On Wed, Jan 4, 2012 at 11:59 AM, Graeme Russ <graeme.r...@gmail.com> wrote:
> The inline assembler is ugly and uses hard coded magic numbers. Make it more
> elegant to allow cleaner implementation of future GDT related patches. The
> compiler seems smart enough to generate the same code anyway
>
> Signed-off-by: Graeme Russ <graeme.r...@gmail.com>
Acked-by: Simon Glass <s...@chromium.org>
> ---
> Changes for v2:
> - Rebased against revised patch #3
> - Use GDT size define instead of magic number
> - Added commit message
>
> arch/x86/cpu/cpu.c | 82 +++++++++++++++++++++++++++++++++------------------
> 1 files changed, 53 insertions(+), 29 deletions(-)
>
> diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
> index 209ff29..8102fb9 100644
> --- a/arch/x86/cpu/cpu.c
> +++ b/arch/x86/cpu/cpu.c
> @@ -55,35 +55,39 @@ struct gdt_ptr {
> u32 ptr;
> } __packed;
>
> -static void reload_gdt(void)
> +static void load_ds(u32 segment)
> {
> - /*
> - * There are machines which are known to not boot with the GDT
> - * being 8-byte unaligned. Intel recommends 16 byte alignment
> - */
> - static const u64 boot_gdt[] __attribute__((aligned(16))) = {
> - /* CS: code, read/execute, 4 GB, base 0 */
> - [X86_GDT_ENTRY_32BIT_CS] = GDT_ENTRY(0xc09b, 0, 0xfffff),
> - /* DS: data, read/write, 4 GB, base 0 */
> - [X86_GDT_ENTRY_32BIT_DS] = GDT_ENTRY(0xc093, 0, 0xfffff),
> - /* 16-bit CS: code, read/execute, 64 kB, base 0 */
> - [X86_GDT_ENTRY_16BIT_CS] = GDT_ENTRY(0x109b, 0, 0x0ffff),
> - /* 16-bit DS: data, read/write, 64 kB, base 0 */
> - [X86_GDT_ENTRY_16BIT_DS] = GDT_ENTRY(0x1093, 0, 0x0ffff),
> - };
> - static struct gdt_ptr gdt;
> -
> - gdt.len = sizeof(boot_gdt)-1;
> - gdt.ptr = (u32)&boot_gdt;
> -
> - asm volatile("lgdtl %0\n" \
> - "movl $((2+1)*8), %%ecx\n" \
> - "movl %%ecx, %%ds\n" \
> - "movl %%ecx, %%es\n" \
> - "movl %%ecx, %%fs\n" \
> - "movl %%ecx, %%gs\n" \
> - "movl %%ecx, %%ss" \
> - : : "m" (gdt) : "ecx");
> + asm volatile("movl %0, %%ds" : : "r" (segment * X86_GDT_ENTRY_SIZE));
> +}
> +
> +static void load_es(u32 segment)
> +{
> + asm volatile("movl %0, %%es" : : "r" (segment * X86_GDT_ENTRY_SIZE));
> +}
> +
> +static void load_fs(u32 segment)
> +{
> + asm volatile("movl %0, %%fs" : : "r" (segment * X86_GDT_ENTRY_SIZE));
> +}
> +
> +static void load_gs(u32 segment)
> +{
> + asm volatile("movl %0, %%gs" : : "r" (segment * X86_GDT_ENTRY_SIZE));
> +}
> +
> +static void load_ss(u32 segment)
> +{
> + asm volatile("movl %0, %%ss" : : "r" (segment * X86_GDT_ENTRY_SIZE));
> +}
> +
> +static void load_gdt(const u64 *boot_gdt, u16 num_entries)
> +{
> + struct gdt_ptr gdt;
> +
> + gdt.len = (num_entries * 8) - 1;
> + gdt.ptr = (u32)boot_gdt;
> +
> + asm volatile("lgdtl %0\n" : : "m" (gdt));
> }
>
> int x86_cpu_init_f(void)
> @@ -113,7 +117,27 @@ int x86_cpu_init_r(void)
> "movl %%eax, %%cr0\n"
> "wbinvd\n" : : "i" (nw_cd_rst) : "eax");
>
> - reload_gdt();
> + /*
> + * There are machines which are known to not boot with the GDT
> + * being 8-byte unaligned. Intel recommends 16 byte alignment
> + */
> + static const u64 boot_gdt[] __aligned(16) = {
> + /* CS: code, read/execute, 4 GB, base 0 */
> + [X86_GDT_ENTRY_32BIT_CS] = GDT_ENTRY(0xc09b, 0, 0xfffff),
> + /* DS: data, read/write, 4 GB, base 0 */
> + [X86_GDT_ENTRY_32BIT_DS] = GDT_ENTRY(0xc093, 0, 0xfffff),
> + /* 16-bit CS: code, read/execute, 64 kB, base 0 */
> + [X86_GDT_ENTRY_16BIT_CS] = GDT_ENTRY(0x109b, 0, 0x0ffff),
> + /* 16-bit DS: data, read/write, 64 kB, base 0 */
> + [X86_GDT_ENTRY_16BIT_DS] = GDT_ENTRY(0x1093, 0, 0x0ffff),
> + };
> +
> + load_gdt(boot_gdt, X86_GDT_NUM_ENTRIES);
> + load_ds(X86_GDT_ENTRY_32BIT_DS);
> + load_es(X86_GDT_ENTRY_32BIT_DS);
> + load_fs(X86_GDT_ENTRY_32BIT_DS);
> + load_gs(X86_GDT_ENTRY_32BIT_DS);
> + load_ss(X86_GDT_ENTRY_32BIT_DS);
>
> /* Initialize core interrupt and exception functionality of CPU */
> cpu_init_interrupts();
> --
> 1.7.5.2.317.g391b14
>
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