x86, gdt, hibernate: Store/load GDT for hibernate path.

The git commite7a5cd063c7b4c58417f674821d63f5eb6747e37
("x86-64, gdt: Store/load GDT for ACPI S3 or hibernate/resume path
is not needed.") assumes that for the hibernate path the booting
kernel and the resuming kernel MUST be the same. That is certainly
the case for a 32-bit kernel (see check_image_kernel and
CONFIG_ARCH_HIBERNATION_HEADER config option).

However for 64-bit kernels it is OK to have a different kernel
version (and size of the image) of the booting and resuming kernels.
Hence the above mentioned git commit introduces an regression.

This patch fixes it by introducing a 'struct desc_ptr gdt_desc'
back in the 'struct saved_context'. However instead of having in the
'save_processor_state' and 'restore_processor_state' the
store/load_gdt calls, we are only saving the GDT in the
save_processor_state.

For the restore path the lgdt operation is done in
hibernate_asm_[32|64].S in the 'restore_registers' path.

The apt reader of this description will recognize that only 64-bit
kernels need this treatment, not 32-bit. This patch adds the logic
in the 32-bit path to be more similar to 64-bit so that in the future
the unification process can take advantage of this.

[ hpa: this also reverts an inadvertent on-disk format change ]

Suggested-by: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/1367459610-9656-2-git-send-email-konrad.wilk@oracle.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/suspend_32.h b/arch/x86/include/asm/suspend_32.h
index f6064b7..552d6c9 100644 (file)
--- a/arch/x86/include/asm/suspend_32.h
+++ b/arch/x86/include/asm/suspend_32.h
@@ -15,6 +15,7 @@ struct saved_context {
        unsigned long cr0, cr2, cr3, cr4;
        u64 misc_enable;
        bool misc_enable_saved;
+       struct desc_ptr gdt_desc;
        struct desc_ptr idt;
        u16 ldt;
        u16 tss;

diff --git a/arch/x86/include/asm/suspend_64.h b/arch/x86/include/asm/suspend_64.h
index 97b84e0..bc62328 100644 (file)
--- a/arch/x86/include/asm/suspend_64.h
+++ b/arch/x86/include/asm/suspend_64.h
@@ -25,6 +25,8 @@ struct saved_context {
        u64 misc_enable;
        bool misc_enable_saved;
        unsigned long efer;
+       u16 gdt_pad; /* Unused */
+       struct desc_ptr gdt_desc;
        u16 idt_pad;
        u16 idt_limit;
        unsigned long idt_base;

diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index 85d98ab..0ef4bba 100644 (file)
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -60,6 +60,9 @@ void foo(void)
        OFFSET(IA32_RT_SIGFRAME_sigcontext, rt_sigframe, uc.uc_mcontext);
        BLANK();
 
+       OFFSET(saved_context_gdt_desc, saved_context, gdt_desc);
+       BLANK();
+
        /* Offset from the sysenter stack to tss.sp0 */
        DEFINE(TSS_sysenter_sp0, offsetof(struct tss_struct, x86_tss.sp0) -
                 sizeof(struct tss_struct));

diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index 1b4754f..e7c798b 100644 (file)
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -73,6 +73,7 @@ int main(void)
        ENTRY(cr3);
        ENTRY(cr4);
        ENTRY(cr8);
+       ENTRY(gdt_desc);
        BLANK();
 #undef ENTRY
 

diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 6d6e907..1cf5b30 100644 (file)
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -25,16 +25,12 @@
 #include <asm/cpu.h>
 
 #ifdef CONFIG_X86_32
-static struct saved_context saved_context;
-
 unsigned long saved_context_ebx;
 unsigned long saved_context_esp, saved_context_ebp;
 unsigned long saved_context_esi, saved_context_edi;
 unsigned long saved_context_eflags;
-#else
-/* CONFIG_X86_64 */
-struct saved_context saved_context;
 #endif
+struct saved_context saved_context;
 
 /**
  *     __save_processor_state - save CPU registers before creating a
@@ -67,6 +63,15 @@ static void __save_processor_state(struct saved_context *ctxt)
 /* CONFIG_X86_64 */
        store_idt((struct desc_ptr *)&ctxt->idt_limit);
 #endif
+       /*
+        * We save it here, but restore it only in the hibernate case.
+        * For ACPI S3 resume, this is loaded via 'early_gdt_desc' in 64-bit
+        * mode in "secondary_startup_64". In 32-bit mode it is done via
+        * 'pmode_gdt' in wakeup_start.
+        */
+       ctxt->gdt_desc.size = GDT_SIZE - 1;
+       ctxt->gdt_desc.address = (unsigned long)get_cpu_gdt_table(smp_processor_id());
+
        store_tr(ctxt->tr);
 
        /* XMM0..XMM15 should be handled by kernel_fpu_begin(). */

diff --git a/arch/x86/power/hibernate_asm_32.S b/arch/x86/power/hibernate_asm_32.S
index ad47dae..1d0fa0e 100644 (file)
--- a/arch/x86/power/hibernate_asm_32.S
+++ b/arch/x86/power/hibernate_asm_32.S
@@ -75,6 +75,10 @@ done:
        pushl saved_context_eflags
        popfl
 
+       /* Saved in save_processor_state. */
+       movl $saved_context, %eax
+       lgdt saved_context_gdt_desc(%eax)
+
        xorl    %eax, %eax
 
        ret

diff --git a/arch/x86/power/hibernate_asm_64.S b/arch/x86/power/hibernate_asm_64.S
index 9356547..3c4469a 100644 (file)
--- a/arch/x86/power/hibernate_asm_64.S
+++ b/arch/x86/power/hibernate_asm_64.S
@@ -139,6 +139,9 @@ ENTRY(restore_registers)
        pushq   pt_regs_flags(%rax)
        popfq
 
+       /* Saved in save_processor_state. */
+       lgdt    saved_context_gdt_desc(%rax)
+
        xorq    %rax, %rax
 
        /* tell the hibernation core that we've just restored the memory */