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alistair23-linux/arch/microblaze/kernel/entry.S
Jamie Garside c2219eda54 microblaze: Fix syscall error recovery for invalid syscall IDs 
This patch fixes two bugs in the Microblaze syscall trap handler when an invalid
syscall ID is used.

First, the range check on line 351 only checks for syscall IDs greater than
__NR_syscalls. A negative syscall ID (either passed to `syscall()` or as returned
by `do_syscall_trace_enter()` on error) will still satisfy this test and cause
the Linux kernel to access an invalid memory location and cause a kernel oops.
This has been fixed by also checking for r12 < 0.

Secondly, the current error recovery at line 378 returns using the wrong register
(r15 instead of r14) and does not restore the previous stack state. This has been
fixed by invoking `ret_from_trap` on error, setting r3 to `-ENOSYS`, similar to
what would happen when calling a valid syscall.

Signed-off-by: Jamie Garside <jamie.garside@york.ac.uk>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
2015-03-04 15:12:27 +01:00

1006 lines
28 KiB
ArmAsm
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/*
* Low-level system-call handling, trap handlers and context-switching
*
* Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2008-2009 PetaLogix
* Copyright (C) 2003 John Williams <jwilliams@itee.uq.edu.au>
* Copyright (C) 2001,2002 NEC Corporation
* Copyright (C) 2001,2002 Miles Bader <miles@gnu.org>
*
* 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.
*
* Written by Miles Bader <miles@gnu.org>
* Heavily modified by John Williams for Microblaze
*/
#include <linux/sys.h>
#include <linux/linkage.h>
#include <asm/entry.h>
#include <asm/current.h>
#include <asm/processor.h>
#include <asm/exceptions.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/page.h>
#include <asm/unistd.h>
#include <linux/errno.h>
#include <asm/signal.h>
#undef DEBUG
#ifdef DEBUG
/* Create space for syscalls counting. */
.section .data
.global syscall_debug_table
.align 4
syscall_debug_table:
.space (__NR_syscalls * 4)
#endif /* DEBUG */
#define C_ENTRY(name) .globl name; .align 4; name
/*
* Various ways of setting and clearing BIP in flags reg.
* This is mucky, but necessary using microblaze version that
* allows msr ops to write to BIP
*/
#if CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR
.macro clear_bip
msrclr r0, MSR_BIP
.endm
.macro set_bip
msrset r0, MSR_BIP
.endm
.macro clear_eip
msrclr r0, MSR_EIP
.endm
.macro set_ee
msrset r0, MSR_EE
.endm
.macro disable_irq
msrclr r0, MSR_IE
.endm
.macro enable_irq
msrset r0, MSR_IE
.endm
.macro set_ums
msrset r0, MSR_UMS
msrclr r0, MSR_VMS
.endm
.macro set_vms
msrclr r0, MSR_UMS
msrset r0, MSR_VMS
.endm
.macro clear_ums
msrclr r0, MSR_UMS
.endm
.macro clear_vms_ums
msrclr r0, MSR_VMS | MSR_UMS
.endm
#else
.macro clear_bip
mfs r11, rmsr
andi r11, r11, ~MSR_BIP
mts rmsr, r11
.endm
.macro set_bip
mfs r11, rmsr
ori r11, r11, MSR_BIP
mts rmsr, r11
.endm
.macro clear_eip
mfs r11, rmsr
andi r11, r11, ~MSR_EIP
mts rmsr, r11
.endm
.macro set_ee
mfs r11, rmsr
ori r11, r11, MSR_EE
mts rmsr, r11
.endm
.macro disable_irq
mfs r11, rmsr
andi r11, r11, ~MSR_IE
mts rmsr, r11
.endm
.macro enable_irq
mfs r11, rmsr
ori r11, r11, MSR_IE
mts rmsr, r11
.endm
.macro set_ums
mfs r11, rmsr
ori r11, r11, MSR_VMS
andni r11, r11, MSR_UMS
mts rmsr, r11
.endm
.macro set_vms
mfs r11, rmsr
ori r11, r11, MSR_VMS
andni r11, r11, MSR_UMS
mts rmsr, r11
.endm
.macro clear_ums
mfs r11, rmsr
andni r11, r11, MSR_UMS
mts rmsr,r11
.endm
.macro clear_vms_ums
mfs r11, rmsr
andni r11, r11, (MSR_VMS|MSR_UMS)
mts rmsr,r11
.endm
#endif
/* Define how to call high-level functions. With MMU, virtual mode must be
* enabled when calling the high-level function. Clobbers R11.
