Commit 11d4c3f9 authored by H. Peter Anvin's avatar H. Peter Anvin Committed by H. Peter Anvin
Browse files

x86-32: Make sure the stack is set up before we use it

Since checkin ebba638a

 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: default avatarMatthieu Castet <castet.matthieu@free.fr>
LKML-Reference: <4D41E86D.8060205@free.fr>
Tested-by: default avatarKees Cook <kees.cook@canonical.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent f7448548
......@@ -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);
......
......@@ -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());
......
......@@ -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"
......
......@@ -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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