[RFC] x86: Unify allocation of low memory trampolines

[RFC] x86: Unify allocation of low memory trampolines

[H. Peter Anvin]

This patchset unifies all the allocation of low memory (a.k.a. realmode
memory, low megabyte) code (currently there are three users of low
memory: BIOS reboot, suspend, and of course the SMP trampoline -- there
is at least one additional one coming down the pipe in the near term)
and reserves and installs them as a single memory object very early
during initialization.  This means the original can be put in initrodata
and discarded after the allocation is done.

I consider this patchset to be a first step: the next step is to
actually link all the realmode code together into a single common
address space before encapsulation.  This will enable X/W separation as
well as provide an even more natural way to access symbols in the real
mode object.

	-hpa

[tip:x86/trampoline] x86, trampoline: Common infrastructure for low memory trampolines

[tip-bot for H. Peter Anvin]

Commit-ID:  4822b7fc6d4870685a9feadfc348d48f5e47460a
Gitweb:     http://git.kernel.org/tip/4822b7fc6d4870685a9feadfc348d48f5e47460a
Author:     H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Mon, 14 Feb 2011 15:34:57 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 17 Feb 2011 21:02:43 -0800

x86, trampoline: Common infrastructure for low memory trampolines

Common infrastructure for low memory trampolines.  This code installs
the trampolines permanently in low memory very early.  It also permits
multiple pieces of code to be used for this purpose.

This code also introduces a standard infrastructure for computing
symbol addresses in the trampoline code.

The only change to the actual SMP trampolines themselves is that the
64-bit trampoline has been made reusable -- the previous version would
overwrite the code with a status variable; this moves the status
variable to a separate location.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4D5DFBE4.7090104@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
---
 arch/x86/Kconfig                |    4 ---
 arch/x86/kernel/Makefile        |    3 +-
 arch/x86/kernel/head32.c        |    9 --------
 arch/x86/kernel/head_64.S       |    3 +-
 arch/x86/kernel/setup.c         |    2 +-
 arch/x86/kernel/smpboot.c       |   10 +++++---
 arch/x86/kernel/trampoline.c    |   42 ++++++++++++++++++++------------------
 arch/x86/kernel/trampoline_32.S |   15 ++++++++++---
 arch/x86/kernel/trampoline_64.S |   30 ++++++++++++++++-----------
 arch/x86/kernel/vmlinux.lds.S   |   13 ++++++++++++
 10 files changed, 73 insertions(+), 58 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d5ed94d..1359bc9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -217,10 +217,6 @@ config X86_HT
 	def_bool y
 	depends on SMP
 
-config X86_TRAMPOLINE
-	def_bool y
-	depends on SMP || (64BIT && ACPI_SLEEP)
-
 config X86_32_LAZY_GS
 	def_bool y
 	depends on X86_32 && !CC_STACKPROTECTOR
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 34244b2..2e8ce0d 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -47,7 +47,7 @@ obj-y			+= tsc.o io_delay.o rtc.o
 obj-y			+= pci-iommu_table.o
 obj-y			+= resource.o
 
-obj-$(CONFIG_X86_TRAMPOLINE)	+= trampoline.o
+obj-y				+= trampoline.o trampoline_$(BITS).o
 obj-y				+= process.o
 obj-y				+= i387.o xsave.o
 obj-y				+= ptrace.o
@@ -69,7 +69,6 @@ obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_SMP)		+= smpboot.o tsc_sync.o
 obj-$(CONFIG_SMP)		+= setup_percpu.o
 obj-$(CONFIG_X86_64_SMP)	+= tsc_sync.o
-obj-$(CONFIG_X86_TRAMPOLINE)	+= trampoline_$(BITS).o
 obj-$(CONFIG_X86_MPPARSE)	+= mpparse.o
 obj-y				+= apic/
 obj-$(CONFIG_X86_REBOOTFIXUPS)	+= reboot_fixups_32.o
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 7f138b3..d6d6bb3 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -34,15 +34,6 @@ void __init i386_start_kernel(void)
 {
 	memblock_init();
 
-#ifdef CONFIG_X86_TRAMPOLINE
-	/*
-	 * But first pinch a few for the stack/trampoline stuff
-	 * FIXME: Don't need the extra page at 4K, but need to fix
-	 * trampoline before removing it. (see the GDT stuff)
-	 */
-	memblock_x86_reserve_range(PAGE_SIZE, PAGE_SIZE + PAGE_SIZE, "EX TRAMPOLINE");
-#endif
-
 	memblock_x86_reserve_range(__pa_symbol(&_text), __pa_symbol(&__bss_stop), "TEXT DATA BSS");
 
 #ifdef CONFIG_BLK_DEV_INITRD
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 239046b..e11e394 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -136,10 +136,9 @@ ident_complete:
 	/* Fixup phys_base */
 	addq	%rbp, phys_base(%rip)
 
-#ifdef CONFIG_X86_TRAMPOLINE
+	/* Fixup trampoline */
 	addq	%rbp, trampoline_level4_pgt + 0(%rip)
 	addq	%rbp, trampoline_level4_pgt + (511*8)(%rip)
-#endif
 
 	/* Due to ENTRY(), sometimes the empty space gets filled with
 	 * zeros. Better take a jmp than relying on empty space being
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d3cfe26..994ea20 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -935,7 +935,7 @@ void __init setup_arch(char **cmdline_p)
 	printk(KERN_DEBUG "initial memory mapped : 0 - %08lx\n",
 			max_pfn_mapped<<PAGE_SHIFT);
 
-	reserve_trampoline_memory();
+	setup_trampolines();
 
 #ifdef CONFIG_ACPI_SLEEP
 	/*
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 08776a9..5452733 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -788,7 +788,7 @@ do_rest:
 	stack_start  = c_idle.idle->thread.sp;
 
 	/* start_ip had better be page-aligned! */
-	start_ip = setup_trampoline();
+	start_ip = trampoline_address();
 
 	/* So we see what's up */
 	announce_cpu(cpu, apicid);
@@ -798,6 +798,8 @@ do_rest:
 	 * the targeted processor.
 	 */
 
+	printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
+
 	atomic_set(&init_deasserted, 0);
 
 	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
@@ -851,8 +853,8 @@ do_rest:
 			pr_debug("CPU%d: has booted.\n", cpu);
 		else {
 			boot_error = 1;
-			if (*((volatile unsigned char *)trampoline_base)
-					== 0xA5)
+			if (*(volatile u32 *)TRAMPOLINE_SYM(trampoline_status)
+			    == 0xA5A5A5A5)
 				/* trampoline started but...? */
 				pr_err("CPU%d: Stuck ??\n", cpu);
 			else
@@ -878,7 +880,7 @@ do_rest:
 	}
 
 	/* mark "stuck" area as not stuck */
-	*((volatile unsigned long *)trampoline_base) = 0;
+	*(volatile u32 *)TRAMPOLINE_SYM(trampoline_status) = 0;
 
 	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
 		/*
diff --git a/arch/x86/kernel/trampoline.c b/arch/x86/kernel/trampoline.c
index a375616..a91ae77 100644
--- a/arch/x86/kernel/trampoline.c
+++ b/arch/x86/kernel/trampoline.c
@@ -2,39 +2,41 @@
 #include <linux/memblock.h>
 
 #include <asm/trampoline.h>
+#include <asm/cacheflush.h>
 #include <asm/pgtable.h>
 
-#if defined(CONFIG_X86_64) && defined(CONFIG_ACPI_SLEEP)
-#define __trampinit
-#define __trampinitdata
-#else
-#define __trampinit __cpuinit
-#define __trampinitdata __cpuinitdata
-#endif
+unsigned char *x86_trampoline_base;
 
-/* ready for x86_64 and x86 */
-unsigned char *__trampinitdata trampoline_base;
-
-void __init reserve_trampoline_memory(void)
+void __init setup_trampolines(void)
 {
 	phys_addr_t mem;
+	size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
 
 	/* Has to be in very low memory so we can execute real-mode AP code. */
-	mem = memblock_find_in_range(0, 1<<20, TRAMPOLINE_SIZE, PAGE_SIZE);
+	mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
 	if (mem == MEMBLOCK_ERROR)
 		panic("Cannot allocate trampoline\n");
 
-	trampoline_base = __va(mem);
-	memblock_x86_reserve_range(mem, mem + TRAMPOLINE_SIZE, "TRAMPOLINE");
+	x86_trampoline_base = __va(mem);
+	memblock_x86_reserve_range(mem, mem + size, "TRAMPOLINE");
+
+	printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
+	       x86_trampoline_base, (unsigned long long)mem, size);
+
+	memcpy(x86_trampoline_base, x86_trampoline_start, size);
 }
 
 /*
- * Currently trivial. Write the real->protected mode
- * bootstrap into the page concerned. The caller
- * has made sure it's suitably aligned.
+ * setup_trampolines() gets called very early, to guarantee the
+ * availability of low memory.  This is before the proper kernel page
+ * tables are set up, so we cannot set page permissions in that
+ * function.  Thus, we use an arch_initcall instead.
  */
-unsigned long __trampinit setup_trampoline(void)
+static int __init configure_trampolines(void)
 {
-	memcpy(trampoline_base, trampoline_data, TRAMPOLINE_SIZE);
-	return virt_to_phys(trampoline_base);
+	size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
+
+	set_memory_x((unsigned long)x86_trampoline_base, size >> PAGE_SHIFT);
+	return 0;
 }
+arch_initcall(configure_trampolines);
diff --git a/arch/x86/kernel/trampoline_32.S b/arch/x86/kernel/trampoline_32.S
index 8508237..451c0a7 100644
--- a/arch/x86/kernel/trampoline_32.S
+++ b/arch/x86/kernel/trampoline_32.S
@@ -32,9 +32,11 @@
 #include <asm/segment.h>
 #include <asm/page_types.h>
 
-/* We can free up trampoline after bootup if cpu hotplug is not supported. */
-__CPUINITRODATA
-.code16
+#ifdef CONFIG_SMP
+
+	.section ".x86_trampoline","a"
+	.balign PAGE_SIZE
+	.code16
 
 ENTRY(trampoline_data)
 r_base = .
@@ -44,7 +46,7 @@ r_base = .
 
 	cli			# We should be safe anyway
 
-	movl	$0xA5A5A5A5, trampoline_data - r_base
+	movl	$0xA5A5A5A5, trampoline_status - r_base
 				# write marker for master knows we're running
 
 	/* GDT tables in non default location kernel can be beyond 16MB and
@@ -72,5 +74,10 @@ boot_idt_descr:
 	.word	0				# idt limit = 0
 	.long	0				# idt base = 0L
 
+ENTRY(trampoline_status)
+	.long	0
+
 .globl trampoline_end
 trampoline_end:
+
+#endif /* CONFIG_SMP */
diff --git a/arch/x86/kernel/trampoline_64.S b/arch/x86/kernel/trampoline_64.S
index 075d130..49c77a6 100644
--- a/arch/x86/kernel/trampoline_64.S
+++ b/arch/x86/kernel/trampoline_64.S
@@ -32,13 +32,9 @@
 #include <asm/segment.h>
 #include <asm/processor-flags.h>
 
-#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
+	.section ".x86_trampoline","a"
+	.balign PAGE_SIZE
+	.code16
 
 ENTRY(trampoline_data)
 r_base = .
@@ -50,7 +46,7 @@ r_base = .
 	mov	%ax, %ss
 
 
-	movl	$0xA5A5A5A5, trampoline_data - r_base
+	movl	$0xA5A5A5A5, trampoline_status - r_base
 				# write marker for master knows we're running
 