* VM_ON, VM_OFF, DO_JUMP_BIPCLR, DO_CALL
*/
/* turn on virtual protected mode save */
#define VM_ON \
set_ums; \
rted r0, 2f; \
nop; \
2:
/* turn off virtual protected mode save and user mode save*/
#define VM_OFF \
clear_vms_ums; \
rted r0, TOPHYS(1f); \
nop; \
1:
#define SAVE_REGS \
swi r2, r1, PT_R2; /* Save SDA */ \
swi r3, r1, PT_R3; \
swi r4, r1, PT_R4; \
swi r5, r1, PT_R5; \
swi r6, r1, PT_R6; \
swi r7, r1, PT_R7; \
swi r8, r1, PT_R8; \
swi r9, r1, PT_R9; \
swi r10, r1, PT_R10; \
swi r11, r1, PT_R11; /* save clobbered regs after rval */\
swi r12, r1, PT_R12; \
swi r13, r1, PT_R13; /* Save SDA2 */ \
swi r14, r1, PT_PC; /* PC, before IRQ/trap */ \
swi r15, r1, PT_R15; /* Save LP */ \
swi r16, r1, PT_R16; \
swi r17, r1, PT_R17; \
swi r18, r1, PT_R18; /* Save asm scratch reg */ \
swi r19, r1, PT_R19; \
swi r20, r1, PT_R20; \
swi r21, r1, PT_R21; \
swi r22, r1, PT_R22; \
swi r23, r1, PT_R23; \
swi r24, r1, PT_R24; \
swi r25, r1, PT_R25; \
swi r26, r1, PT_R26; \
swi r27, r1, PT_R27; \
swi r28, r1, PT_R28; \
swi r29, r1, PT_R29; \
swi r30, r1, PT_R30; \
swi r31, r1, PT_R31; /* Save current task reg */ \
mfs r11, rmsr; /* save MSR */ \
swi r11, r1, PT_MSR;
#define RESTORE_REGS \
lwi r11, r1, PT_MSR; \
mts rmsr , r11; \
lwi r2, r1, PT_R2; /* restore SDA */ \
lwi r3, r1, PT_R3; \
lwi r4, r1, PT_R4; \
lwi r5, r1, PT_R5; \
lwi r6, r1, PT_R6; \
lwi r7, r1, PT_R7; \
lwi r8, r1, PT_R8; \
lwi r9, r1, PT_R9; \
lwi r10, r1, PT_R10; \
lwi r11, r1, PT_R11; /* restore clobbered regs after rval */\
lwi r12, r1, PT_R12; \
lwi r13, r1, PT_R13; /* restore SDA2 */ \
lwi r14, r1, PT_PC; /* RESTORE_LINK PC, before IRQ/trap */\
lwi r15, r1, PT_R15; /* restore LP */ \
lwi r16, r1, PT_R16; \
lwi r17, r1, PT_R17; \
lwi r18, r1, PT_R18; /* restore asm scratch reg */ \
lwi r19, r1, PT_R19; \
lwi r20, r1, PT_R20; \
lwi r21, r1, PT_R21; \
lwi r22, r1, PT_R22; \
lwi r23, r1, PT_R23; \
lwi r24, r1, PT_R24; \
lwi r25, r1, PT_R25; \
lwi r26, r1, PT_R26; \
lwi r27, r1, PT_R27; \
lwi r28, r1, PT_R28; \
lwi r29, r1, PT_R29; \
lwi r30, r1, PT_R30; \
lwi r31, r1, PT_R31; /* Restore cur task reg */
#define SAVE_STATE \
swi r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* save stack */ \
/* See if already in kernel mode.*/ \
mfs r1, rmsr; \
andi r1, r1, MSR_UMS; \
bnei r1, 1f; \
/* Kernel-mode state save. */ \
/* Reload kernel stack-ptr. */ \
lwi r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); \
/* FIXME: I can add these two lines to one */ \
/* tophys(r1,r1); */ \
/* addik r1, r1, -PT_SIZE; */ \
addik r1, r1, CONFIG_KERNEL_BASE_ADDR - CONFIG_KERNEL_START - PT_SIZE; \
SAVE_REGS \
brid 2f; \
swi r1, r1, PT_MODE; \
1: /* User-mode state save. */ \
