kernel_optimize_test/arch/mips/kernel/head.S
David Daney 484889fc85 MIPS: Avoid clobbering struct pt_regs in kthreads
The resume() implementation octeon_switch.S examines the saved cp0_status
register.  We were clobbering the entire pt_regs structure in kernel
threads leading to random crashes.

When switching away from a kernel thread, the saved cp0_status is examined
and if bit 30 is set it is cleared and the CP2 state saved into the pt_regs
structure.  Since the kernel thread stack overlaid the pt_regs structure
this resulted in a corrupt stack.  When the kthread with the corrupt stack
was resumed, it could crash if it used any of the data in the stack that was
clobbered.

We fix it by moving the kernel thread stack down so it doesn't overlay
pt_regs.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-08-03 17:52:41 +01:00

232 lines
5.9 KiB
ArmAsm

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1994, 1995 Waldorf Electronics
* Written by Ralf Baechle and Andreas Busse
* Copyright (C) 1994 - 99, 2003, 06 Ralf Baechle
* Copyright (C) 1996 Paul M. Antoine
* Modified for DECStation and hence R3000 support by Paul M. Antoine
* Further modifications by David S. Miller and Harald Koerfgen
* Copyright (C) 1999 Silicon Graphics, Inc.
* Kevin Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
*/
#include <linux/init.h>
#include <linux/threads.h>
#include <asm/addrspace.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/irqflags.h>
#include <asm/regdef.h>
#include <asm/page.h>
#include <asm/pgtable-bits.h>
#include <asm/mipsregs.h>
#include <asm/stackframe.h>
#include <kernel-entry-init.h>
/*
* inputs are the text nasid in t1, data nasid in t2.
*/
.macro MAPPED_KERNEL_SETUP_TLB
#ifdef CONFIG_MAPPED_KERNEL
/*
* This needs to read the nasid - assume 0 for now.
* Drop in 0xffffffffc0000000 in tlbhi, 0+VG in tlblo_0,
* 0+DVG in tlblo_1.
*/
dli t0, 0xffffffffc0000000
dmtc0 t0, CP0_ENTRYHI
li t0, 0x1c000 # Offset of text into node memory
dsll t1, NASID_SHFT # Shift text nasid into place
dsll t2, NASID_SHFT # Same for data nasid
or t1, t1, t0 # Physical load address of kernel text
or t2, t2, t0 # Physical load address of kernel data
dsrl t1, 12 # 4K pfn
dsrl t2, 12 # 4K pfn
dsll t1, 6 # Get pfn into place
dsll t2, 6 # Get pfn into place
li t0, ((_PAGE_GLOBAL|_PAGE_VALID| _CACHE_CACHABLE_COW) >> 6)
or t0, t0, t1
mtc0 t0, CP0_ENTRYLO0 # physaddr, VG, cach exlwr
li t0, ((_PAGE_GLOBAL|_PAGE_VALID| _PAGE_DIRTY|_CACHE_CACHABLE_COW) >> 6)
or t0, t0, t2
mtc0 t0, CP0_ENTRYLO1 # physaddr, DVG, cach exlwr
li t0, 0x1ffe000 # MAPPED_KERN_TLBMASK, TLBPGMASK_16M
mtc0 t0, CP0_PAGEMASK
li t0, 0 # KMAP_INX
mtc0 t0, CP0_INDEX
li t0, 1
mtc0 t0, CP0_WIRED
tlbwi
#else
mtc0 zero, CP0_WIRED
#endif
.endm
/*
* For the moment disable interrupts, mark the kernel mode and
* set ST0_KX so that the CPU does not spit fire when using
* 64-bit addresses. A full initialization of the CPU's status
* register is done later in per_cpu_trap_init().
*/
.macro setup_c0_status set clr
.set push
#ifdef CONFIG_MIPS_MT_SMTC
/*
* For SMTC, we need to set privilege and disable interrupts only for
* the current TC, using the TCStatus register.
*/
mfc0 t0, CP0_TCSTATUS