 					# Setup stack
@@ -64,10 +60,13 @@ r_base = .
 	movzx	%ax, %esi		# Find the 32bit trampoline location
 	shll	$4, %esi
 
-					# Fixup the vectors
-	addl	%esi, startup_32_vector - r_base
-	addl	%esi, startup_64_vector - r_base
-	addl	%esi, tgdt + 2 - r_base	# Fixup the gdt pointer
+					# Fixup the absolute vectors
+	leal	(startup_32 - r_base)(%esi), %eax
+	movl	%eax, startup_32_vector - r_base
+	leal	(startup_64 - r_base)(%esi), %eax
+	movl	%eax, startup_64_vector - r_base
+	leal	(tgdt - r_base)(%esi), %eax
+	movl	%eax, (tgdt + 2 - r_base)
 
 	/*
 	 * GDT tables in non default location kernel can be beyond 16MB and
@@ -129,6 +128,7 @@ no_longmode:
 	jmp no_longmode
 #include "verify_cpu.S"
 
+	.balign 4
 	# Careful these need to be in the same 64K segment as the above;
 tidt:
 	.word	0			# idt limit = 0
@@ -156,6 +156,12 @@ startup_64_vector:
 	.long	startup_64 - r_base
 	.word	__KERNEL_CS, 0
 
+	.balign 4
+fixup_base:
+	.long	0
+ENTRY(trampoline_status)
+	.long	0
+
 trampoline_stack:
 	.org 0x1000
 trampoline_stack_end:
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index bf47007..cb2c506 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -240,6 +240,18 @@ SECTIONS
 
 	INIT_DATA_SECTION(16)
 
+	/*
+	 * Code and data for a variety of lowlevel trampolines, to be
+	 * copied into base memory (< 1 MiB) during initialization.
+	 * Since it is copied early, the main copy can be discarded
+	 * afterwards.
+	 */
+	 .x86_trampoline : AT(ADDR(.x86_trampoline) - LOAD_OFFSET) {
+		x86_trampoline_start = .;
+		*(.x86_trampoline)
+		x86_trampoline_end = .;
+	}
+
 	.x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) {
 		__x86_cpu_dev_start = .;
 		*(.x86_cpu_dev.init)
@@ -291,6 +303,7 @@ SECTIONS
 		*(.iommu_table)
 		__iommu_table_end = .;
 	}
+
 	. = ALIGN(8);
 	/*
 	 * .exit.text is discard at runtime, not link time, to deal with

Re: [tip:x86/trampoline] x86, trampoline: Common infrastructure for low memory trampolines

[Brian Gerst]

On Fri, Feb 18, 2011 at 12:19 AM, tip-bot for H. Peter Anvin
<hpa@linux.intel.com> wrote:
> Commit-ID:  4822b7fc6d4870685a9feadfc348d48f5e47460a
> Gitweb:     http://git.kernel.org/tip/4822b7fc6d4870685a9feadfc348d48f5e47460a
> Author:     H. Peter Anvin <hpa@linux.intel.com>
> AuthorDate: Mon, 14 Feb 2011 15:34:57 -0800
> Committer:  H. Peter Anvin <hpa@linux.intel.com>
> CommitDate: Thu, 17 Feb 2011 21:02:43 -0800
>
> x86, trampoline: Common infrastructure for low memory trampolines
>
> Common infrastructure for low memory trampolines.  This code installs
> the trampolines permanently in low memory very early.  It also permits
> multiple pieces of code to be used for this purpose.
>
> This code also introduces a standard infrastructure for computing
> symbol addresses in the trampoline code.
>
> The only change to the actual SMP trampolines themselves is that the
> 64-bit trampoline has been made reusable -- the previous version would
> overwrite the code with a status variable; this moves the status
> variable to a separate location.
>
> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
> LKML-Reference: <4D5DFBE4.7090104@intel.com>
> Cc: Rafael J. Wysocki <rjw@sisk.pl>
> Cc: Matthieu Castet <castet.matthieu@free.fr>
> Cc: Stephen Rothwell <sfr@canb.auug.org.au>
> ---
>  arch/x86/Kconfig                |    4 ---
>  arch/x86/kernel/Makefile        |    3 +-
>  arch/x86/kernel/head32.c        |    9 --------
>  arch/x86/kernel/head_64.S       |    3 +-
>  arch/x86/kernel/setup.c         |    2 +-
>  arch/x86/kernel/smpboot.c       |   10 +++++---
>  arch/x86/kernel/trampoline.c    |   42 ++++++++++++++++++++------------------
>  arch/x86/kernel/trampoline_32.S |   15 ++++++++++---
>  arch/x86/kernel/trampoline_64.S |   30 ++++++++++++++++-----------
>  arch/x86/kernel/vmlinux.lds.S   |   13 ++++++++++++
>  10 files changed, 73 insertions(+), 58 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index d5ed94d..1359bc9 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -217,10 +217,6 @@ config X86_HT
>        def_bool y
>        depends on SMP
>
> -config X86_TRAMPOLINE
> -       def_bool y
> -       depends on SMP || (64BIT && ACPI_SLEEP)
> -
>  config X86_32_LAZY_GS
>        def_bool y
>        depends on X86_32 && !CC_STACKPROTECTOR
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 34244b2..2e8ce0d 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -47,7 +47,7 @@ obj-y                 += tsc.o io_delay.o rtc.o
>  obj-y                  += pci-iommu_table.o
>  obj-y                  += resource.o
>
> -obj-$(CONFIG_X86_TRAMPOLINE)   += trampoline.o
> +obj-y                          += trampoline.o trampoline_$(BITS).o
>  obj-y                          += process.o
>  obj-y                          += i387.o xsave.o
>  obj-y                          += ptrace.o
> @@ -69,7 +69,6 @@ obj-$(CONFIG_SMP)             += smp.o
>  obj-$(CONFIG_SMP)              += smpboot.o tsc_sync.o
>  obj-$(CONFIG_SMP)              += setup_percpu.o
>  obj-$(CONFIG_X86_64_SMP)       += tsc_sync.o
> -obj-$(CONFIG_X86_TRAMPOLINE)   += trampoline_$(BITS).o
>  obj-$(CONFIG_X86_MPPARSE)      += mpparse.o
>  obj-y                          += apic/
>  obj-$(CONFIG_X86_REBOOTFIXUPS) += reboot_fixups_32.o
> diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
> index 7f138b3..d6d6bb3 100644
> --- a/arch/x86/kernel/head32.c
> +++ b/arch/x86/kernel/head32.c
> @@ -34,15 +34,6 @@ void __init i386_start_kernel(void)
>  {
>        memblock_init();
>
> -#ifdef CONFIG_X86_TRAMPOLINE
> -       /*
> -        * But first pinch a few for the stack/trampoline stuff
> -        * FIXME: Don't need the extra page at 4K, but need to fix
> -        * trampoline before removing it. (see the GDT stuff)
> -        */
> -       memblock_x86_reserve_range(PAGE_SIZE, PAGE_SIZE + PAGE_SIZE, "EX TRAMPOLINE");
> -#endif
> -
>        memblock_x86_reserve_range(__pa_symbol(&_text), __pa_symbol(&__bss_stop), "TEXT DATA BSS");
>
>  #ifdef CONFIG_BLK_DEV_INITRD
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index 239046b..e11e394 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -136,10 +136,9 @@ ident_complete:
>        /* Fixup phys_base */
>        addq    %rbp, phys_base(%rip)
>
> -#ifdef CONFIG_X86_TRAMPOLINE
> +       /* Fixup trampoline */
>        addq    %rbp, trampoline_level4_pgt + 0(%rip)
>        addq    %rbp, trampoline_level4_pgt + (511*8)(%rip)
> -#endif
>
>        /* Due to ENTRY(), sometimes the empty space gets filled with
>         * zeros. Better take a jmp than relying on empty space being
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index d3cfe26..994ea20 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -935,7 +935,7 @@ void __init setup_arch(char **cmdline_p)
>        printk(KERN_DEBUG "initial memory mapped : 0 - %08lx\n",
>                        max_pfn_mapped<<PAGE_SHIFT);
>
> -       reserve_trampoline_memory();
> +       setup_trampolines();
>
>  #ifdef CONFIG_ACPI_SLEEP
>        /*
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 08776a9..5452733 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -788,7 +788,7 @@ do_rest:
>        stack_start  = c_idle.idle->thread.sp;
>
>        /* start_ip had better be page-aligned! */
> -       start_ip = setup_trampoline();
> +       start_ip = trampoline_address();
>
>        /* So we see what's up */
>        announce_cpu(cpu, apicid);
> @@ -798,6 +798,8 @@ do_rest:
>         * the targeted processor.
>         */
>
> +       printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
> +
>        atomic_set(&init_deasserted, 0);
>
>        if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
> @@ -851,8 +853,8 @@ do_rest:
>                        pr_debug("CPU%d: has booted.\n", cpu);
>                else {
>                        boot_error = 1;
> -                       if (*((volatile unsigned char *)trampoline_base)
> -                                       == 0xA5)
> +                       if (*(volatile u32 *)TRAMPOLINE_SYM(trampoline_status)
> +                           == 0xA5A5A5A5)
>                                /* trampoline started but...? */
>                                pr_err("CPU%d: Stuck ??\n", cpu);
>                        else
> @@ -878,7 +880,7 @@ do_rest:
>        }
>
>        /* mark "stuck" area as not stuck */
> -       *((volatile unsigned long *)trampoline_base) = 0;
> +       *(volatile u32 *)TRAMPOLINE_SYM(trampoline_status) = 0;
>
>        if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
>                /*
> diff --git a/arch/x86/kernel/trampoline.c b/arch/x86/kernel/trampoline.c
> index a375616..a91ae77 100644
> --- a/arch/x86/kernel/trampoline.c
> +++ b/arch/x86/kernel/trampoline.c
> @@ -2,39 +2,41 @@
>  #include <linux/memblock.h>
>
>  #include <asm/trampoline.h>
> +#include <asm/cacheflush.h>
>  #include <asm/pgtable.h>
>
> -#if defined(CONFIG_X86_64) && defined(CONFIG_ACPI_SLEEP)
> -#define __trampinit
> -#define __trampinitdata
> -#else
> -#define __trampinit __cpuinit
> -#define __trampinitdata __cpuinitdata
> -#endif
> +unsigned char *x86_trampoline_base;
>
> -/* ready for x86_64 and x86 */
> -unsigned char *__trampinitdata trampoline_base;
> -
> -void __init reserve_trampoline_memory(void)
> +void __init setup_trampolines(void)
>  {
>        phys_addr_t mem;
> +       size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
>
>        /* Has to be in very low memory so we can execute real-mode AP code. */
> -       mem = memblock_find_in_range(0, 1<<20, TRAMPOLINE_SIZE, PAGE_SIZE);
> +       mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
>        if (mem == MEMBLOCK_ERROR)
>                panic("Cannot allocate trampoline\n");
>
> -       trampoline_base = __va(mem);
> -       memblock_x86_reserve_range(mem, mem + TRAMPOLINE_SIZE, "TRAMPOLINE");
> +       x86_trampoline_base = __va(mem);
> +       memblock_x86_reserve_range(mem, mem + size, "TRAMPOLINE");
> +
> +       printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
> +              x86_trampoline_base, (unsigned long long)mem, size);
> +
> +       memcpy(x86_trampoline_base, x86_trampoline_start, size);
>  }
>
>  /*
> - * Currently trivial. Write the real->protected mode
> - * bootstrap into the page concerned. The caller
> - * has made sure it's suitably aligned.
> + * setup_trampolines() gets called very early, to guarantee the
> + * availability of low memory.  This is before the proper kernel page
> + * tables are set up, so we cannot set page permissions in that
> + * function.  Thus, we use an arch_initcall instead.
>  */
> -unsigned long __trampinit setup_trampoline(void)
> +static int __init configure_trampolines(void)
>  {
> -       memcpy(trampoline_base, trampoline_data, TRAMPOLINE_SIZE);
> -       return virt_to_phys(trampoline_base);
> +       size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
> +
> +       set_memory_x((unsigned long)x86_trampoline_base, size >> PAGE_SHIFT);
> +       return 0;
>  }
> +arch_initcall(configure_trampolines);
> diff --git a/arch/x86/kernel/trampoline_32.S b/arch/x86/kernel/trampoline_32.S
> index 8508237..451c0a7 100644
> --- a/arch/x86/kernel/trampoline_32.S
> +++ b/arch/x86/kernel/trampoline_32.S
> @@ -32,9 +32,11 @@
>  #include <asm/segment.h>
>  #include <asm/page_types.h>
>
> -/* We can free up trampoline after bootup if cpu hotplug is not supported. */
> -__CPUINITRODATA
> -.code16
> +#ifdef CONFIG_SMP
> +
> +       .section ".x86_trampoline","a"
> +       .balign PAGE_SIZE
> +       .code16
>
>  ENTRY(trampoline_data)
>  r_base = .
> @@ -44,7 +46,7 @@ r_base = .
>
>        cli                     # We should be safe anyway
>
> -       movl    $0xA5A5A5A5, trampoline_data - r_base
> +       movl    $0xA5A5A5A5, trampoline_status - r_base
>                                # write marker for master knows we're running
>
>        /* GDT tables in non default location kernel can be beyond 16MB and
> @@ -72,5 +74,10 @@ boot_idt_descr:
>        .word   0                               # idt limit = 0
>        .long   0                               # idt base = 0L
>
> +ENTRY(trampoline_status)
> +       .long   0
> +
>  .globl trampoline_end
>  trampoline_end:
> +
> +#endif /* CONFIG_SMP */
> diff --git a/arch/x86/kernel/trampoline_64.S b/arch/x86/kernel/trampoline_64.S
> index 075d130..49c77a6 100644
> --- a/arch/x86/kernel/trampoline_64.S
> +++ b/arch/x86/kernel/trampoline_64.S
> @@ -32,13 +32,9 @@
>  #include <asm/segment.h>
>  #include <asm/processor-flags.h>
>
> -#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
> +       .section ".x86_trampoline","a"
> +       .balign PAGE_SIZE
> +       .code16
>
>  ENTRY(trampoline_data)
>  r_base = .
> @@ -50,7 +46,7 @@ r_base = .
>        mov     %ax, %ss
>
>
> -       movl    $0xA5A5A5A5, trampoline_data - r_base
> +       movl    $0xA5A5A5A5, trampoline_status - r_base
>                                # write marker for master knows we're running
>
>                                        # Setup stack
> @@ -64,10 +60,13 @@ r_base = .
>        movzx   %ax, %esi               # Find the 32bit trampoline location
>        shll    $4, %esi
>
> -                                       # Fixup the vectors
> -       addl    %esi, startup_32_vector - r_base
> -       addl    %esi, startup_64_vector - r_base
> -       addl    %esi, tgdt + 2 - r_base # Fixup the gdt pointer
> +                                       # Fixup the absolute vectors
> +       leal    (startup_32 - r_base)(%esi), %eax
> +       movl    %eax, startup_32_vector - r_base
> +       leal    (startup_64 - r_base)(%esi), %eax
> +       movl    %eax, startup_64_vector - r_base
> +       leal    (tgdt - r_base)(%esi), %eax
> +       movl    %eax, (tgdt + 2 - r_base)
>
>        /*
>         * GDT tables in non default location kernel can be beyond 16MB and
> @@ -129,6 +128,7 @@ no_longmode:
>        jmp no_longmode
>  #include "verify_cpu.S"
>
> +       .balign 4
>        # Careful these need to be in the same 64K segment as the above;
>  tidt:
>        .word   0                       # idt limit = 0
> @@ -156,6 +156,12 @@ startup_64_vector:
>        .long   startup_64 - r_base
>        .word   __KERNEL_CS, 0
>
> +       .balign 4
> +fixup_base:
> +       .long   0

