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Date: Sat, 5 Feb 2011 06:31:02 GMT
From: "tip-bot for H. Peter Anvin" <hpa@...ux.intel.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
castet.matthieu@...e.fr, kees.cook@...onical.com,
tglx@...utronix.de, hpa@...ux.intel.com
Subject: [tip:x86/urgent] x86-32: Make sure the stack is set up before we use it
Commit-ID: 11d4c3f9b671720e80353dd7e433ff2bf65e9500
Gitweb: http://git.kernel.org/tip/11d4c3f9b671720e80353dd7e433ff2bf65e9500
Author: H. Peter Anvin <hpa@...ux.intel.com>
AuthorDate: Fri, 4 Feb 2011 16:14:11 -0800
Committer: H. Peter Anvin <hpa@...or.com>
CommitDate: Fri, 4 Feb 2011 22:27:28 -0800
x86-32: Make sure the stack is set up before we use it
Since checkin ebba638ae723d8a8fc2f7abce5ec18b688b791d7 we call
verify_cpu even in 32-bit mode. Unfortunately, calling a function
means using the stack, and the stack pointer was not initialized in
the 32-bit setup code! This code initializes the stack pointer, and
simplifies the interface slightly since it is easier to rely on just a
pointer value rather than a descriptor; we need to have different
values for the segment register anyway.
This retains start_stack as a virtual address, even though a physical
address would be more convenient for 32 bits; the 64-bit code wants
the other way around...
Reported-by: Matthieu Castet <castet.matthieu@...e.fr>
LKML-Reference: <4D41E86D.8060205@...e.fr>
Tested-by: Kees Cook <kees.cook@...onical.com>
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
---
arch/x86/include/asm/smp.h | 5 +----
arch/x86/kernel/acpi/sleep.c | 2 +-
arch/x86/kernel/head_32.S | 30 +++++++++++++-----------------
arch/x86/kernel/smpboot.c | 4 ++--
4 files changed, 17 insertions(+), 24 deletions(-)
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 4c2f63c..1f46951 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -40,10 +40,7 @@ DECLARE_EARLY_PER_CPU(u16, x86_cpu_to_apicid);
DECLARE_EARLY_PER_CPU(u16, x86_bios_cpu_apicid);
/* Static state in head.S used to set up a CPU */
-extern struct {
- void *sp;
- unsigned short ss;
-} stack_start;
+extern unsigned long stack_start; /* Initial stack pointer address */
struct smp_ops {
void (*smp_prepare_boot_cpu)(void);
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 69fd72a..4d9ebba 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -100,7 +100,7 @@ int acpi_save_state_mem(void)
#else /* CONFIG_64BIT */
header->trampoline_segment = setup_trampoline() >> 4;
#ifdef CONFIG_SMP
- stack_start.sp = temp_stack + sizeof(temp_stack);
+ stack_start = (unsigned long)temp_stack + sizeof(temp_stack);
early_gdt_descr.address =
(unsigned long)get_cpu_gdt_table(smp_processor_id());
initial_gs = per_cpu_offset(smp_processor_id());
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index fc293dc..767d6c4 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -85,6 +85,8 @@ RESERVE_BRK(pagetables, INIT_MAP_SIZE)
*/
__HEAD
ENTRY(startup_32)
+ movl pa(stack_start),%ecx
+
/* test KEEP_SEGMENTS flag to see if the bootloader is asking
us to not reload segments */
testb $(1<<6), BP_loadflags(%esi)
@@ -99,7 +101,9 @@ ENTRY(startup_32)
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
+ movl %eax,%ss
2:
+ leal -__PAGE_OFFSET(%ecx),%esp
/*
* Clear BSS first so that there are no surprises...
@@ -145,8 +149,6 @@ ENTRY(startup_32)
* _brk_end is set up to point to the first "safe" location.
* Mappings are created both at virtual address 0 (identity mapping)
* and PAGE_OFFSET for up to _end.
- *
- * Note that the stack is not yet set up!
*/
#ifdef CONFIG_X86_PAE
@@ -282,6 +284,9 @@ ENTRY(startup_32_smp)
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
+ movl pa(stack_start),%ecx
+ movl %eax,%ss
+ leal -__PAGE_OFFSET(%ecx),%esp
#endif /* CONFIG_SMP */
default_entry:
@@ -347,8 +352,8 @@ default_entry:
movl %eax,%cr0 /* ..and set paging (PG) bit */
ljmp $__BOOT_CS,$1f /* Clear prefetch and normalize %eip */
1:
- /* Set up the stack pointer */
- lss stack_start,%esp
+ /* Shift the stack pointer to a virtual address */
+ addl $__PAGE_OFFSET, %esp
/*
* Initialize eflags. Some BIOS's leave bits like NT set. This would
@@ -360,9 +365,7 @@ default_entry:
#ifdef CONFIG_SMP
cmpb $0, ready
- jz 1f /* Initial CPU cleans BSS */
- jmp checkCPUtype
-1:
+ jnz checkCPUtype
#endif /* CONFIG_SMP */
/*
@@ -470,14 +473,7 @@ is386: movl $2,%ecx # set MP
cld # gcc2 wants the direction flag cleared at all times
pushl $0 # fake return address for unwinder
-#ifdef CONFIG_SMP
- movb ready, %cl
movb $1, ready
- cmpb $0,%cl # the first CPU calls start_kernel
- je 1f
- movl (stack_start), %esp
-1:
-#endif /* CONFIG_SMP */
jmp *(initial_code)
/*
@@ -670,15 +666,15 @@ ENTRY(initial_page_table)
#endif
.data
+.balign 4
ENTRY(stack_start)
.long init_thread_union+THREAD_SIZE
- .long __BOOT_DS
-
-ready: .byte 0
early_recursion_flag:
.long 0
+ready: .byte 0
+
int_msg:
.asciz "Unknown interrupt or fault at: %p %p %p\n"
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 0cbe8c0..03273b6 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -638,7 +638,7 @@ wakeup_secondary_cpu_via_init(int phys_apicid, unsigned long start_eip)
* target processor state.
*/
startup_ipi_hook(phys_apicid, (unsigned long) start_secondary,
- (unsigned long)stack_start.sp);
+ stack_start);
/*
* Run STARTUP IPI loop.
@@ -785,7 +785,7 @@ do_rest:
#endif
early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
initial_code = (unsigned long)start_secondary;
- stack_start.sp = (void *) c_idle.idle->thread.sp;
+ stack_start = c_idle.idle->thread.sp;
/* start_ip had better be page-aligned! */
start_ip = setup_trampoline();
--
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