lwi r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */\
tophys(r1,r1); \
lwi r1, r1, TS_THREAD_INFO; /* get the thread info */ \
/* MS these three instructions can be added to one */ \
/* addik r1, r1, THREAD_SIZE; */ \
/* tophys(r1,r1); */ \
/* addik r1, r1, -PT_SIZE; */ \
addik r1, r1, THREAD_SIZE + CONFIG_KERNEL_BASE_ADDR - CONFIG_KERNEL_START - PT_SIZE; \
SAVE_REGS \
lwi r11, r0, TOPHYS(PER_CPU(ENTRY_SP)); \
swi r11, r1, PT_R1; /* Store user SP. */ \
swi r0, r1, PT_MODE; /* Was in user-mode. */ \
/* MS: I am clearing UMS even in case when I come from kernel space */ \
clear_ums; \
2: lwi CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
.text
/*
* User trap.
*
* System calls are handled here.
*
* Syscall protocol:
* Syscall number in r12, args in r5-r10
* Return value in r3
*
* Trap entered via brki instruction, so BIP bit is set, and interrupts
* are masked. This is nice, means we don't have to CLI before state save
*/
C_ENTRY(_user_exception):
swi r1, r0, TOPHYS(PER_CPU(ENTRY_SP)) /* save stack */
addi r14, r14, 4 /* return address is 4 byte after call */
lwi r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
tophys(r1,r1);
lwi r1, r1, TS_THREAD_INFO; /* get stack from task_struct */
/* calculate kernel stack pointer from task struct 8k */
addik r1, r1, THREAD_SIZE;
tophys(r1,r1);
addik r1, r1, -PT_SIZE; /* Make room on the stack. */
SAVE_REGS
swi r0, r1, PT_R3
swi r0, r1, PT_R4
swi r0, r1, PT_MODE; /* Was in user-mode. */
lwi r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
swi r11, r1, PT_R1; /* Store user SP. */
clear_ums;
2: lwi CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
/* Save away the syscall number. */
swi r12, r1, PT_R0;
tovirt(r1,r1)
/* where the trap should return need -8 to adjust for rtsd r15, 8*/
/* Jump to the appropriate function for the system call number in r12
* (r12 is not preserved), or return an error if r12 is not valid. The LP
* register should point to the location where
* the called function should return. [note that MAKE_SYS_CALL uses label 1] */
/* Step into virtual mode */
rtbd r0, 3f
nop
3:
lwi r11, CURRENT_TASK, TS_THREAD_INFO /* get thread info */
lwi r11, r11, TI_FLAGS /* get flags in thread info */
andi r11, r11, _TIF_WORK_SYSCALL_MASK
beqi r11, 4f
addik r3, r0, -ENOSYS
swi r3, r1, PT_R3
brlid r15, do_syscall_trace_enter
addik r5, r1, PT_R0
# do_syscall_trace_enter returns the new syscall nr.
addk r12, r0, r3
lwi r5, r1, PT_R5;
lwi r6, r1, PT_R6;
lwi r7, r1, PT_R7;
lwi r8, r1, PT_R8;
lwi r9, r1, PT_R9;
lwi r10, r1, PT_R10;
4:
/* Jump to the appropriate function for the system call number in r12
* (r12 is not preserved), or return an error if r12 is not valid.