fixup_base looks unused.

> +ENTRY(trampoline_status)
> +       .long   0
> +
>  trampoline_stack:
>        .org 0x1000
>  trampoline_stack_end:
> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> index bf47007..cb2c506 100644
> --- a/arch/x86/kernel/vmlinux.lds.S
> +++ b/arch/x86/kernel/vmlinux.lds.S
> @@ -240,6 +240,18 @@ SECTIONS
>
>        INIT_DATA_SECTION(16)
>
> +       /*
> +        * Code and data for a variety of lowlevel trampolines, to be
> +        * copied into base memory (< 1 MiB) during initialization.
> +        * Since it is copied early, the main copy can be discarded
> +        * afterwards.
> +        */
> +        .x86_trampoline : AT(ADDR(.x86_trampoline) - LOAD_OFFSET) {
> +               x86_trampoline_start = .;
> +               *(.x86_trampoline)
> +               x86_trampoline_end = .;
> +       }
> +
>        .x86_cpu_dev.init : AT(ADDR(.x86_cpu_dev.init) - LOAD_OFFSET) {
>                __x86_cpu_dev_start = .;
>                *(.x86_cpu_dev.init)
> @@ -291,6 +303,7 @@ SECTIONS
>                *(.iommu_table)
>                __iommu_table_end = .;
>        }
> +
>        . = ALIGN(8);
>        /*
>         * .exit.text is discard at runtime, not link time, to deal with
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

--
Brian Gerst

[tip:x86/trampoline] x86-64, trampoline: Remove unused variable

[tip-bot for H. Peter Anvin]

Commit-ID:  1c4badbdeae53d2584bb5395a062cfebed76696e
Gitweb:     http://git.kernel.org/tip/1c4badbdeae53d2584bb5395a062cfebed76696e
Author:     H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Fri, 18 Feb 2011 15:50:36 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Fri, 18 Feb 2011 15:50:36 -0800

x86-64, trampoline: Remove unused variable

Removed unused variable left over from development.

Reported-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <AANLkTik6UJ680mWJcu_W+jerLcqPjwjvaXyxB1jAMaG0@mail.gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
---
 arch/x86/kernel/trampoline_64.S |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/trampoline_64.S b/arch/x86/kernel/trampoline_64.S
index 49c77a6..09ff517 100644
--- a/arch/x86/kernel/trampoline_64.S
+++ b/arch/x86/kernel/trampoline_64.S
@@ -157,8 +157,6 @@ startup_64_vector:
 	.word	__KERNEL_CS, 0
 
 	.balign 4
-fixup_base:
-	.long	0
 ENTRY(trampoline_status)
 	.long	0
 

Re: [tip:x86/trampoline] x86, trampoline: Common infrastructure for low memory trampolines

[Tony Luck]

On Thu, Feb 17, 2011 at 9:19 PM, tip-bot for H. Peter Anvin
<hpa@linux.intel.com> wrote:
> +       printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
> +

This is kind of noisy on a large system:

Booting Node   0, Processors  #1
smpboot cpu 1: start_ip = 96000
 #2
smpboot cpu 2: start_ip = 96000
 #3
smpboot cpu 3: start_ip = 96000
 #4
smpboot cpu 4: start_ip = 96000
 #5
smpboot cpu 5: start_ip = 96000
  ... continues for every cpu ...

and doesn't really look all that useful. Can we drop it?

-Tony

Re: [tip:x86/trampoline] x86, trampoline: Common infrastructure for low memory trampolines

[H. Peter Anvin]

On 08/23/2011 12:05 PM, Tony Luck wrote:
> On Thu, Feb 17, 2011 at 9:19 PM, tip-bot for H. Peter Anvin
> <hpa@linux.intel.com> wrote:
>> +       printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
>> +
> 
> This is kind of noisy on a large system:
> 
> Booting Node   0, Processors  #1
> smpboot cpu 1: start_ip = 96000
>  #2
> smpboot cpu 2: start_ip = 96000
>  #3
> smpboot cpu 3: start_ip = 96000
>  #4
> smpboot cpu 4: start_ip = 96000
>  #5
> smpboot cpu 5: start_ip = 96000
>   ... continues for every cpu ...
> 
> and doesn't really look all that useful. Can we drop it?
> 

Right, there haven't been any issues with this so we can just drop it.

	-hpa

[PATCH] x86: remove some noise from boot log when starting cpus

[Luck, Tony]

Printing the "start_ip" for every secondary cpu is very noisy on a large
system - and doesn't add any value. Drop this message.

Signed-off-by: Tony Luck <tony.luck@intel.com>

---

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9f548cb..fe5fb7a 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -734,8 +734,6 @@ do_rest:
 	 * the targeted processor.
 	 */
 
-	printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
-
 	atomic_set(&init_deasserted, 0);
 
 	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {

Re: [PATCH] x86: remove some noise from boot log when starting cpus

[Borislav Petkov]

On Tue, Aug 23, 2011 at 01:26:26PM -0700, Luck, Tony wrote:
> Printing the "start_ip" for every secondary cpu is very noisy on a large
> system - and doesn't add any value. Drop this message.
> 
> Signed-off-by: Tony Luck <tony.luck@intel.com>

This one is still out-of-tree, can we pick it up pls?

Thanks.

> 
> ---
> 
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 9f548cb..fe5fb7a 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -734,8 +734,6 @@ do_rest:
>  	 * the targeted processor.
>  	 */
>  
> -	printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
> -
>  	atomic_set(&init_deasserted, 0);
>  
>  	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
Regards/Gruss,
Boris.

Re: [PATCH] x86: remove some noise from boot log when starting cpus

[Ingo Molnar]

* Borislav Petkov <bp@alien8.de> wrote:

> On Tue, Aug 23, 2011 at 01:26:26PM -0700, Luck, Tony wrote:
> > Printing the "start_ip" for every secondary cpu is very noisy on a large
> > system - and doesn't add any value. Drop this message.
> > 
> > Signed-off-by: Tony Luck <tony.luck@intel.com>
> 
> This one is still out-of-tree, can we pick it up pls?

Seems rather old - please resubmit and make sure it still works 
as expected, etc.

Thanks,

	Ingo

Re: [PATCH] x86: remove some noise from boot log when starting cpus

[Borislav Petkov]

On Wed, Feb 22, 2012 at 11:33:48AM +0100, Ingo Molnar wrote:
> 
> * Borislav Petkov <bp@alien8.de> wrote:
> 
> > On Tue, Aug 23, 2011 at 01:26:26PM -0700, Luck, Tony wrote:
> > > Printing the "start_ip" for every secondary cpu is very noisy on a large
> > > system - and doesn't add any value. Drop this message.
> > > 
> > > Signed-off-by: Tony Luck <tony.luck@intel.com>
> > 
> > This one is still out-of-tree, can we pick it up pls?
> 
> Seems rather old - please resubmit and make sure it still works 
> as expected, etc.

Yeah, I'll leave that to Tony. I could then verify it works although it
is trivial enough and could go in even now.

-- 
Regards/Gruss,
Boris.

Re: [PATCH] x86: remove some noise from boot log when starting cpus

[Ingo Molnar]

* Borislav Petkov <bp@alien8.de> wrote:

> On Wed, Feb 22, 2012 at 11:33:48AM +0100, Ingo Molnar wrote:
> > 
> > * Borislav Petkov <bp@alien8.de> wrote:
> > 
> > > On Tue, Aug 23, 2011 at 01:26:26PM -0700, Luck, Tony wrote:
> > > > Printing the "start_ip" for every secondary cpu is very noisy on a large
> > > > system - and doesn't add any value. Drop this message.
> > > > 
> > > > Signed-off-by: Tony Luck <tony.luck@intel.com>
> > > 
> > > This one is still out-of-tree, can we pick it up pls?
> > 
> > Seems rather old - please resubmit and make sure it still works 
> > as expected, etc.
> 
> Yeah, I'll leave that to Tony. I could then verify it works although it
> is trivial enough and could go in even now.

fine with me - please resend nevertheless.

Thanks,

	Ingo

[PATCH/resubmit] x86: Remove some noise from boot log when starting cpus

[Luck, Tony]

Printing the "start_ip" for every secondary cpu is very noisy on a large
system - and doesn't add any value. Drop this message.

