From: Brian Gerst <brgerst@xxxxxxxxx> Given its CPU#, each CPU can find its own per-cpu offset, and directly set GSBASE accordingly. The global variable can be eliminated. Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx> Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Tested-by: Usama Arif <usama.arif@xxxxxxxxxxxxx> Signed-off-by: Usama Arif <usama.arif@xxxxxxxxxxxxx> Tested-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx> --- arch/x86/include/asm/realmode.h | 1 - arch/x86/kernel/acpi/sleep.c | 1 - arch/x86/kernel/head_64.S | 22 ++++++++-------------- arch/x86/kernel/smpboot.c | 2 -- 4 files changed, 8 insertions(+), 18 deletions(-) diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index a336feef0af1..f6a1737c77be 100644 --- a/arch/x86/include/asm/realmode.h +++ b/arch/x86/include/asm/realmode.h @@ -59,7 +59,6 @@ extern struct real_mode_header *real_mode_header; extern unsigned char real_mode_blob_end[]; extern unsigned long initial_code; -extern unsigned long initial_gs; extern unsigned long initial_stack; #ifdef CONFIG_AMD_MEM_ENCRYPT extern unsigned long initial_vc_handler; diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c index de89bb4719d0..1328c221af30 100644 --- a/arch/x86/kernel/acpi/sleep.c +++ b/arch/x86/kernel/acpi/sleep.c @@ -127,7 +127,6 @@ int x86_acpi_suspend_lowlevel(void) * value is in the actual %rsp register. */ current->thread.sp = (unsigned long)temp_stack + sizeof(temp_stack); - initial_gs = per_cpu_offset(smp_processor_id()); smpboot_control = smp_processor_id(); #endif initial_code = (unsigned long)wakeup_long64; diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index a5b46c2fba05..6a8238702eab 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -66,18 +66,10 @@ SYM_CODE_START_NOALIGN(startup_64) leaq _text(%rip), %rdi - /* - * initial_gs points to initial fixed_percpu_data struct with storage for - * the stack protector canary. Global pointer fixups are needed at this - * stage, so apply them as is done in fixup_pointer(), and initialize %gs - * such that the canary can be accessed at %gs:40 for subsequent C calls. - */ + /* Setup GSBASE to allow stack canary access for C code */ movl $MSR_GS_BASE, %ecx - movq initial_gs(%rip), %rax - movq $_text, %rdx - subq %rdx, %rax - addq %rdi, %rax - movq %rax, %rdx + leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx + movl %edx, %eax shrq $32, %rdx wrmsr @@ -294,8 +286,11 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) * the per cpu areas are set up. */ movl $MSR_GS_BASE,%ecx - movl initial_gs(%rip),%eax - movl initial_gs+4(%rip),%edx +#ifndef CONFIG_SMP + leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx +#endif + movl %edx, %eax + shrq $32, %rdx wrmsr /* Setup and Load IDT */ @@ -437,7 +432,6 @@ SYM_CODE_END(vc_boot_ghcb) __REFDATA .balign 8 SYM_DATA(initial_code, .quad x86_64_start_kernel) -SYM_DATA(initial_gs, .quad INIT_PER_CPU_VAR(fixed_percpu_data)) #ifdef CONFIG_AMD_MEM_ENCRYPT SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb) #endif diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 67224e61310c..28d1643eee99 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1084,8 +1084,6 @@ int common_cpu_up(unsigned int cpu, struct task_struct *idle) #ifdef CONFIG_X86_32 /* Stack for startup_32 can be just as for start_secondary onwards */ per_cpu(pcpu_hot.top_of_stack, cpu) = task_top_of_stack(idle); -#else - initial_gs = per_cpu_offset(cpu); #endif return 0; } -- 2.25.1
