lkml.org 
[lkml]   [2018]   [Oct]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:x86/asm] x86/vdso: Initialize the CPU/node NR segment descriptor earlier
Commit-ID:  b2e2ba578e016a091eb31565849990fe68c7c599
Gitweb: https://git.kernel.org/tip/b2e2ba578e016a091eb31565849990fe68c7c599
Author: Chang S. Bae <chang.seok.bae@intel.com>
AuthorDate: Tue, 18 Sep 2018 16:08:59 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 8 Oct 2018 10:41:10 +0200

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>
---
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;

\
 
 \ /
  Last update: 2018-10-08 12:00    [W:0.128 / U:5.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site