Console log before:
Booting Node   0, Processors  #1
smpboot cpu 1: start_ip = 96000
 #2
smpboot cpu 2: start_ip = 96000
 #3
smpboot cpu 3: start_ip = 96000
 #4
smpboot cpu 4: start_ip = 96000
       ...
 #31
smpboot cpu 31: start_ip = 96000
Brought up 32 CPUs

Console log after:
Booting Node   0, Processors  #1 #2 #3 #4 #5 #6 #7 Ok.
Booting Node   1, Processors  #8 #9 #10 #11 #12 #13 #14 #15 Ok.
Booting Node   0, Processors  #16 #17 #18 #19 #20 #21 #22 #23 Ok.
Booting Node   1, Processors  #24 #25 #26 #27 #28 #29 #30 #31
Brought up 32 CPUs

Acked-by: Borislav Petkov <bp@amd64.org>
Link: https://lkml.org/lkml/2012/2/22/144
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 arch/x86/kernel/smpboot.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)


diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 66d250c..6835752 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -740,8 +740,6 @@ do_rest:
 	 * the targeted processor.
 	 */
 
-	printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
-
 	atomic_set(&init_deasserted, 0);
 
 	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
-- 
1.7.9.rc2.1.g69204

[tip:x86/cpu] x86: Remove some noise from boot log when starting cpus

[tip-bot for Luck, Tony]

Commit-ID:  140f190bc3a3b6f200548d204befd998eadd63fd
Gitweb:     http://git.kernel.org/tip/140f190bc3a3b6f200548d204befd998eadd63fd
Author:     Luck, Tony <tony.luck@intel.com>
AuthorDate: Wed, 22 Feb 2012 10:06:44 -0800
Committer:  H. Peter Anvin <hpa@zytor.com>
CommitDate: Wed, 22 Feb 2012 10:11:05 -0800

x86: Remove some noise from boot log when starting cpus

Printing the "start_ip" for every secondary cpu is very noisy on a large
system - and doesn't add any value. Drop this message.

Console log before:
Booting Node   0, Processors  #1
smpboot cpu 1: start_ip = 96000
 #2
smpboot cpu 2: start_ip = 96000
 #3
smpboot cpu 3: start_ip = 96000
 #4
smpboot cpu 4: start_ip = 96000
       ...
 #31
smpboot cpu 31: start_ip = 96000
Brought up 32 CPUs

Console log after:
Booting Node   0, Processors  #1 #2 #3 #4 #5 #6 #7 Ok.
Booting Node   1, Processors  #8 #9 #10 #11 #12 #13 #14 #15 Ok.
Booting Node   0, Processors  #16 #17 #18 #19 #20 #21 #22 #23 Ok.
Booting Node   1, Processors  #24 #25 #26 #27 #28 #29 #30 #31
Brought up 32 CPUs

Acked-by: Borislav Petkov <bp@amd64.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/4f452eb42507460426@agluck-desktop.sc.intel.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/kernel/smpboot.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 66d250c..6835752 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -740,8 +740,6 @@ do_rest:
 	 * the targeted processor.
 	 */
 
-	printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
-
 	atomic_set(&init_deasserted, 0);
 
 	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {

[tip:x86/debug] x86/debug: Remove ancient debugging noise from boot log when starting cpus

[tip-bot for Luck, Tony]

Commit-ID:  55bc423c1274ba474b74155167d33a56ddf77558
Gitweb:     http://git.kernel.org/tip/55bc423c1274ba474b74155167d33a56ddf77558
Author:     Luck, Tony <tony.luck@intel.com>
AuthorDate: Wed, 22 Feb 2012 10:06:44 -0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 22 Feb 2012 21:26:18 +0100

x86/debug: Remove ancient debugging noise from boot log when starting cpus

Printing the "start_ip" for every secondary cpu is very noisy on
a large system - and doesn't add any value. Drop this message.

Console log before:

 Booting Node   0, Processors  #1
 smpboot cpu 1: start_ip = 96000
  #2
 smpboot cpu 2: start_ip = 96000
  #3
 smpboot cpu 3: start_ip = 96000
  #4
 smpboot cpu 4: start_ip = 96000
        ...
  #31
 smpboot cpu 31: start_ip = 96000
 Brought up 32 CPUs

Console log after:

 Booting Node   0, Processors  #1 #2 #3 #4 #5 #6 #7 Ok.
 Booting Node   1, Processors  #8 #9 #10 #11 #12 #13 #14 #15 Ok.
 Booting Node   0, Processors  #16 #17 #18 #19 #20 #21 #22 #23 Ok.
 Booting Node   1, Processors  #24 #25 #26 #27 #28 #29 #30
 #31 Brought up 32 CPUs

Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Borislav Petkov <bp@amd64.org>
Cc: castet.matthieu@free.fr
Cc: sfr@canb.auug.org.au
Cc: hpa@linux.intel.com
Cc: rjw@sisk.pl
Link: http://lkml.kernel.org/r/4f452eb42507460426@agluck-desktop.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/smpboot.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 257049d..f34f8b2 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -740,8 +740,6 @@ do_rest:
 	 * the targeted processor.
 	 */
 
-	printk(KERN_DEBUG "smpboot cpu %d: start_ip = %lx\n", cpu, start_ip);
-
 	atomic_set(&init_deasserted, 0);
 
 	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {

[tip:x86/trampoline] x86, trampoline: Use the unified trampoline setup for ACPI wakeup

[tip-bot for H. Peter Anvin]

Commit-ID:  d1ee433539ea5963a8f946f3428b335d1c5fdb20
Gitweb:     http://git.kernel.org/tip/d1ee433539ea5963a8f946f3428b335d1c5fdb20
Author:     H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Mon, 14 Feb 2011 15:42:46 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 17 Feb 2011 21:05:06 -0800

x86, trampoline: Use the unified trampoline setup for ACPI wakeup

Use the unified trampoline allocation setup to allocate and install
the ACPI wakeup code in low memory.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4D5DFBE4.7090104@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
---
 arch/x86/include/asm/acpi.h                |    4 +-
 arch/x86/include/asm/trampoline.h          |   33 +++++++++-----
 arch/x86/kernel/acpi/realmode/wakeup.S     |   21 ++++++---
 arch/x86/kernel/acpi/realmode/wakeup.h     |    5 +-
 arch/x86/kernel/acpi/realmode/wakeup.lds.S |   28 ++++++------
 arch/x86/kernel/acpi/sleep.c               |   65 +++-------------------------
 arch/x86/kernel/acpi/sleep.h               |    3 -
 arch/x86/kernel/acpi/wakeup_rm.S           |   10 +++--
 arch/x86/kernel/setup.c                    |    7 ---
 drivers/acpi/sleep.c                       |    1 +
 10 files changed, 69 insertions(+), 108 deletions(-)

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 211ca3f..4784df5 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -29,6 +29,7 @@
 #include <asm/processor.h>
 #include <asm/mmu.h>
 #include <asm/mpspec.h>
+#include <asm/trampoline.h>
 
 #define COMPILER_DEPENDENT_INT64   long long
 #define COMPILER_DEPENDENT_UINT64  unsigned long long
@@ -116,7 +117,8 @@ static inline void acpi_disable_pci(void)
 extern int acpi_save_state_mem(void);
 extern void acpi_restore_state_mem(void);
 
-extern unsigned long acpi_wakeup_address;
+extern const unsigned char acpi_wakeup_code[];
+#define acpi_wakeup_address (__pa(TRAMPOLINE_SYM(acpi_wakeup_code)))
 
 /* early initialization routine */
 extern void acpi_reserve_wakeup_memory(void);
diff --git a/arch/x86/include/asm/trampoline.h b/arch/x86/include/asm/trampoline.h
index f4500fb..feca311 100644
--- a/arch/x86/include/asm/trampoline.h
+++ b/arch/x86/include/asm/trampoline.h
@@ -3,25 +3,36 @@
 
 #ifndef __ASSEMBLY__
 
-#ifdef CONFIG_X86_TRAMPOLINE
+#include <linux/types.h>
+#include <asm/io.h>
+
 /*
- * Trampoline 80x86 program as an array.
+ * Trampoline 80x86 program as an array.  These are in the init rodata
+ * segment, but that's okay, because we only care about the relative
+ * addresses of the symbols.
  */
-extern const unsigned char trampoline_data [];
-extern const unsigned char trampoline_end  [];
-extern unsigned char *trampoline_base;
+extern const unsigned char x86_trampoline_start [];
+extern const unsigned char x86_trampoline_end   [];
+extern unsigned char *x86_trampoline_base;
 
 extern unsigned long init_rsp;
 extern unsigned long initial_code;
 extern unsigned long initial_gs;
 
-#define TRAMPOLINE_SIZE roundup(trampoline_end - trampoline_data, PAGE_SIZE)
+extern void __init setup_trampolines(void);
+
+extern const unsigned char trampoline_data[];
+extern const unsigned char trampoline_status[];
+
+#define TRAMPOLINE_SYM(x)						\
+	((void *)(x86_trampoline_base +					\
+		  ((const unsigned char *)(x) - x86_trampoline_start)))
 
-extern unsigned long setup_trampoline(void);
-extern void __init reserve_trampoline_memory(void);
-#else
-static inline void reserve_trampoline_memory(void) {}
-#endif /* CONFIG_X86_TRAMPOLINE */
+/* Address of the SMP trampoline */
+static inline unsigned long trampoline_address(void)
+{
+	return virt_to_phys(TRAMPOLINE_SYM(trampoline_data));
+}
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/x86/kernel/acpi/realmode/wakeup.S b/arch/x86/kernel/acpi/realmode/wakeup.S
index 28595d6..ead21b6 100644
--- a/arch/x86/kernel/acpi/realmode/wakeup.S
+++ b/arch/x86/kernel/acpi/realmode/wakeup.S
@@ -6,11 +6,17 @@
 #include <asm/page_types.h>
 #include <asm/pgtable_types.h>
 #include <asm/processor-flags.h>
+#include "wakeup.h"
 
 	.code16
-	.section ".header", "a"
+	.section ".jump", "ax"
+	.globl	_start
+_start:
+	cli
+	jmp	wakeup_code
 
 /* This should match the structure in wakeup.h */
+		.section ".header", "a"
 		.globl	wakeup_header
 wakeup_header:
 video_mode:	.short	0	/* Video mode number */
@@ -30,14 +36,11 @@ wakeup_jmp:	.byte	0xea	/* ljmpw */
 wakeup_jmp_off:	.word	3f
 wakeup_jmp_seg:	.word	0
 wakeup_gdt:	.quad	0, 0, 0
-signature:	.long	0x51ee1111
+signature:	.long	WAKEUP_HEADER_SIGNATURE
 
 	.text
-	.globl	_start
 	.code16
 wakeup_code:
-_start:
-	cli
 	cld
 
 	/* Apparently some dimwit BIOS programmers don't know how to
@@ -77,12 +80,12 @@ _start:
 
 	/* Check header signature... */
 	movl	signature, %eax
-	cmpl	$0x51ee1111, %eax
+	cmpl	$WAKEUP_HEADER_SIGNATURE, %eax
 	jne	bogus_real_magic
 
 	/* Check we really have everything... */
 	movl	end_signature, %eax
-	cmpl	$0x65a22c82, %eax
+	cmpl	$WAKEUP_END_SIGNATURE, %eax
 	jne	bogus_real_magic
 
 	/* Call the C code */
@@ -147,3 +150,7 @@ wakeup_heap:
 wakeup_stack:
 	.space	2048
 wakeup_stack_end:
+
+	.section ".signature","a"
+end_signature:
+	.long	WAKEUP_END_SIGNATURE
diff --git a/arch/x86/kernel/acpi/realmode/wakeup.h b/arch/x86/kernel/acpi/realmode/wakeup.h
index 69d38d0..e1828c0 100644
--- a/arch/x86/kernel/acpi/realmode/wakeup.h
+++ b/arch/x86/kernel/acpi/realmode/wakeup.h
@@ -35,7 +35,8 @@ struct wakeup_header {
 extern struct wakeup_header wakeup_header;
 #endif
 