* The LP register should point to the location where the called function
* should return. [note that MAKE_SYS_CALL uses label 1] */
/* See if the system call number is valid */
blti r12, 5f
addi r11, r12, -__NR_syscalls;
bgei r11, 5f;
/* Figure out which function to use for this system call. */
/* Note Microblaze barrel shift is optional, so don't rely on it */
add r12, r12, r12; /* convert num -> ptr */
add r12, r12, r12;
addi r30, r0, 1 /* restarts allowed */
#ifdef DEBUG
/* Trac syscalls and stored them to syscall_debug_table */
/* The first syscall location stores total syscall number */
lwi r3, r0, syscall_debug_table
addi r3, r3, 1
swi r3, r0, syscall_debug_table
lwi r3, r12, syscall_debug_table
addi r3, r3, 1
swi r3, r12, syscall_debug_table
#endif
# Find and jump into the syscall handler.
lwi r12, r12, sys_call_table
/* where the trap should return need -8 to adjust for rtsd r15, 8 */
addi r15, r0, ret_from_trap-8
bra r12
/* The syscall number is invalid, return an error. */
5:
braid ret_from_trap
addi r3, r0, -ENOSYS;
/* Entry point used to return from a syscall/trap */
/* We re-enable BIP bit before state restore */
C_ENTRY(ret_from_trap):
swi r3, r1, PT_R3
swi r4, r1, PT_R4
lwi r11, r1, PT_MODE;
/* See if returning to kernel mode, if so, skip resched &c. */
bnei r11, 2f;
/* We're returning to user mode, so check for various conditions that
* trigger rescheduling. */
/* FIXME: Restructure all these flag checks. */
lwi r11, CURRENT_TASK, TS_THREAD_INFO; /* get thread info */
lwi r11, r11, TI_FLAGS; /* get flags in thread info */
andi r11, r11, _TIF_WORK_SYSCALL_MASK
beqi r11, 1f
brlid r15, do_syscall_trace_leave
addik r5, r1, PT_R0
1:
/* We're returning to user mode, so check for various conditions that
* trigger rescheduling. */
/* get thread info from current task */
lwi r11, CURRENT_TASK, TS_THREAD_INFO;
lwi r19, r11, TI_FLAGS; /* get flags in thread info */
andi r11, r19, _TIF_NEED_RESCHED;
beqi r11, 5f;
bralid r15, schedule; /* Call scheduler */
nop; /* delay slot */
bri 1b
/* Maybe handle a signal */
5:
andi r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
beqi r11, 4f; /* Signals to handle, handle them */
addik r5, r1, 0; /* Arg 1: struct pt_regs *regs */
bralid r15, do_notify_resume; /* Handle any signals */
add r6, r30, r0; /* Arg 2: int in_syscall */
add r30, r0, r0 /* no more restarts */
bri 1b
/* Finally, return to user state. */
4: set_bip; /* Ints masked for state restore */
swi CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
VM_OFF;
tophys(r1,r1);
RESTORE_REGS;
addik r1, r1, PT_SIZE /* Clean up stack space. */
lwi r1, r1, PT_R1 - PT_SIZE;/* Restore user stack pointer. */
bri 6f;
/* Return to kernel state. */
2: set_bip; /* Ints masked for state restore */
VM_OFF;
tophys(r1,r1);
RESTORE_REGS;
addik r1, r1, PT_SIZE /* Clean up stack space. */
tovirt(r1,r1);
6:
TRAP_return: /* Make global symbol for debugging */
rtbd r14, 0; /* Instructions to return from an IRQ */
nop;
/* This the initial entry point for a new child thread, with an appropriate
stack in place that makes it look the the child is in the middle of an
syscall. This function is actually `returned to' from switch_thread
(copy_thread makes ret_from_fork the return address in each new thread's
saved context). */
C_ENTRY(ret_from_fork):
bralid r15, schedule_tail; /* ...which is schedule_tail's arg */
add r5, r3, r0; /* switch_thread returns the prev task */
/* ( in the delay slot ) */
brid ret_from_trap; /* Do normal trap return */
add r3, r0, r0; /* Child's fork call should return 0. */
C_ENTRY(ret_from_kernel_thread):
bralid r15, schedule_tail; /* ...which is schedule_tail's arg */
add r5, r3, r0; /* switch_thread returns the prev task */
/* ( in the delay slot ) */
brald r15, r20 /* fn was left in r20 */
addk r5, r0, r19 /* ... and argument - in r19 */
brid ret_from_trap
add r3, r0, r0
C_ENTRY(sys_rt_sigreturn_wrapper):
addik r30, r0, 0 /* no restarts */
brid sys_rt_sigreturn /* Do real work */
addik r5, r1, 0; /* add user context as 1st arg */
/*
* HW EXCEPTION rutine start
*/
C_ENTRY(full_exception_trap):
/* adjust exception address for privileged instruction
* for finding where is it */
addik r17, r17, -4
SAVE_STATE /* Save registers */
/* PC, before IRQ/trap - this is one instruction above */
swi r17, r1, PT_PC;
tovirt(r1,r1)
/* FIXME this can be store directly in PT_ESR reg.
