From: Xin Li Date: Wed, 22 Mar 2023 06:17:58 +0000 (-0700) Subject: x86/vdso: Choose the right GDT_ENTRY_CPUNODE for 32-bit getcpu() on 64-bit kernel X-Git-Tag: v6.6.17~4218^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=39163d5479285a36522b6e8f9cc568cc4987db08;p=platform%2Fkernel%2Flinux-rpi.git 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 Reported-by: Shan Kang Signed-off-by: Xin Li Signed-off-by: Thomas Gleixner 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 --- diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index 794f696..9d6411c 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: *