-#define HEADER_OFFSET 0x3f00
-#define WAKEUP_SIZE   0x4000
+#define WAKEUP_HEADER_OFFSET	8
+#define WAKEUP_HEADER_SIGNATURE 0x51ee1111
+#define WAKEUP_END_SIGNATURE	0x65a22c82
 
 #endif /* ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H */
diff --git a/arch/x86/kernel/acpi/realmode/wakeup.lds.S b/arch/x86/kernel/acpi/realmode/wakeup.lds.S
index 060fff8..d4f8010 100644
--- a/arch/x86/kernel/acpi/realmode/wakeup.lds.S
+++ b/arch/x86/kernel/acpi/realmode/wakeup.lds.S
@@ -13,9 +13,19 @@ ENTRY(_start)
 SECTIONS
 {
 	. = 0;
+	.jump	: {
+		*(.jump)
+	} = 0x90909090
+
+	. = WAKEUP_HEADER_OFFSET;
+	.header : {
+		*(.header)
+	}
+
+	. = ALIGN(16);
 	.text : {
 		 *(.text*)
-	}
+	} = 0x90909090
 
 	. = ALIGN(16);
 	.rodata : {
@@ -33,11 +43,6 @@ SECTIONS
 		 *(.data*)
 	}
 
-	.signature : {
-		end_signature = .;
-		LONG(0x65a22c82)
-	}
-
 	. = ALIGN(16);
 	.bss :	{
 		__bss_start = .;
@@ -45,20 +50,13 @@ SECTIONS
 		__bss_end = .;
 	}
 
-	. = HEADER_OFFSET;
-	.header : {
-		*(.header)
+	.signature : {
+		*(.signature)
 	}
 
-	. = ALIGN(16);
 	_end = .;
 
 	/DISCARD/ : {
 		*(.note*)
 	}
-
-	/*
-	 * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
-	 */
-	. = ASSERT(_end <= WAKEUP_SIZE, "Wakeup too big!");
 }
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 68d1537..4572c58 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -18,12 +18,8 @@
 #include "realmode/wakeup.h"
 #include "sleep.h"
 
-unsigned long acpi_wakeup_address;
 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)
 static char temp_stack[4096];
 #endif
@@ -33,22 +29,17 @@ static char temp_stack[4096];
  *
  * Create an identity mapped page table and copy the wakeup routine to
  * low memory.
- *
- * Note that this is too late to change acpi_wakeup_address.
  */
 int acpi_save_state_mem(void)
 {
 	struct wakeup_header *header;
+	/* address in low memory of the wakeup routine. */
+	char *acpi_realmode;
 
-	if (!acpi_realmode) {
-		printk(KERN_ERR "Could not allocate memory during boot, "
-		       "S3 disabled\n");
-		return -ENOMEM;
-	}
-	memcpy((void *)acpi_realmode, &wakeup_code_start, WAKEUP_SIZE);
+	acpi_realmode = TRAMPOLINE_SYM(acpi_wakeup_code);
 
-	header = (struct wakeup_header *)(acpi_realmode + HEADER_OFFSET);
-	if (header->signature != 0x51ee1111) {
+	header = (struct wakeup_header *)(acpi_realmode + WAKEUP_HEADER_OFFSET);
+	if (header->signature != WAKEUP_HEADER_SIGNATURE) {
 		printk(KERN_ERR "wakeup header does not match\n");
 		return -EINVAL;
 	}
@@ -68,9 +59,7 @@ int acpi_save_state_mem(void)
 	/* GDT[0]: GDT self-pointer */
 	header->wakeup_gdt[0] =
 		(u64)(sizeof(header->wakeup_gdt) - 1) +
-		((u64)(acpi_wakeup_address +
-			((char *)&header->wakeup_gdt - (char *)acpi_realmode))
-				<< 16);
+		((u64)__pa(&header->wakeup_gdt) << 16);
 	/* GDT[1]: big real mode-like code segment */
 	header->wakeup_gdt[1] =
 		GDT_ENTRY(0x809b, acpi_wakeup_address, 0xfffff);
@@ -96,7 +85,7 @@ int acpi_save_state_mem(void)
 	header->pmode_cr3 = (u32)__pa(&initial_page_table);
 	saved_magic = 0x12345678;
 #else /* CONFIG_64BIT */
-	header->trampoline_segment = setup_trampoline() >> 4;
+	header->trampoline_segment = trampoline_address() >> 4;
 #ifdef CONFIG_SMP
 	stack_start = (unsigned long)temp_stack + sizeof(temp_stack);
 	early_gdt_descr.address =
@@ -117,46 +106,6 @@ void acpi_restore_state_mem(void)
 {
 }
 
-
-/**
- * acpi_reserve_wakeup_memory - do _very_ early ACPI initialisation
- *
- * We allocate a page from the first 1MB of memory for the wakeup
- * routine for when we come back from a sleep state. The
- * runtime allocator allows specification of <16MB pages, but not
- * <1MB pages.
- */
-void __init acpi_reserve_wakeup_memory(void)
-{
-	phys_addr_t mem;
-
-	if ((&wakeup_code_end - &wakeup_code_start) > WAKEUP_SIZE) {
-		printk(KERN_ERR
-		       "ACPI: Wakeup code way too big, S3 disabled.\n");
-		return;
-	}
-
-	mem = memblock_find_in_range(0, 1<<20, WAKEUP_SIZE, PAGE_SIZE);
-
-	if (mem == MEMBLOCK_ERROR) {
-		printk(KERN_ERR "ACPI: Cannot allocate lowmem, S3 disabled.\n");
-		return;
-	}
-	acpi_realmode = (unsigned long) phys_to_virt(mem);
-	acpi_wakeup_address = mem;
-	memblock_x86_reserve_range(mem, mem + WAKEUP_SIZE, "ACPI WAKEUP");
-}
-
-int __init acpi_configure_wakeup_memory(void)
-{
-	if (acpi_realmode)
-		set_memory_x(acpi_realmode, WAKEUP_SIZE >> PAGE_SHIFT);
-
-	return 0;
-}
-arch_initcall(acpi_configure_wakeup_memory);
-
-
 static int __init acpi_sleep_setup(char *str)
 {
 	while ((str != NULL) && (*str != '\0')) {
diff --git a/arch/x86/kernel/acpi/sleep.h b/arch/x86/kernel/acpi/sleep.h
index adbcbaa..86ba1c8 100644
--- a/arch/x86/kernel/acpi/sleep.h
+++ b/arch/x86/kernel/acpi/sleep.h
@@ -4,13 +4,10 @@
 
 #include <asm/trampoline.h>
 
-extern char wakeup_code_start, wakeup_code_end;
-
 extern unsigned long saved_video_mode;
 extern long saved_magic;
 
 extern int wakeup_pmode_return;
-extern char swsusp_pg_dir[PAGE_SIZE];
 
 extern unsigned long acpi_copy_wakeup_routine(unsigned long);
 extern void wakeup_long64(void);
diff --git a/arch/x86/kernel/acpi/wakeup_rm.S b/arch/x86/kernel/acpi/wakeup_rm.S
index 6ff3b57..6ce81ee 100644
--- a/arch/x86/kernel/acpi/wakeup_rm.S
+++ b/arch/x86/kernel/acpi/wakeup_rm.S
@@ -2,9 +2,11 @@
  * Wrapper script for the realmode binary as a transport object
  * before copying to low memory.
  */
-	.section ".rodata","a"
-	.globl	wakeup_code_start, wakeup_code_end
-wakeup_code_start:
+#include <asm/page_types.h>
+
+	.section ".x86_trampoline","a"
+	.balign PAGE_SIZE
+	.globl	acpi_wakeup_code
+acpi_wakeup_code:
 	.incbin	"arch/x86/kernel/acpi/realmode/wakeup.bin"
-wakeup_code_end:
 	.size	wakeup_code_start, .-wakeup_code_start
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 994ea20..a089fc1 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -937,13 +937,6 @@ void __init setup_arch(char **cmdline_p)
 
 	setup_trampolines();
 
-#ifdef CONFIG_ACPI_SLEEP
-	/*
-	 * Reserve low memory region for sleep support.
-	 * even before init_memory_mapping
-	 */
-	acpi_reserve_wakeup_memory();
-#endif
 	init_gbpages();
 
 	/* max_pfn_mapped is updated here */
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index d6a8cd1..e9fef94 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -16,6 +16,7 @@
 #include <linux/device.h>
 #include <linux/suspend.h>
 #include <linux/reboot.h>
+#include <linux/acpi.h>
 
 #include <asm/io.h>
 

Re: [tip:x86/trampoline] x86, trampoline: Use the unified trampoline setup for ACPI wakeup

[matthieu castet]

Hi,

tip-bot for H. Peter Anvin a écrit :
> Commit-ID:  d1ee433539ea5963a8f946f3428b335d1c5fdb20
> Gitweb:     http://git.kernel.org/tip/d1ee433539ea5963a8f946f3428b335d1c5fdb20
> Author:     H. Peter Anvin <hpa@linux.intel.com>
> AuthorDate: Mon, 14 Feb 2011 15:42:46 -0800
> Committer:  H. Peter Anvin <hpa@linux.intel.com>
> CommitDate: Thu, 17 Feb 2011 21:05:06 -0800
> 
> diff --git a/arch/x86/kernel/acpi/wakeup_rm.S b/arch/x86/kernel/acpi/wakeup_rm.S
> index 6ff3b57..6ce81ee 100644
> --- a/arch/x86/kernel/acpi/wakeup_rm.S
> +++ b/arch/x86/kernel/acpi/wakeup_rm.S
> @@ -2,9 +2,11 @@
>   * Wrapper script for the realmode binary as a transport object
>   * before copying to low memory.
>   */
> -	.section ".rodata","a"
> -	.globl	wakeup_code_start, wakeup_code_end
> -wakeup_code_start:
> +#include <asm/page_types.h>
> +
> +	.section ".x86_trampoline","a"
> +	.balign PAGE_SIZE
> +	.globl	acpi_wakeup_code
> +acpi_wakeup_code:
>  	.incbin	"arch/x86/kernel/acpi/realmode/wakeup.bin"
> -wakeup_code_end:
>  	.size	wakeup_code_start, .-wakeup_code_start
It doesn't build for me, Shouldn't you change this to 
.size	acpi_wakeup_code, .-acpi_wakeup_code ?


Matthieu

Re: [tip:x86/trampoline] x86, trampoline: Use the unified trampoline setup for ACPI wakeup

[Rafael J. Wysocki]

On Wednesday, March 09, 2011, matthieu castet wrote:
> Hi,
> 
> tip-bot for H. Peter Anvin a écrit :
> > Commit-ID:  d1ee433539ea5963a8f946f3428b335d1c5fdb20
> > Gitweb:     http://git.kernel.org/tip/d1ee433539ea5963a8f946f3428b335d1c5fdb20
> > Author:     H. Peter Anvin <hpa@linux.intel.com>
> > AuthorDate: Mon, 14 Feb 2011 15:42:46 -0800
> > Committer:  H. Peter Anvin <hpa@linux.intel.com>
> > CommitDate: Thu, 17 Feb 2011 21:05:06 -0800
> > 
> > diff --git a/arch/x86/kernel/acpi/wakeup_rm.S b/arch/x86/kernel/acpi/wakeup_rm.S
> > index 6ff3b57..6ce81ee 100644
> > --- a/arch/x86/kernel/acpi/wakeup_rm.S
> > +++ b/arch/x86/kernel/acpi/wakeup_rm.S
> > @@ -2,9 +2,11 @@
> >   * Wrapper script for the realmode binary as a transport object
> >   * before copying to low memory.
> >   */
> > -	.section ".rodata","a"
> > -	.globl	wakeup_code_start, wakeup_code_end
> > -wakeup_code_start:
> > +#include <asm/page_types.h>
> > +
> > +	.section ".x86_trampoline","a"
> > +	.balign PAGE_SIZE
> > +	.globl	acpi_wakeup_code
> > +acpi_wakeup_code:
> >  	.incbin	"arch/x86/kernel/acpi/realmode/wakeup.bin"
> > -wakeup_code_end:
> >  	.size	wakeup_code_start, .-wakeup_code_start
> It doesn't build for me, Shouldn't you change this to 
> .size	acpi_wakeup_code, .-acpi_wakeup_code ?

