From b2e2ba578e016a091eb31565849990fe68c7c599 Mon Sep 17 00:00:00 2001 From: "Chang S. Bae" Date: Tue, 18 Sep 2018 16:08:59 -0700 Subject: [PATCH] x86/vdso: Initialize the CPU/node NR segment descriptor earlier Currently the CPU/node NR segment descriptor (GDT_ENTRY_CPU_NUMBER) is initialized relatively late during CPU init, from the vCPU code, which has a number of disadvantages, such as hotplug CPU notifiers and SMP cross-calls. Instead just initialize it much earlier, directly in cpu_init(). This reduces complexity and increases robustness. [ mingo: Wrote new changelog. ] Suggested-by: H. Peter Anvin Suggested-by: Andy Lutomirski Signed-off-by: Chang S. Bae Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Linus Torvalds Cc: Markus T Metzger Cc: Peter Zijlstra Cc: Ravi Shankar Cc: Rik van Riel Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1537312139-5580-9-git-send-email-chang.seok.bae@intel.com Signed-off-by: Ingo Molnar --- arch/x86/entry/vdso/vma.c | 33 +-------------------------------- arch/x86/kernel/cpu/common.c | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+), 32 deletions(-) diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 39b5584c5808..3f9d43f26f63 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -332,35 +332,6 @@ static __init int vdso_setup(char *s) return 0; } __setup("vdso=", vdso_setup); -#endif - -#ifdef CONFIG_X86_64 -static void vgetcpu_cpu_init(void *arg) -{ - int cpu = smp_processor_id(); - struct desc_struct d = { }; - unsigned long cpudata = vdso_encode_cpu_node(cpu, cpu_to_node(cpu)); - - if (static_cpu_has(X86_FEATURE_RDTSCP)) - write_rdtscp_aux(cpudata); - - /* Store CPU and node number in limit */ - d.limit0 = cpudata; - d.limit1 = cpudata >> 16; - - d.type = 5; /* RO data, expand down, accessed */ - d.dpl = 3; /* Visible to user code */ - d.s = 1; /* Not a system segment */ - d.p = 1; /* Present */ - d.d = 1; /* 32-bit */ - - write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_CPU_NUMBER, &d, DESCTYPE_S); -} - -static int vgetcpu_online(unsigned int cpu) -{ - return smp_call_function_single(cpu, vgetcpu_cpu_init, NULL, 1); -} static int __init init_vdso(void) { @@ -370,9 +341,7 @@ static int __init init_vdso(void) init_vdso_image(&vdso_image_x32); #endif - /* notifier priority > KVM */ - return cpuhp_setup_state(CPUHP_AP_X86_VDSO_VMA_ONLINE, - "x86/vdso/vma:online", vgetcpu_online, NULL); + return 0; } subsys_initcall(init_vdso); #endif /* CONFIG_X86_64 */ diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 44c4ef3d989b..a148d18a1ef0 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1669,6 +1669,29 @@ static void wait_for_master_cpu(int cpu) #endif } +#ifdef CONFIG_X86_64 +static void setup_getcpu(int cpu) +{ + unsigned long cpudata = vdso_encode_cpu_node(cpu, early_cpu_to_node(cpu)); + struct desc_struct d = { }; + + if (static_cpu_has(X86_FEATURE_RDTSCP)) + write_rdtscp_aux(cpudata); + + /* Store CPU and node number in limit. */ + d.limit0 = cpudata; + d.limit1 = cpudata >> 16; + + d.type = 5; /* RO data, expand down, accessed */ + d.dpl = 3; /* Visible to user code */ + d.s = 1; /* Not a system segment */ + d.p = 1; /* Present */ + d.d = 1; /* 32-bit */ + + write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_CPU_NUMBER, &d, DESCTYPE_S); +} +#endif + /* * cpu_init() initializes state that is per-CPU. Some data is already * initialized (naturally) in the bootstrap process, such as the GDT @@ -1706,6 +1729,7 @@ void cpu_init(void) early_cpu_to_node(cpu) != NUMA_NO_NODE) set_numa_node(early_cpu_to_node(cpu)); #endif + setup_getcpu(cpu); me = current;