* I tested it but there is a fault */
/* where the trap should return need -8 to adjust for rtsd r15, 8 */
addik r15, r0, ret_from_exc - 8
mfs r6, resr
mfs r7, rfsr; /* save FSR */
mts rfsr, r0; /* Clear sticky fsr */
rted r0, full_exception
addik r5, r1, 0 /* parameter struct pt_regs * regs */
/*
* Unaligned data trap.
*
* Unaligned data trap last on 4k page is handled here.
*
* Trap entered via exception, so EE bit is set, and interrupts
* are masked. This is nice, means we don't have to CLI before state save
*
* The assembler routine is in "arch/microblaze/kernel/hw_exception_handler.S"
*/
C_ENTRY(unaligned_data_trap):
/* MS: I have to save r11 value and then restore it because
* set_bit, clear_eip, set_ee use r11 as temp register if MSR
* instructions are not used. We don't need to do if MSR instructions
* are used and they use r0 instead of r11.
* I am using ENTRY_SP which should be primary used only for stack
* pointer saving. */
swi r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
set_bip; /* equalize initial state for all possible entries */
clear_eip;
set_ee;
lwi r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
SAVE_STATE /* Save registers.*/
/* PC, before IRQ/trap - this is one instruction above */
swi r17, r1, PT_PC;
tovirt(r1,r1)
/* where the trap should return need -8 to adjust for rtsd r15, 8 */
addik r15, r0, ret_from_exc-8
mfs r3, resr /* ESR */
mfs r4, rear /* EAR */
rtbd r0, _unaligned_data_exception
addik r7, r1, 0 /* parameter struct pt_regs * regs */
/*
* Page fault traps.
*
* If the real exception handler (from hw_exception_handler.S) didn't find
* the mapping for the process, then we're thrown here to handle such situation.
*
* Trap entered via exceptions, so EE bit is set, and interrupts
* are masked. This is nice, means we don't have to CLI before state save
*
* Build a standard exception frame for TLB Access errors. All TLB exceptions
* will bail out to this point if they can't resolve the lightweight TLB fault.