Yes, and the fix is already in the tip tree.

Thanks,
Rafael

[tip:x86/trampoline] x86: Make the GDT_ENTRY() macro in <asm/segment.h> safe for assembly

[tip-bot for H. Peter Anvin]

Commit-ID:  014eea518af3d141e276664cf40ef3da899eba35
Gitweb:     http://git.kernel.org/tip/014eea518af3d141e276664cf40ef3da899eba35
Author:     H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Mon, 14 Feb 2011 18:33:55 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 17 Feb 2011 21:05:13 -0800

x86: Make the GDT_ENTRY() macro in <asm/segment.h> safe for assembly

Make the GDT_ENTRY() macro in  <asm/segment.h> safe for use in
assembly code by guarding the ULL suffixes with _AC() macros.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4D5DFBE4.7090104@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
---
 arch/x86/include/asm/segment.h |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index 231f1c1..cd84f72 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -1,14 +1,16 @@
 #ifndef _ASM_X86_SEGMENT_H
 #define _ASM_X86_SEGMENT_H
 
+#include <linux/const.h>
+
 /* Constructor for a conventional segment GDT (or LDT) entry */
 /* This is a macro so it can be used in initializers */
 #define GDT_ENTRY(flags, base, limit)			\
-	((((base)  & 0xff000000ULL) << (56-24)) |	\
-	 (((flags) & 0x0000f0ffULL) << 40) |		\
-	 (((limit) & 0x000f0000ULL) << (48-16)) |	\
-	 (((base)  & 0x00ffffffULL) << 16) |		\
-	 (((limit) & 0x0000ffffULL)))
+	((((base)  & _AC(0xff000000,ULL)) << (56-24)) |	\
+	 (((flags) & _AC(0x0000f0ff,ULL)) << 40) |	\
+	 (((limit) & _AC(0x000f0000,ULL)) << (48-16)) |	\
+	 (((base)  & _AC(0x00ffffff,ULL)) << 16) |	\
+	 (((limit) & _AC(0x0000ffff,ULL))))
 
 /* Simple and small GDT entries for booting only */
 

[tip:x86/trampoline] x86, reboot: Move the real-mode reboot code to an assembly file

[tip-bot for H. Peter Anvin]

Commit-ID:  3d35ac346e981162eeba391e496faceed4753e7b
Gitweb:     http://git.kernel.org/tip/3d35ac346e981162eeba391e496faceed4753e7b
Author:     H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Mon, 14 Feb 2011 18:36:03 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 17 Feb 2011 21:05:34 -0800

x86, reboot: Move the real-mode reboot code to an assembly file

Move the real-mode reboot code out to an assembly file (reboot_32.S)
which is allocated using the common lowmem trampoline allocator.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4D5DFBE4.7090104@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
---
 arch/x86/include/asm/reboot.h |    5 +-
 arch/x86/kernel/Makefile      |    1 +
 arch/x86/kernel/apm_32.c      |   12 +----
 arch/x86/kernel/reboot.c      |  120 ++++++++-----------------------------
 arch/x86/kernel/reboot_32.S   |  131 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 162 insertions(+), 107 deletions(-)

diff --git a/arch/x86/include/asm/reboot.h b/arch/x86/include/asm/reboot.h
index 562d4fd..3250e3d 100644
--- a/arch/x86/include/asm/reboot.h
+++ b/arch/x86/include/asm/reboot.h
@@ -18,7 +18,10 @@ extern struct machine_ops machine_ops;
 
 void native_machine_crash_shutdown(struct pt_regs *regs);
 void native_machine_shutdown(void);
-void machine_real_restart(const unsigned char *code, int length);
+void machine_real_restart(unsigned int type);
+/* These must match dispatch_table in reboot_32.S */
+#define MRR_BIOS	0
+#define MRR_APM		1
 
 typedef void (*nmi_shootdown_cb)(int, struct die_args*);
 void nmi_shootdown_cpus(nmi_shootdown_cb callback);
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 2e8ce0d..778c5b93 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-y				+= cpu/
 obj-y				+= acpi/
 obj-y				+= reboot.o
+obj-$(CONFIG_X86_32)		+= reboot_32.o
 obj-$(CONFIG_MCA)		+= mca_32.o
 obj-$(CONFIG_X86_MSR)		+= msr.o
 obj-$(CONFIG_X86_CPUID)		+= cpuid.o
diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 0e4f24c..b929108 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -975,20 +975,10 @@ recalc:
 
 static void apm_power_off(void)
 {
-	unsigned char po_bios_call[] = {
-		0xb8, 0x00, 0x10,	/* movw  $0x1000,ax  */
-		0x8e, 0xd0,		/* movw  ax,ss       */
-		0xbc, 0x00, 0xf0,	/* movw  $0xf000,sp  */
-		0xb8, 0x07, 0x53,	/* movw  $0x5307,ax  */
-		0xbb, 0x01, 0x00,	/* movw  $0x0001,bx  */
-		0xb9, 0x03, 0x00,	/* movw  $0x0003,cx  */
-		0xcd, 0x15		/* int   $0x15       */
-	};
-
 	/* Some bioses don't like being called from CPU != 0 */
 	if (apm_info.realmode_power_off) {
 		set_cpus_allowed_ptr(current, cpumask_of(0));
-		machine_real_restart(po_bios_call, sizeof(po_bios_call));
+		machine_real_restart(MRR_APM);
 	} else {
 		(void)set_system_power_state(APM_STATE_OFF);
 	}
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index fc7aae1..10c6619 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -295,68 +295,16 @@ static int __init reboot_init(void)
 }
 core_initcall(reboot_init);
 
-/* The following code and data reboots the machine by switching to real
-   mode and jumping to the BIOS reset entry point, as if the CPU has
-   really been reset.  The previous version asked the keyboard
-   controller to pulse the CPU reset line, which is more thorough, but
-   doesn't work with at least one type of 486 motherboard.  It is easy
-   to stop this code working; hence the copious comments. */
-static const unsigned long long
-real_mode_gdt_entries [3] =
-{
-	0x0000000000000000ULL,	/* Null descriptor */
-	0x00009b000000ffffULL,	/* 16-bit real-mode 64k code at 0x00000000 */
-	0x000093000100ffffULL	/* 16-bit real-mode 64k data at 0x00000100 */
-};
+extern const unsigned char machine_real_restart_asm[];
+extern const u64 machine_real_restart_gdt[3];
 
-static const struct desc_ptr
-real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, (long)real_mode_gdt_entries },
-real_mode_idt = { 0x3ff, 0 };
-
-/* This is 16-bit protected mode code to disable paging and the cache,
-   switch to real mode and jump to the BIOS reset code.
-
-   The instruction that switches to real mode by writing to CR0 must be
-   followed immediately by a far jump instruction, which set CS to a
-   valid value for real mode, and flushes the prefetch queue to avoid
-   running instructions that have already been decoded in protected
-   mode.
-
-   Clears all the flags except ET, especially PG (paging), PE
-   (protected-mode enable) and TS (task switch for coprocessor state
-   save).  Flushes the TLB after paging has been disabled.  Sets CD and
-   NW, to disable the cache on a 486, and invalidates the cache.  This
-   is more like the state of a 486 after reset.  I don't know if
-   something else should be done for other chips.
-
-   More could be done here to set up the registers as if a CPU reset had
-   occurred; hopefully real BIOSs don't assume much. */
-static const unsigned char real_mode_switch [] =
-{
-	0x66, 0x0f, 0x20, 0xc0,			/*    movl  %cr0,%eax        */
-	0x66, 0x83, 0xe0, 0x11,			/*    andl  $0x00000011,%eax */
-	0x66, 0x0d, 0x00, 0x00, 0x00, 0x60,	/*    orl   $0x60000000,%eax */
-	0x66, 0x0f, 0x22, 0xc0,			/*    movl  %eax,%cr0        */
-	0x66, 0x0f, 0x22, 0xd8,			/*    movl  %eax,%cr3        */
-	0x66, 0x0f, 0x20, 0xc3,			/*    movl  %cr0,%ebx        */
-	0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60,	/*    andl  $0x60000000,%ebx */
-	0x74, 0x02,				/*    jz    f                */
-	0x0f, 0x09,				/*    wbinvd                 */
-	0x24, 0x10,				/* f: andb  $0x10,al         */
-	0x66, 0x0f, 0x22, 0xc0			/*    movl  %eax,%cr0        */
-};
-static const unsigned char jump_to_bios [] =
+void machine_real_restart(unsigned int type)
 {
-	0xea, 0x00, 0x00, 0xff, 0xff		/*    ljmp  $0xffff,$0x0000  */
-};
+	void *restart_va;
+	unsigned long restart_pa;
+	void (*restart_lowmem)(unsigned int);
+	u64 *lowmem_gdt;
 
-/*
- * Switch to real mode and then execute the code
- * specified by the code and length parameters.
- * We assume that length will aways be less that 100!
- */
-void machine_real_restart(const unsigned char *code, int length)
-{
 	local_irq_disable();
 
 	/* Write zero to CMOS register number 0x0f, which the BIOS POST
@@ -384,41 +332,23 @@ void machine_real_restart(const unsigned char *code, int length)
 	   too. */
 	*((unsigned short *)0x472) = reboot_mode;
 
-	/* For the switch to real mode, copy some code to low memory.  It has
-	   to be in the first 64k because it is running in 16-bit mode, and it
-	   has to have the same physical and virtual address, because it turns
-	   off paging.  Copy it near the end of the first page, out of the way
-	   of BIOS variables. */
-	memcpy((void *)(0x1000 - sizeof(real_mode_switch) - 100),
-		real_mode_switch, sizeof (real_mode_switch));
-	memcpy((void *)(0x1000 - 100), code, length);
-
-	/* Set up the IDT for real mode. */
-	load_idt(&real_mode_idt);
-
-	/* Set up a GDT from which we can load segment descriptors for real
-	   mode.  The GDT is not used in real mode; it is just needed here to
-	   prepare the descriptors. */
-	load_gdt(&real_mode_gdt);
-
-	/* Load the data segment registers, and thus the descriptors ready for
-	   real mode.  The base address of each segment is 0x100, 16 times the
-	   selector value being loaded here.  This is so that the segment
-	   registers don't have to be reloaded after switching to real mode:
-	   the values are consistent for real mode operation already. */
-	__asm__ __volatile__ ("movl $0x0010,%%eax\n"
-				"\tmovl %%eax,%%ds\n"
-				"\tmovl %%eax,%%es\n"
-				"\tmovl %%eax,%%fs\n"
-				"\tmovl %%eax,%%gs\n"
-				"\tmovl %%eax,%%ss" : : : "eax");
-
-	/* Jump to the 16-bit code that we copied earlier.  It disables paging
-	   and the cache, switches to real mode, and jumps to the BIOS reset
-	   entry point. */
-	__asm__ __volatile__ ("ljmp $0x0008,%0"
-				:
-				: "i" ((void *)(0x1000 - sizeof (real_mode_switch) - 100)));
+	/* Patch the GDT in the low memory trampoline */
+	lowmem_gdt = TRAMPOLINE_SYM(machine_real_restart_gdt);
+
+	restart_va = TRAMPOLINE_SYM(machine_real_restart_asm);
+	restart_pa = virt_to_phys(restart_va);
+	restart_lowmem = (void (*)(unsigned int))restart_pa;
+
+	/* GDT[0]: GDT self-pointer */
+	lowmem_gdt[0] =
+		(u64)(sizeof(machine_real_restart_gdt) - 1) +
+		((u64)virt_to_phys(lowmem_gdt) << 16);
+	/* GDT[1]: 64K real mode code segment */
+	lowmem_gdt[1] =
+		GDT_ENTRY(0x009b, restart_pa, 0xffff);
+
+	/* Jump to the identity-mapped low memory code */
+	restart_lowmem(type);
 }
 #ifdef CONFIG_APM_MODULE
 EXPORT_SYMBOL(machine_real_restart);
@@ -573,7 +503,7 @@ static void native_machine_emergency_restart(void)
 
