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Peter Anvin" , Dave Hansen , Peter Zijlstra , Al Viro , Vincenzo Frascino , Joerg Roedel , Ricardo Neri , Reinette Chatre , Andrew Morton , Gabriel Krisman Bertazi , Kees Cook , Frederic Weisbecker , Jens Axboe , Arvind Sankar , Brian Gerst , Ard Biesheuvel , Andi Kleen , Mike Rapoport , Mike Hommey , Mark Gross , Fenghua Yu , Tony Luck , Anthony Steinhauser , Jay Lang , "Chang S. Bae" Subject: [PATCH V2 2/6] x86_32: use percpu instead of offset-calculation to get thread.sp0 when SWITCH_TO_KERNEL_STACK Date: Tue, 26 Jan 2021 01:34:30 +0800 Message-Id: <20210125173444.22696-3-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20210125173444.22696-1-jiangshanlai@gmail.com> References: <20210125173444.22696-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan TSS_entry2task_stack is used to refer to tss.sp1 which is stored the value of thread.sp0. At the code where TSS_entry2task_stack is used in SWITCH_TO_KERNEL_STACK, the CR3 is already kernel CR3 and kernel segments is loaded. So we can directly use the percpu to get tss.sp1(thread.sp0) instead of the complex offset-calculation. Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry_32.S | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index df8c017e6161..3b4d1a63d1f0 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -465,16 +465,11 @@ cmpl $SIZEOF_entry_stack, %ecx jae .Lend_\@ - /* Load stack pointer into %esi and %edi */ + /* Load stack pointer into %esi */ movl %esp, %esi - movl %esi, %edi - - /* Move %edi to the top of the entry stack */ - andl $(MASK_entry_stack), %edi - addl $(SIZEOF_entry_stack), %edi /* Load top of task-stack into %edi */ - movl TSS_entry2task_stack(%edi), %edi + movl PER_CPU_VAR(cpu_tss_rw + TSS_sp1), %edi /* Special case - entry from kernel mode via entry stack */ #ifdef CONFIG_VM86 -- 2.19.1.6.gb485710b