linux-kernel - [RFC PATCH v2 12/16] x86/kexec: Mark relocate

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Message-ID: <20241122224715.171751-13-dwmw2@infradead.org>
Date: Fri, 22 Nov 2024 22:38:21 +0000
From: David Woodhouse <dwmw2@...radead.org>
To: kexec@...ts.infradead.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	David Woodhouse <dwmw@...zon.co.uk>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Kai Huang <kai.huang@...el.com>,
	Nikolay Borisov <nik.borisov@...e.com>,
	linux-kernel@...r.kernel.org,
	Simon Horman <horms@...nel.org>,
	Dave Young <dyoung@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	jpoimboe@...nel.org
Subject: [RFC PATCH v2 12/16] x86/kexec: Mark relocate_kernel page as ROX instead of RWX

From: David Woodhouse <dwmw@...zon.co.uk>

All writes to the page now happen before it gets marked as executable
(or after it's already switched to the identmap page tables where it's
OK to be RWX).

Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
---
 arch/x86/kernel/machine_kexec_64.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index c653c2c22d63..2a294daeeb1a 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -319,7 +319,7 @@ int machine_kexec_prepare(struct kimage *image)
 
 	__memcpy(control_page, __relocate_kernel_start, reloc_end - reloc_start);
 
-	set_memory_x((unsigned long)control_page, 1);
+	set_memory_rox((unsigned long)control_page, 1);
 
 	return 0;
 }
@@ -329,6 +329,7 @@ void machine_kexec_cleanup(struct kimage *image)
 	void *control_page = page_address(image->control_code_page) + PAGE_SIZE;
 
 	set_memory_nx((unsigned long)control_page, 1);
+	set_memory_rw((unsigned long)control_page, 1);
 
 	free_transition_pgtable(image);
 }
-- 
2.47.0