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authorXin Li <xin3.li@intel.com>2023-03-21 23:17:58 -0700
committerThomas Gleixner <tglx@linutronix.de>2023-08-08 09:31:43 +0200
commit39163d5479285a36522b6e8f9cc568cc4987db08 (patch)
tree60381ff5e9234da868a1b48de46862b54b9b85ca /arch
parentbee6cf1a80b54548a039e224c651bb15b644a480 (diff)
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x86/vdso: Choose the right GDT_ENTRY_CPUNODE for 32-bit getcpu() on 64-bit kernel
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@intel.com> Reported-by: Shan Kang <shan.kang@intel.com> Signed-off-by: Xin Li <xin3.li@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230322061758.10639-1-xin3.li@intel.com Link: https://lore.kernel.org/oe-lkp/202303020903.b01fd1de-yujie.liu@intel.com
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/segment.h2
1 files changed, 1 insertions, 1 deletions
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:
*