The current K8 stack preservation code in disable_car() works by chance,
but that's not something we should rely on.
The new code is entirely rewritten, fixes a few missing constraints in
the asm and should be a lot more readable. However, the generated code
should be mostly identical.
Attached for Ron.
Signed-off-by: Carl-Daniel Hailfinger <[EMAIL PROTECTED]>
Index: corebootv3-k8_car_disable_inline_asm/arch/x86/amd/k8/stage1.c
===================================================================
--- corebootv3-k8_car_disable_inline_asm/arch/x86/amd/k8/stage1.c
(Revision 856)
+++ corebootv3-k8_car_disable_inline_asm/arch/x86/amd/k8/stage1.c
(Arbeitskopie)
@@ -34,20 +34,31 @@
*/
void disable_car(void)
{
- /* OK, here is the theory: we should be able to copy
- * the data back over itself, and the wbinvd should then
- * flush to memory. Let's see.
- */
- /* nope.
- __asm__ __volatile__("cld; rep movsl" ::"D" (CONFIG_CARBASE), "S"
(CONFIG_CARBASE), "c" (CONFIG_CARSIZE/4): "memory");
- */
/* call the inlined function */
disable_cache_as_ram();
- /* copy it down, wbinvd, copy it back? */
- __asm__ __volatile__("cld; rep movsl" ::"D" (0x88000), "S"
(CONFIG_CARBASE), "c" (CONFIG_CARSIZE/4): "memory");
- __asm__ __volatile__ ("wbinvd\n");
- __asm__ __volatile__("cld; rep movsl" ::"D" (CONFIG_CARBASE), "S"
(0x88000), "c" (CONFIG_CARSIZE/4): "memory");
+ /* The BKDG says that a WBINVD will not flush CAR to RAM (because the
+ * cache tags are not dirty).
+ * Solution:
+ * - Two subsequent memcpy in the same inline asm block, one from stack
+ * to backup, one from backup to stack.
+ * The solution for geode of using a inline asm memcpy of the stack
+ * onto itself will not mark the cache tags as dirty on K8.
+ */
+ __asm__ __volatile__(
+ " movl %[carbase], %%esi \n"
+ " movl %[backuplocation], %%edi \n"
+ " movl %[carsizequads], %%ecx \n"
+ " cld \n"
+ " rep movsl \n"
+ " wbinvd \n"
+ " movl %[backuplocation], %%esi \n"
+ " movl %[carbase], %%edi \n"
+ " movl %[carsizequads], %%ecx \n"
+ " rep movsl \n"
+ :: [carbase] "i" (CONFIG_CARBASE), [backuplocation] "i" (0x88000),
+ [carsizequads] "i" (CONFIG_CARSIZE/4)
+ : "memory", "%edi", "%esi", "%ecx");
banner(BIOS_DEBUG, "Disable_car: done wbinvd");
banner(BIOS_DEBUG, "disable_car: done");
}
--
http://www.hailfinger.org/
Index: corebootv3-k8_car_disable_inline_asm/arch/x86/amd/k8/stage1.c
===================================================================
--- corebootv3-k8_car_disable_inline_asm/arch/x86/amd/k8/stage1.c (Revision 856)
+++ corebootv3-k8_car_disable_inline_asm/arch/x86/amd/k8/stage1.c (Arbeitskopie)
@@ -34,20 +34,31 @@
*/
void disable_car(void)
{
- /* OK, here is the theory: we should be able to copy
- * the data back over itself, and the wbinvd should then
- * flush to memory. Let's see.
- */
- /* nope.
- __asm__ __volatile__("cld; rep movsl" ::"D" (CONFIG_CARBASE), "S" (CONFIG_CARBASE), "c" (CONFIG_CARSIZE/4): "memory");
- */
/* call the inlined function */
disable_cache_as_ram();
- /* copy it down, wbinvd, copy it back? */
- __asm__ __volatile__("cld; rep movsl" ::"D" (0x88000), "S" (CONFIG_CARBASE), "c" (CONFIG_CARSIZE/4): "memory");
- __asm__ __volatile__ ("wbinvd\n");
- __asm__ __volatile__("cld; rep movsl" ::"D" (CONFIG_CARBASE), "S" (0x88000), "c" (CONFIG_CARSIZE/4): "memory");
+ /* The BKDG says that a WBINVD will not flush CAR to RAM (because the
+ * cache tags are not dirty).
+ * Solution:
+ * - Two subsequent memcpy in the same inline asm block, one from stack
+ * to backup, one from backup to stack.
+ * The solution for geode of using a inline asm memcpy of the stack
+ * onto itself will not mark the cache tags as dirty on K8.
+ */
+ __asm__ __volatile__(
+ " movl %[carbase], %%esi \n"
+ " movl %[backuplocation], %%edi \n"
+ " movl %[carsizequads], %%ecx \n"
+ " cld \n"
+ " rep movsl \n"
+ " wbinvd \n"
+ " movl %[backuplocation], %%esi \n"
+ " movl %[carbase], %%edi \n"
+ " movl %[carsizequads], %%ecx \n"
+ " rep movsl \n"
+ :: [carbase] "i" (CONFIG_CARBASE), [backuplocation] "i" (0x88000),
+ [carsizequads] "i" (CONFIG_CARSIZE/4)
+ : "memory", "%edi", "%esi", "%ecx");
banner(BIOS_DEBUG, "Disable_car: done wbinvd");
banner(BIOS_DEBUG, "disable_car: done");
}
--
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