Messages in this thread Patch in this message | | | From | Andy Lutomirski <> | Subject | [PATCH 1/3] x86,vdso: Change the PER_CPU segment to use struct desc_struct | Date | Fri, 25 Jul 2014 18:12:59 -0700 |
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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@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 = 0x0f40000000000ULL; - 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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