[PATCH 1/3] x86,vdso: Change the PER_CPU segment to use struct desc_struct

2014-07-25 Thread Andy Lutomirski 
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 
---
 arch/x86/kernel/vsyscall_64.c | 18 +++---
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index e1e1e80..158cdff 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -289,7 +289,7 @@ sigsegv:
  */
 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);
@@ -298,13 +298,17 @@ 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 = 0x0f400ULL;
-   d |= cpu;
-   d |= (node & 0xf) << 12;
-   d |= (node >> 4) << 48;
+   memset(, 0, sizeof(d));
+   d.limit0 = cpu | ((node & 0xf) << 12);
+   d.limit = node >> 4;
+   d.type = 4; /* RO data, expand down */
+   d.dpl = 3;  /* Visible to user code */
+   d.s = 1;/* Non a system segment */
+   d.p = 1;/* Present */
 
write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, , 
DESCTYPE_S);
 }
-- 
1.9.3

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[PATCH 1/3] x86,vdso: Change the PER_CPU segment to use struct desc_struct

2014-07-25 Thread Andy Lutomirski 
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 l...@amacapital.net
---
 arch/x86/kernel/vsyscall_64.c | 18 +++---
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index e1e1e80..158cdff 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -289,7 +289,7 @@ sigsegv:
  */
 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);
@@ -298,13 +298,17 @@ 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 = 0x0f400ULL;
-   d |= cpu;
-   d |= (node  0xf)  12;
-   d |= (node  4)  48;
+   memset(d, 0, sizeof(d));
+   d.limit0 = cpu | ((node  0xf)  12);
+   d.limit = node  4;
+   d.type = 4; /* RO data, expand down */
+   d.dpl = 3;  /* Visible to user code */
+   d.s = 1;/* Non a system segment */
+   d.p = 1;/* Present */
 
write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, d, 
DESCTYPE_S);
 }
-- 
1.9.3

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