/* Fortunately CU 0 is in the same place in both registers */
/* Set TCU0, TMX, TKSU (for later inversion) and IXMT */
li t1, ST0_CU0 | 0x08001c00
or t0, t1
/* Clear TKSU, leave IXMT */
xori t0, 0x00001800
mtc0 t0, CP0_TCSTATUS
_ehb
/* We need to leave the global IE bit set, but clear EXL...*/
mfc0 t0, CP0_STATUS
or t0, ST0_CU0 | ST0_EXL | ST0_ERL | \set | \clr
xor t0, ST0_EXL | ST0_ERL | \clr
mtc0 t0, CP0_STATUS
#else
mfc0 t0, CP0_STATUS
or t0, ST0_CU0|\set|0x1f|\clr
xor t0, 0x1f|\clr
mtc0 t0, CP0_STATUS
.set noreorder
sll zero,3 # ehb
#endif
.set pop
.endm
.macro setup_c0_status_pri
#ifdef CONFIG_64BIT
setup_c0_status ST0_KX 0
#else
setup_c0_status 0 0
#endif
.endm
.macro setup_c0_status_sec
#ifdef CONFIG_64BIT
setup_c0_status ST0_KX ST0_BEV
#else
setup_c0_status 0 ST0_BEV
#endif
.endm
#ifndef CONFIG_NO_EXCEPT_FILL
/*
* Reserved space for exception handlers.
* Necessary for machines which link their kernels at KSEG0.
*/
.fill 0x400
#endif
EXPORT(_stext)
#ifdef CONFIG_BOOT_RAW
/*
* Give us a fighting chance of running if execution beings at the
* kernel load address. This is needed because this platform does
* not have a ELF loader yet.
*/
FEXPORT(__kernel_entry)
j kernel_entry
#endif
__REF
NESTED(kernel_entry, 16, sp) # kernel entry point
kernel_entry_setup # cpu specific setup
setup_c0_status_pri
/* We might not get launched at the address the kernel is linked to,
so we jump there. */
PTR_LA t0, 0f
jr t0
0:
#ifdef CONFIG_MIPS_MT_SMTC
/*
* In SMTC kernel, "CLI" is thread-specific, in TCStatus.
* We still need to enable interrupts globally in Status,
* and clear EXL/ERL.
*
* TCContext is used to track interrupt levels under
* service in SMTC kernel. Clear for boot TC before
* allowing any interrupts.
*/
mtc0 zero, CP0_TCCONTEXT
mfc0 t0, CP0_STATUS
ori t0, t0, 0xff1f
xori t0, t0, 0x001e
mtc0 t0, CP0_STATUS
#endif /* CONFIG_MIPS_MT_SMTC */
PTR_LA t0, __bss_start # clear .bss
LONG_S zero, (t0)
PTR_LA t1, __bss_stop - LONGSIZE
1:
PTR_ADDIU t0, LONGSIZE
LONG_S zero, (t0)
bne t0, t1, 1b
LONG_S a0, fw_arg0 # firmware arguments
LONG_S a1, fw_arg1
LONG_S a2, fw_arg2
LONG_S a3, fw_arg3
MTC0 zero, CP0_CONTEXT # clear context register
PTR_LA $28, init_thread_union
/* Set the SP after an empty pt_regs. */
PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE
PTR_ADDU sp, $28
set_saved_sp sp, t0, t1
PTR_SUBU sp, 4 * SZREG # init stack pointer
j start_kernel
END(kernel_entry)
__CPUINIT
#ifdef CONFIG_SMP
/*
* SMP slave cpus entry point. Board specific code for bootstrap calls this
* function after setting up the stack and gp registers.
*/
NESTED(smp_bootstrap, 16, sp)
#ifdef CONFIG_MIPS_MT_SMTC
/*
* Read-modify-writes of Status must be atomic, and this
* is one case where CLI is invoked without EXL being
* necessarily set. The CLI and setup_c0_status will
* in fact be redundant for all but the first TC of
* each VPE being booted.
*/
DMT 10 # dmt t2 /* t0, t1 are used by CLI and setup_c0_status() */
jal mips_ihb
#endif /* CONFIG_MIPS_MT_SMTC */
setup_c0_status_sec
smp_slave_setup
#ifdef CONFIG_MIPS_MT_SMTC
andi t2, t2, VPECONTROL_TE
beqz t2, 2f
EMT # emt
2:
#endif /* CONFIG_MIPS_MT_SMTC */
j start_secondary
END(smp_bootstrap)
#endif /* CONFIG_SMP */
__FINIT