 #ifdef CONFIG_X86_32
 		case BOOT_BIOS:
-			machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
+			machine_real_restart(MRR_BIOS);
 
 			reboot_type = BOOT_KBD;
 			break;
diff --git a/arch/x86/kernel/reboot_32.S b/arch/x86/kernel/reboot_32.S
new file mode 100644
index 0000000..f242356
--- /dev/null
+++ b/arch/x86/kernel/reboot_32.S
@@ -0,0 +1,131 @@
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/segment.h>
+#include <asm/page_types.h>
+
+/*
+ * The following code and data reboots the machine by switching to real
+ * mode and jumping to the BIOS reset entry point, as if the CPU has
+ * really been reset.  The previous version asked the keyboard
+ * controller to pulse the CPU reset line, which is more thorough, but
+ * doesn't work with at least one type of 486 motherboard.  It is easy
+ * to stop this code working; hence the copious comments.
+ *
+ * This code is called with the restart type (0 = BIOS, 1 = APM) in %eax.
+ */
+	.section ".x86_trampoline","a"
+	.balign 16
+	.code32
+ENTRY(machine_real_restart_asm)
+r_base = .
+	/* Get our own relocated address */
+	call	1f
+1:	popl	%ebx
+	subl	$1b, %ebx
+
+	/* Patch post-real-mode segment jump */
+	movw	dispatch_table(%ebx,%ecx,2),%cx
+	movw	%cx, 101f(%ebx)
+	movw	%ax, 102f(%ebx)
+
+	/* Set up the IDT for real mode. */
+	lidtl	machine_real_restart_idt(%ebx)
+
+	/*
+	 * Set up a GDT from which we can load segment descriptors for real
+	 * mode.  The GDT is not used in real mode; it is just needed here to
+	 * prepare the descriptors.
+	 */
+	lgdtl	machine_real_restart_gdt(%ebx)
+
+	/*
+	 * Load the data segment registers with 16-bit compatible values
+	 */
+	movl	$16, %ecx
+	movl	%ecx, %ds
+	movl	%ecx, %es
+	movl	%ecx, %fs
+	movl	%ecx, %gs
+	movl	%ecx, %ss
+	ljmpl	$8, $1f - r_base
+
+/*
+ * This is 16-bit protected mode code to disable paging and the cache,
+ * switch to real mode and jump to the BIOS reset code.
+ *
+ * The instruction that switches to real mode by writing to CR0 must be
+ * followed immediately by a far jump instruction, which set CS to a
+ * valid value for real mode, and flushes the prefetch queue to avoid
+ * running instructions that have already been decoded in protected
+ * mode.
+ *
+ * Clears all the flags except ET, especially PG (paging), PE
+ * (protected-mode enable) and TS (task switch for coprocessor state
+ * save).  Flushes the TLB after paging has been disabled.  Sets CD and
+ * NW, to disable the cache on a 486, and invalidates the cache.  This
+ * is more like the state of a 486 after reset.  I don't know if
+ * something else should be done for other chips.
+ *
+ * More could be done here to set up the registers as if a CPU reset had
+ * occurred; hopefully real BIOSs don't assume much.  This is not the
+ * actual BIOS entry point, anyway (that is at 0xfffffff0).
+ *
+ * Most of this work is probably excessive, but it is what is tested.
+ */
+	.code16
+1:
+	xorl	%ecx, %ecx
+	movl	%cr0, %eax
+	andl	$0x00000011, %eax
+	orl	$0x60000000, %eax
+	movl	%eax, %cr0
+	movl	%ecx, %cr3
+	movl	%cr0, %edx
+	andl	$0x60000000, %edx	/* If no cache bits -> no wbinvd */
+	jz	2f
+	wbinvd
+2:
+	andb	$0x10, %al
+	movl	%eax, %cr0
+	.byte	0xea			/* ljmpw */
+101:	.word	0			/* Offset */
+102:	.word	0			/* Segment */
+
+bios:
+	ljmpw	$0xf000, $0xfff0
+
+apm:
+	movw	$0x1000, %ax
+	movw	%ax, %ss
+	movw	$0xf000, %sp
+	movw	$0x5307, %ax
+	movw	$0x0001, %bx
+	movw	$0x0003, %cx
+	int	$0x15
+
+END(machine_real_restart_asm)
+
+	.balign 16
+	/* These must match <asm/reboot.h */
+dispatch_table:
+	.word	bios - r_base
+	.word	apm - r_base
+END(dispatch_table)
+
+	.balign 16
+machine_real_restart_idt:
+	.word	0xffff		/* Length - real mode default value */
+	.long	0		/* Base - real mode default value */
+END(machine_real_restart_idt)
+
+	.balign 16
+ENTRY(machine_real_restart_gdt)
+	.quad	0		/* Self-pointer, filled in by PM code */
+	.quad	0		/* 16-bit code segment, filled in by PM code */
+	/*
+	 * 16-bit data segment with the selector value 16 = 0x10 and
+	 * base value 0x100; since this is consistent with real mode
+	 * semantics we don't have to reload the segments once CR0.PE = 0.
+	 */
+	.quad	GDT_ENTRY(0x0093, 0x100, 0xffff)
+END(machine_real_restart_gdt)

Re: [tip:x86/trampoline] x86, reboot: Move the real-mode reboot code to an assembly file

[Brian Gerst]

