This is a note to let you know that I've just added the patch titled
x86/vdso: Choose the right GDT_ENTRY_CPUNODE for 32-bit getcpu() on 64-bit kernel
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-vdso-choose-the-right-gdt_entry_cpunode-for-32-bit-getcpu-on-64-bit-kernel.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 39163d5479285a36522b6e8f9cc568cc4987db08 Mon Sep 17 00:00:00 2001
From: Xin Li <xin3.li@xxxxxxxxx>
Date: Tue, 21 Mar 2023 23:17:58 -0700
Subject: x86/vdso: Choose the right GDT_ENTRY_CPUNODE for 32-bit getcpu() on 64-bit kernel
From: Xin Li <xin3.li@xxxxxxxxx>
commit 39163d5479285a36522b6e8f9cc568cc4987db08 upstream.
The vDSO getcpu() reads CPU ID from the GDT_ENTRY_CPUNODE entry when the RDPID
instruction is not available. And GDT_ENTRY_CPUNODE is defined as 28 on 32-bit
Linux kernel and 15 on 64-bit. But the 32-bit getcpu() on 64-bit Linux kernel
is compiled with 32-bit Linux kernel GDT_ENTRY_CPUNODE, i.e., 28, beyond the
64-bit Linux kernel GDT limit. Thus, it just fails _silently_.
When BUILD_VDSO32_64 is defined, choose the 64-bit Linux kernel GDT definitions
to compile the 32-bit getcpu().
Fixes: 877cff5296faa6e ("x86/vdso: Fake 32bit VDSO build on 64bit compile for vgetcpu")
Reported-by: kernel test robot <yujie.liu@xxxxxxxxx>
Reported-by: Shan Kang <shan.kang@xxxxxxxxx>
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230322061758.10639-1-xin3.li@xxxxxxxxx
Link: https://lore.kernel.org/oe-lkp/202303020903.b01fd1de-yujie.liu@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/segment.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index 794f69625780..9d6411c65920 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -56,7 +56,7 @@
#define GDT_ENTRY_INVALID_SEG 0
-#ifdef CONFIG_X86_32
+#if defined(CONFIG_X86_32) && !defined(BUILD_VDSO32_64)
/*
* The layout of the per-CPU GDT under Linux:
*
--
2.41.0
Patches currently in stable-queue which might be from xin3.li@xxxxxxxxx are
queue-6.4/x86-vdso-choose-the-right-gdt_entry_cpunode-for-32-bit-getcpu-on-64-bit-kernel.patch
