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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 <hpa@zytor.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1537312139-5580-9-git-send-email-chang.seok.bae@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Chang S. Bae 2018-09-18 16:08:59 -07:00 committed by Ingo Molnar
parent ffebbaedc8
commit b2e2ba578e
2 changed files with 25 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
arch/x86/entry/vdso/vma.c
View File

@ -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 */

24
arch/x86/kernel/cpu/common.c
View File

@ -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;