Commit-ID: 258801563ba1be05793f2417ae30557b43a24e4e
Gitweb: http://git.kernel.org/tip/258801563ba1be05793f2417ae30557b43a24e4e
Author: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
AuthorDate: Tue, 23 Sep 2014 10:50:53 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 28 Oct 2014 11:22:10 +0100
x86/vdso: Change the PER_CPU segment to use struct desc_struct
This makes it easier to see what's going on. It produces
exactly the same segment descriptor as the old code.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/d492f7b55136cbc60f016adae79160707b2e03b7.1411494540.git.luto@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/vdso/vma.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index a155dca..261b134 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -248,7 +248,7 @@ __setup("vdso=", vdso_setup);
*/
static void vsyscall_set_cpu(int cpu)
{
- unsigned long d;
+ struct desc_struct d;
unsigned long node = 0;
#ifdef CONFIG_NUMA
node = cpu_to_node(cpu);
@@ -257,13 +257,18 @@ static void vsyscall_set_cpu(int cpu)
write_rdtscp_aux((node << 12) | cpu);
/*
- * Store cpu number in limit so that it can be loaded quickly
- * in user space in vgetcpu. (12 bits for the CPU and 8 bits for the node)
+ * Store cpu number in limit so that it can be loaded
+ * quickly in user space in vgetcpu. (12 bits for the CPU
+ * and 8 bits for the node)
*/
- d = 0x0f40000000000ULL;
- d |= cpu;
- d |= (node & 0xf) << 12;
- d |= (node >> 4) << 48;
+ d = (struct desc_struct) {
+ .limit0 = cpu | ((node & 0xf) << 12),
+ .limit = node >> 4,
+ .type = 4, /* RO data, expand down */
+ .dpl = 3, /* Visible to user code */
+ .s = 1, /* Not a system segment */
+ .p = 1, /* Present */
+ };
write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
}
--
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