On Fri, Feb 18, 2011 at 12:20 AM, tip-bot for H. Peter Anvin
<hpa@linux.intel.com> wrote:
> Commit-ID:  3d35ac346e981162eeba391e496faceed4753e7b
> Gitweb:     http://git.kernel.org/tip/3d35ac346e981162eeba391e496faceed4753e7b
> Author:     H. Peter Anvin <hpa@linux.intel.com>
> AuthorDate: Mon, 14 Feb 2011 18:36:03 -0800
> Committer:  H. Peter Anvin <hpa@linux.intel.com>
> CommitDate: Thu, 17 Feb 2011 21:05:34 -0800
>
> x86, reboot: Move the real-mode reboot code to an assembly file
>
> Move the real-mode reboot code out to an assembly file (reboot_32.S)
> which is allocated using the common lowmem trampoline allocator.
>
> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
> LKML-Reference: <4D5DFBE4.7090104@intel.com>
> Cc: Stephen Rothwell <sfr@canb.auug.org.au>
> Cc: Rafael J. Wysocki <rjw@sisk.pl>
> Cc: Matthieu Castet <castet.matthieu@free.fr>
> ---
>  arch/x86/include/asm/reboot.h |    5 +-
>  arch/x86/kernel/Makefile      |    1 +
>  arch/x86/kernel/apm_32.c      |   12 +----
>  arch/x86/kernel/reboot.c      |  120 ++++++++-----------------------------
>  arch/x86/kernel/reboot_32.S   |  131 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 162 insertions(+), 107 deletions(-)
>
> diff --git a/arch/x86/include/asm/reboot.h b/arch/x86/include/asm/reboot.h
> index 562d4fd..3250e3d 100644
> --- a/arch/x86/include/asm/reboot.h
> +++ b/arch/x86/include/asm/reboot.h
> @@ -18,7 +18,10 @@ extern struct machine_ops machine_ops;
>
>  void native_machine_crash_shutdown(struct pt_regs *regs);
>  void native_machine_shutdown(void);
> -void machine_real_restart(const unsigned char *code, int length);
> +void machine_real_restart(unsigned int type);
> +/* These must match dispatch_table in reboot_32.S */
> +#define MRR_BIOS       0
> +#define MRR_APM                1
>
>  typedef void (*nmi_shootdown_cb)(int, struct die_args*);
>  void nmi_shootdown_cpus(nmi_shootdown_cb callback);
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 2e8ce0d..778c5b93 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -59,6 +59,7 @@ obj-$(CONFIG_STACKTRACE)      += stacktrace.o
>  obj-y                          += cpu/
>  obj-y                          += acpi/
>  obj-y                          += reboot.o
> +obj-$(CONFIG_X86_32)           += reboot_32.o
>  obj-$(CONFIG_MCA)              += mca_32.o
>  obj-$(CONFIG_X86_MSR)          += msr.o
>  obj-$(CONFIG_X86_CPUID)                += cpuid.o
> diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
> index 0e4f24c..b929108 100644
> --- a/arch/x86/kernel/apm_32.c
> +++ b/arch/x86/kernel/apm_32.c
> @@ -975,20 +975,10 @@ recalc:
>
>  static void apm_power_off(void)
>  {
> -       unsigned char po_bios_call[] = {
> -               0xb8, 0x00, 0x10,       /* movw  $0x1000,ax  */
> -               0x8e, 0xd0,             /* movw  ax,ss       */
> -               0xbc, 0x00, 0xf0,       /* movw  $0xf000,sp  */
> -               0xb8, 0x07, 0x53,       /* movw  $0x5307,ax  */
> -               0xbb, 0x01, 0x00,       /* movw  $0x0001,bx  */
> -               0xb9, 0x03, 0x00,       /* movw  $0x0003,cx  */
> -               0xcd, 0x15              /* int   $0x15       */
> -       };
> -
>        /* Some bioses don't like being called from CPU != 0 */
>        if (apm_info.realmode_power_off) {
>                set_cpus_allowed_ptr(current, cpumask_of(0));
> -               machine_real_restart(po_bios_call, sizeof(po_bios_call));
> +               machine_real_restart(MRR_APM);
>        } else {
>                (void)set_system_power_state(APM_STATE_OFF);
>        }
> diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
> index fc7aae1..10c6619 100644
> --- a/arch/x86/kernel/reboot.c
> +++ b/arch/x86/kernel/reboot.c
> @@ -295,68 +295,16 @@ static int __init reboot_init(void)
>  }
>  core_initcall(reboot_init);
>
> -/* The following code and data reboots the machine by switching to real
> -   mode and jumping to the BIOS reset entry point, as if the CPU has
> -   really been reset.  The previous version asked the keyboard
> -   controller to pulse the CPU reset line, which is more thorough, but
> -   doesn't work with at least one type of 486 motherboard.  It is easy
> -   to stop this code working; hence the copious comments. */
> -static const unsigned long long
> -real_mode_gdt_entries [3] =
> -{
> -       0x0000000000000000ULL,  /* Null descriptor */
> -       0x00009b000000ffffULL,  /* 16-bit real-mode 64k code at 0x00000000 */
> -       0x000093000100ffffULL   /* 16-bit real-mode 64k data at 0x00000100 */
> -};
> +extern const unsigned char machine_real_restart_asm[];
> +extern const u64 machine_real_restart_gdt[3];
>
> -static const struct desc_ptr
> -real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, (long)real_mode_gdt_entries },
> -real_mode_idt = { 0x3ff, 0 };
> -
> -/* This is 16-bit protected mode code to disable paging and the cache,
> -   switch to real mode and jump to the BIOS reset code.
> -
> -   The instruction that switches to real mode by writing to CR0 must be
> -   followed immediately by a far jump instruction, which set CS to a
> -   valid value for real mode, and flushes the prefetch queue to avoid
> -   running instructions that have already been decoded in protected
> -   mode.
> -
> -   Clears all the flags except ET, especially PG (paging), PE
> -   (protected-mode enable) and TS (task switch for coprocessor state
> -   save).  Flushes the TLB after paging has been disabled.  Sets CD and
> -   NW, to disable the cache on a 486, and invalidates the cache.  This
> -   is more like the state of a 486 after reset.  I don't know if
> -   something else should be done for other chips.
> -
> -   More could be done here to set up the registers as if a CPU reset had
> -   occurred; hopefully real BIOSs don't assume much. */
> -static const unsigned char real_mode_switch [] =
> -{
> -       0x66, 0x0f, 0x20, 0xc0,                 /*    movl  %cr0,%eax        */
> -       0x66, 0x83, 0xe0, 0x11,                 /*    andl  $0x00000011,%eax */
> -       0x66, 0x0d, 0x00, 0x00, 0x00, 0x60,     /*    orl   $0x60000000,%eax */
> -       0x66, 0x0f, 0x22, 0xc0,                 /*    movl  %eax,%cr0        */
> -       0x66, 0x0f, 0x22, 0xd8,                 /*    movl  %eax,%cr3        */
> -       0x66, 0x0f, 0x20, 0xc3,                 /*    movl  %cr0,%ebx        */
> -       0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60,       /*    andl  $0x60000000,%ebx */
> -       0x74, 0x02,                             /*    jz    f                */
> -       0x0f, 0x09,                             /*    wbinvd                 */
> -       0x24, 0x10,                             /* f: andb  $0x10,al         */
> -       0x66, 0x0f, 0x22, 0xc0                  /*    movl  %eax,%cr0        */
> -};
> -static const unsigned char jump_to_bios [] =
> +void machine_real_restart(unsigned int type)
>  {
> -       0xea, 0x00, 0x00, 0xff, 0xff            /*    ljmp  $0xffff,$0x0000  */
> -};
> +       void *restart_va;
> +       unsigned long restart_pa;
> +       void (*restart_lowmem)(unsigned int);
> +       u64 *lowmem_gdt;
>
> -/*
> - * Switch to real mode and then execute the code
> - * specified by the code and length parameters.
> - * We assume that length will aways be less that 100!
> - */
> -void machine_real_restart(const unsigned char *code, int length)
> -{
>        local_irq_disable();
>
>        /* Write zero to CMOS register number 0x0f, which the BIOS POST
> @@ -384,41 +332,23 @@ void machine_real_restart(const unsigned char *code, int length)
>           too. */
>        *((unsigned short *)0x472) = reboot_mode;
>
> -       /* For the switch to real mode, copy some code to low memory.  It has
> -          to be in the first 64k because it is running in 16-bit mode, and it
> -          has to have the same physical and virtual address, because it turns
> -          off paging.  Copy it near the end of the first page, out of the way
> -          of BIOS variables. */
> -       memcpy((void *)(0x1000 - sizeof(real_mode_switch) - 100),
> -               real_mode_switch, sizeof (real_mode_switch));
> -       memcpy((void *)(0x1000 - 100), code, length);
> -
> -       /* Set up the IDT for real mode. */
> -       load_idt(&real_mode_idt);
> -
> -       /* Set up a GDT from which we can load segment descriptors for real
> -          mode.  The GDT is not used in real mode; it is just needed here to
> -          prepare the descriptors. */
> -       load_gdt(&real_mode_gdt);
> -
> -       /* Load the data segment registers, and thus the descriptors ready for
> -          real mode.  The base address of each segment is 0x100, 16 times the
> -          selector value being loaded here.  This is so that the segment
> -          registers don't have to be reloaded after switching to real mode:
> -          the values are consistent for real mode operation already. */
> -       __asm__ __volatile__ ("movl $0x0010,%%eax\n"
> -                               "\tmovl %%eax,%%ds\n"
> -                               "\tmovl %%eax,%%es\n"
> -                               "\tmovl %%eax,%%fs\n"
> -                               "\tmovl %%eax,%%gs\n"
> -                               "\tmovl %%eax,%%ss" : : : "eax");
> -
> -       /* Jump to the 16-bit code that we copied earlier.  It disables paging
> -          and the cache, switches to real mode, and jumps to the BIOS reset
> -          entry point. */
> -       __asm__ __volatile__ ("ljmp $0x0008,%0"
> -                               :
> -                               : "i" ((void *)(0x1000 - sizeof (real_mode_switch) - 100)));
> +       /* Patch the GDT in the low memory trampoline */
> +       lowmem_gdt = TRAMPOLINE_SYM(machine_real_restart_gdt);
> +
> +       restart_va = TRAMPOLINE_SYM(machine_real_restart_asm);
> +       restart_pa = virt_to_phys(restart_va);
> +       restart_lowmem = (void (*)(unsigned int))restart_pa;
> +
> +       /* GDT[0]: GDT self-pointer */
> +       lowmem_gdt[0] =
> +               (u64)(sizeof(machine_real_restart_gdt) - 1) +
> +               ((u64)virt_to_phys(lowmem_gdt) << 16);
> +       /* GDT[1]: 64K real mode code segment */
> +       lowmem_gdt[1] =
> +               GDT_ENTRY(0x009b, restart_pa, 0xffff);
> +
> +       /* Jump to the identity-mapped low memory code */
> +       restart_lowmem(type);
>  }
>  #ifdef CONFIG_APM_MODULE
>  EXPORT_SYMBOL(machine_real_restart);
> @@ -573,7 +503,7 @@ static void native_machine_emergency_restart(void)
>
>  #ifdef CONFIG_X86_32
>                case BOOT_BIOS:
> -                       machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
> +                       machine_real_restart(MRR_BIOS);
>
>                        reboot_type = BOOT_KBD;
>                        break;
> diff --git a/arch/x86/kernel/reboot_32.S b/arch/x86/kernel/reboot_32.S
> new file mode 100644
> index 0000000..f242356
> --- /dev/null
> +++ b/arch/x86/kernel/reboot_32.S
> @@ -0,0 +1,131 @@
> +#include <linux/linkage.h>
> +#include <linux/init.h>
> +#include <asm/segment.h>
> +#include <asm/page_types.h>
> +
> +/*
> + * The following code and data reboots the machine by switching to real
> + * mode and jumping to the BIOS reset entry point, as if the CPU has
> + * really been reset.  The previous version asked the keyboard
> + * controller to pulse the CPU reset line, which is more thorough, but
> + * doesn't work with at least one type of 486 motherboard.  It is easy
> + * to stop this code working; hence the copious comments.
> + *
> + * This code is called with the restart type (0 = BIOS, 1 = APM) in %eax.
> + */
> +       .section ".x86_trampoline","a"
> +       .balign 16
> +       .code32
> +ENTRY(machine_real_restart_asm)
> +r_base = .
> +       /* Get our own relocated address */
> +       call    1f
> +1:     popl    %ebx
> +       subl    $1b, %ebx
> +
> +       /* Patch post-real-mode segment jump */
> +       movw    dispatch_table(%ebx,%ecx,2),%cx
> +       movw    %cx, 101f(%ebx)
> +       movw    %ax, 102f(%ebx)

This looks wrong.  The type parameter is in %eax, not %ecx, and this
code is expecting %eax to be a segment.

--
Brian Gerst

Re: [tip:x86/trampoline] x86, reboot: Move the real-mode reboot code to an assembly file

[H. Peter Anvin]

On 02/18/2011 04:31 AM, Brian Gerst wrote:
>> +
>> +       /* Patch post-real-mode segment jump */
>> +       movw    dispatch_table(%ebx,%ecx,2),%cx
>> +       movw    %cx, 101f(%ebx)
>> +       movw    %ax, 102f(%ebx)
> 
> This looks wrong.  The type parameter is in %eax, not %ecx, and this
> code is expecting %eax to be a segment.
> 

You're quite right.  I decided to make a change, changed all the
invocations, and forgot to change the actual code.  D'oh!

	-hpa

[tip:x86/trampoline] x86, reboot: Fix the use of passed arguments in 32-bit BIOS reboot

[tip-bot for H. Peter Anvin]

Commit-ID:  ee1b06ea6aed979da3b4e6b6ffea98ad55a3c5c1
Gitweb:     http://git.kernel.org/tip/ee1b06ea6aed979da3b4e6b6ffea98ad55a3c5c1
Author:     H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Fri, 18 Feb 2011 15:47:42 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Fri, 18 Feb 2011 15:47:42 -0800

x86, reboot: Fix the use of passed arguments in 32-bit BIOS reboot

The initial version of this patch had %eax being a segment and %ecx
being the mode.  I had changed the interfaces, but not the actual
implementation!

Reported-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <AANLkTikxqk=HEw9R-Du=v-1ti1HDGAY9vaNUep2XARaz@mail.gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
---
 arch/x86/kernel/reboot_32.S |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/reboot_32.S b/arch/x86/kernel/reboot_32.S
index f242356..29092b3 100644
--- a/arch/x86/kernel/reboot_32.S
+++ b/arch/x86/kernel/reboot_32.S
@@ -23,10 +23,14 @@ r_base = .
 1:	popl	%ebx
 	subl	$1b, %ebx
 
+	/* Compute the equivalent real-mode segment */
+	movl	%ebx, %ecx
+	shrl	$4, %ecx
+	
 	/* Patch post-real-mode segment jump */
-	movw	dispatch_table(%ebx,%ecx,2),%cx
-	movw	%cx, 101f(%ebx)
-	movw	%ax, 102f(%ebx)
+	movw	dispatch_table(%ebx,%eax,2),%ax
+	movw	%ax, 101f(%ebx)
+	movw	%cx, 102f(%ebx)
 
 	/* Set up the IDT for real mode. */
 	lidtl	machine_real_restart_idt(%ebx)

Re: [tip:x86/trampoline] x86, reboot: Move the real-mode reboot code to an assembly file

[Alexey Zaytsev]

On Fri, Feb 18, 2011 at 08:20, tip-bot for H. Peter Anvin
<hpa@linux.intel.com> wrote:
> Commit-ID:  3d35ac346e981162eeba391e496faceed4753e7b
> Gitweb:     http://git.kernel.org/tip/3d35ac346e981162eeba391e496faceed4753e7b
> Author:     H. Peter Anvin <hpa@linux.intel.com>
> AuthorDate: Mon, 14 Feb 2011 18:36:03 -0800
> Committer:  H. Peter Anvin <hpa@linux.intel.com>
> CommitDate: Thu, 17 Feb 2011 21:05:34 -0800
>
> x86, reboot: Move the real-mode reboot code to an assembly file
>
> Move the real-mode reboot code out to an assembly file (reboot_32.S)
> which is allocated using the common lowmem trampoline allocator.
>

Hi. This one causes problems on at least a couple HP Compaq laptops:
https://bugzilla.kernel.org/show_bug.cgi?id=33302

Re: [tip:x86/trampoline] x86, reboot: Move the real-mode reboot code to an assembly file

[H. Peter Anvin]

On 04/29/2011 08:16 AM, Alexey Zaytsev wrote:
> On Fri, Feb 18, 2011 at 08:20, tip-bot for H. Peter Anvin
> <hpa@linux.intel.com> wrote:
>> Commit-ID:  3d35ac346e981162eeba391e496faceed4753e7b
>> Gitweb:     http://git.kernel.org/tip/3d35ac346e981162eeba391e496faceed4753e7b
>> Author:     H. Peter Anvin <hpa@linux.intel.com>
>> AuthorDate: Mon, 14 Feb 2011 18:36:03 -0800
>> Committer:  H. Peter Anvin <hpa@linux.intel.com>
>> CommitDate: Thu, 17 Feb 2011 21:05:34 -0800
>>
>> x86, reboot: Move the real-mode reboot code to an assembly file
>>
>> Move the real-mode reboot code out to an assembly file (reboot_32.S)
>> which is allocated using the common lowmem trampoline allocator.
>>
> 
> Hi. This one causes problems on at least a couple HP Compaq laptops:
> https://bugzilla.kernel.org/show_bug.cgi?id=33302
> 

Saw that... trying to figure out how to reproduce it.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.