE support
Date:   Fri, 28 Apr 2023 17:50:52 +0800
Message-Id: <8a0c7ca2d70bbc6162c97a87a73dafb24a6659a2.1682673543.git.houwenlong.hwl@antgroup.com>
In-Reply-To: <cover.1682673542.git.houwenlong.hwl@antgroup.com>
References: <cover.1682673542.git.houwenlong.hwl@antgroup.com>
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Change the assembly code to use only relative references of symbols for
the kernel to be PIE compatible.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Cc: Thomas Garnier <thgarnie@chromium.org>
Cc: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Cc: Kees Cook <keescook@chromium.org>
---
 arch/x86/kernel/rethook.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c
index 8a1c0111ae79..ff3733b765e0 100644
--- a/arch/x86/kernel/rethook.c
+++ b/arch/x86/kernel/rethook.c
@@ -27,7 +27,15 @@ asm(
 #ifdef CONFIG_X86_64
 	ANNOTATE_NOENDBR	/* This is only jumped from ret instruction */
 	/* Push a fake return address to tell the unwinder it's a rethook. */
+#ifdef CONFIG_X86_PIE
+	"	pushq $0\n"
+	"	pushq %rdi\n"
+	"	leaq arch_rethook_trampoline(%rip), %rdi\n"
+	"	movq %rdi, 8(%rsp)\n"
+	"	popq %rdi\n"
+#else
 	"	pushq $arch_rethook_trampoline\n"
+#endif
 	UNWIND_HINT_FUNC
 	"       pushq $" __stringify(__KERNEL_DS) "\n"
 	/* Save the 'sp - 16', this will be fixed later. */
-- 
2.31.1