[tip:x86/urgent] x86, gdt, hibernate: Store/load GDT for hibernate path.

From: tip-bot for Konrad Rzeszutek Wilk
Date: Thu May 02 2013 - 13:25:25 EST

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Commit-ID: 6e060be60bca76941481fb956a9b6d30065189ad
Gitweb: http://git.kernel.org/tip/6e060be60bca76941481fb956a9b6d30065189ad
Author: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
AuthorDate: Wed, 1 May 2013 21:53:30 -0400
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Thu, 2 May 2013 10:16:24 -0700

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@xxxxxxxxx>
Acked-by: "Rafael J. Wysocki" <rjw@xxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1367459610-9656-2-git-send-email-konrad.wilk@xxxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/suspend_32.h | 1 +
arch/x86/include/asm/suspend_64.h | 2 ++
arch/x86/kernel/asm-offsets_32.c | 3 +++
arch/x86/kernel/asm-offsets_64.c | 1 +
arch/x86/power/cpu.c | 15 ++++++++++-----
arch/x86/power/hibernate_asm_32.S | 4 ++++
arch/x86/power/hibernate_asm_64.S | 3 +++
7 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/suspend_32.h b/arch/x86/include/asm/suspend_32.h
index f6064b7..552d6c9 100644
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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 */
--
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Next message: Tejun Heo: "Re: [PATCH 15/31] blk-throttle: reorganize throtl_service_queuepassed around as argument"
Previous message: tip-bot for Borislav Petkov: "[tip:x86/urgent] x86/kconfig: Add a Kconfig shortcut for building working KVM guest kernels"
In reply to: Konrad Rzeszutek Wilk: "Re: [PATCH] x86, x86-64, gdt, hibernate: Store/load GDT forhibernate path."
Next in thread: tip-bot for Konrad Rzeszutek Wilk: "[tip:x86/urgent] x86, gdt, hibernate: Store/load GDT for hibernate path."
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