linux-kernel - Re: [RFC] merge 32/64 bits realmode wakeup code

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Date:	Thu, 27 Jan 2011 23:53:59 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	matthieu castet <castet.matthieu@...e.fr>
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>,
	linux-acpi@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org
Subject: Re: [RFC] merge 32/64 bits realmode wakeup code

On Thursday, January 27, 2011, matthieu castet wrote:
> Hi,
> 
> this patch merge 32 and 64 realmode wakeup code :
> - this mean less ifdef in code
> - we could remove now unused field in wakeup_header (pmode_*)
> - this allow to set the first 1 MB NX.
> 
> Do you think it is safe on all X86 32 bit machine ?
> 
> Matthieu
> 
> 
> Signed-off-by: Matthieu CASTET <castet.matthieu@...e.fr>

It _looks_ sane, but it will require some serious testing.  I'm not sure,
though, if we can get enough testing coverage without actually committing
that change.

How much testing has it received so far?

[Patch appended below for the convenience of future reviewers.  Really,
 please don't attach patches if you want people to comment them.  That's
 a major inconvenience.  Please put them into the message body instead.]

Rafael


---
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3ed5ad9..3baa11c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -219,7 +219,7 @@ config X86_HT
 
 config X86_TRAMPOLINE
 	def_bool y
-	depends on SMP || (64BIT && ACPI_SLEEP)
+	depends on SMP || ACPI_SLEEP
 
 config X86_32_LAZY_GS
 	def_bool y
diff --git a/arch/x86/kernel/acpi/realmode/wakeup.S b/arch/x86/kernel/acpi/realmode/wakeup.S
index 28595d6..2c2d5b8 100644
--- a/arch/x86/kernel/acpi/realmode/wakeup.S
+++ b/arch/x86/kernel/acpi/realmode/wakeup.S
@@ -90,36 +90,10 @@ _start:
 
 	/* Do any other stuff... */
 
-#ifndef CONFIG_64BIT
-	/* This could also be done in C code... */
-	movl	pmode_cr3, %eax
-	movl	%eax, %cr3
-
-	movl	pmode_cr4, %ecx
-	jecxz	1f
-	movl	%ecx, %cr4
-1:
-	movl	pmode_efer, %eax
-	movl	pmode_efer + 4, %edx
-	movl	%eax, %ecx
-	orl	%edx, %ecx
-	jz	1f
-	movl	$MSR_EFER, %ecx
-	wrmsr
-1:
-
-	lgdtl	pmode_gdt
-
-	/* This really couldn't... */
-	movl	pmode_cr0, %eax
-	movl	%eax, %cr0
-	jmp	pmode_return
-#else
 	pushw	$0
 	pushw	trampoline_segment
 	pushw	$0
 	lret
-#endif
 
 bogus_real_magic:
 1:
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 69fd72a..d32bef9 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -26,7 +26,7 @@ unsigned long acpi_realmode_flags;
 /* address in low memory of the wakeup routine. */
 static unsigned long acpi_realmode;
 
-#if defined(CONFIG_SMP) && defined(CONFIG_64BIT)
+#if defined(CONFIG_SMP)
 static char temp_stack[4096];
 #endif
 
@@ -80,31 +80,24 @@ int acpi_save_state_mem(void)
 	header->wakeup_gdt[2] =
 		GDT_ENTRY(0x8093, acpi_wakeup_address, 0xfffff);
 
-#ifndef CONFIG_64BIT
-	store_gdt((struct desc_ptr *)&header->pmode_gdt);
-
-	if (rdmsr_safe(MSR_EFER, &header->pmode_efer_low,
-		       &header->pmode_efer_high))
-		header->pmode_efer_low = header->pmode_efer_high = 0;
-#endif /* !CONFIG_64BIT */
-
 	header->pmode_cr0 = read_cr0();
 	header->pmode_cr4 = read_cr4_safe();
 	header->realmode_flags = acpi_realmode_flags;
 	header->real_magic = 0x12345678;
-
-#ifndef CONFIG_64BIT
-	header->pmode_entry = (u32)&wakeup_pmode_return;
-	header->pmode_cr3 = (u32)__pa(&initial_page_table);
-	saved_magic = 0x12345678;
-#else /* CONFIG_64BIT */
 	header->trampoline_segment = setup_trampoline() >> 4;
 #ifdef CONFIG_SMP
 	stack_start.sp = temp_stack + sizeof(temp_stack);
 	early_gdt_descr.address =
 			(unsigned long)get_cpu_gdt_table(smp_processor_id());
+#ifdef CONFIG_64BIT
 	initial_gs = per_cpu_offset(smp_processor_id());
 #endif
+#endif
+
+#ifndef CONFIG_64BIT
+	initial_code = (unsigned long)&wakeup_pmode_return;
+	saved_magic = 0x12345678;
+#else
 	initial_code = (unsigned long)wakeup_long64;
        saved_magic = 0x123456789abcdef0L;
 #endif /* CONFIG_64BIT */
diff --git a/arch/x86/kernel/trampoline_32.S b/arch/x86/kernel/trampoline_32.S
index 8508237..11f0387 100644
--- a/arch/x86/kernel/trampoline_32.S
+++ b/arch/x86/kernel/trampoline_32.S
@@ -32,8 +32,12 @@
 #include <asm/segment.h>
 #include <asm/page_types.h>
 
-/* We can free up trampoline after bootup if cpu hotplug is not supported. */
+#ifdef CONFIG_ACPI_SLEEP
+.section .rodata, "a", @progbits
+#else
+/* We can free up the trampoline after bootup if cpu hotplug is not supported. */
 __CPUINITRODATA
+#endif
 .code16
 
 ENTRY(trampoline_data)
--
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