*
* The C function called is in "arch/microblaze/mm/fault.c", declared as:
* void do_page_fault(struct pt_regs *regs,
* unsigned long address,
* unsigned long error_code)
*/
/* data and intruction trap - which is choose is resolved int fault.c */
C_ENTRY(page_fault_data_trap):
SAVE_STATE /* Save registers.*/
/* PC, before IRQ/trap - this is one instruction above */
swi r17, r1, PT_PC;
tovirt(r1,r1)
/* where the trap should return need -8 to adjust for rtsd r15, 8 */
addik r15, r0, ret_from_exc-8
mfs r6, rear /* parameter unsigned long address */
mfs r7, resr /* parameter unsigned long error_code */
rted r0, do_page_fault
addik r5, r1, 0 /* parameter struct pt_regs * regs */
C_ENTRY(page_fault_instr_trap):
SAVE_STATE /* Save registers.*/
/* PC, before IRQ/trap - this is one instruction above */
swi r17, r1, PT_PC;
tovirt(r1,r1)
/* where the trap should return need -8 to adjust for rtsd r15, 8 */
addik r15, r0, ret_from_exc-8
mfs r6, rear /* parameter unsigned long address */
ori r7, r0, 0 /* parameter unsigned long error_code */
rted r0, do_page_fault
addik r5, r1, 0 /* parameter struct pt_regs * regs */
/* Entry point used to return from an exception. */
C_ENTRY(ret_from_exc):
lwi r11, r1, PT_MODE;
bnei r11, 2f; /* See if returning to kernel mode, */
/* ... if so, skip resched &c. */
/* We're returning to user mode, so check for various conditions that
trigger rescheduling. */
1:
lwi r11, CURRENT_TASK, TS_THREAD_INFO; /* get thread info */
lwi r19, r11, TI_FLAGS; /* get flags in thread info */
andi r11, r19, _TIF_NEED_RESCHED;
beqi r11, 5f;
/* Call the scheduler before returning from a syscall/trap. */
bralid r15, schedule; /* Call scheduler */
nop; /* delay slot */
bri 1b
/* Maybe handle a signal */
5: andi r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
beqi r11, 4f; /* Signals to handle, handle them */
/*
* Handle a signal return; Pending signals should be in r18.
*
* Not all registers are saved by the normal trap/interrupt entry
* points (for instance, call-saved registers (because the normal
* C-compiler calling sequence in the kernel makes sure they're
* preserved), and call-clobbered registers in the case of
* traps), but signal handlers may want to examine or change the
* complete register state. Here we save anything not saved by
* the normal entry sequence, so that it may be safely restored
* (in a possibly modified form) after do_notify_resume returns. */
addik r5, r1, 0; /* Arg 1: struct pt_regs *regs */
bralid r15, do_notify_resume; /* Handle any signals */
addi r6, r0, 0; /* Arg 2: int in_syscall */
bri 1b
/* Finally, return to user state. */
4: set_bip; /* Ints masked for state restore */
swi CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
VM_OFF;
tophys(r1,r1);
RESTORE_REGS;
addik r1, r1, PT_SIZE /* Clean up stack space. */
lwi r1, r1, PT_R1 - PT_SIZE; /* Restore user stack pointer. */
bri 6f;
/* Return to kernel state. */
2: set_bip; /* Ints masked for state restore */
VM_OFF;
tophys(r1,r1);
RESTORE_REGS;
addik r1, r1, PT_SIZE /* Clean up stack space. */
tovirt(r1,r1);
6:
EXC_return: /* Make global symbol for debugging */
rtbd r14, 0; /* Instructions to return from an IRQ */
nop;
/*
* HW EXCEPTION rutine end
*/
/*
* Hardware maskable interrupts.
*
* The stack-pointer (r1) should have already been saved to the memory
* location PER_CPU(ENTRY_SP).
*/
C_ENTRY(_interrupt):
/* MS: we are in physical address */
/* Save registers, switch to proper stack, convert SP to virtual.*/
swi r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
/* MS: See if already in kernel mode. */
mfs r1, rmsr
nop
andi r1, r1, MSR_UMS
bnei r1, 1f
/* Kernel-mode state save. */
lwi r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
tophys(r1,r1); /* MS: I have in r1 physical address where stack is */
/* save registers */
/* MS: Make room on the stack -> activation record */
addik r1, r1, -PT_SIZE;
SAVE_REGS
brid 2f;
swi r1, r1, PT_MODE; /* 0 - user mode, 1 - kernel mode */
1:
/* User-mode state save. */
/* MS: get the saved current */
lwi r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
tophys(r1,r1);
lwi r1, r1, TS_THREAD_INFO;
addik r1, r1, THREAD_SIZE;
tophys(r1,r1);
/* save registers */
addik r1, r1, -PT_SIZE;
SAVE_REGS
/* calculate mode */
swi r0, r1, PT_MODE;
lwi r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
swi r11, r1, PT_R1;
clear_ums;
2:
lwi CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
tovirt(r1,r1)
addik r15, r0, irq_call;
irq_call:rtbd r0, do_IRQ;
addik r5, r1, 0;
/* MS: we are in virtual mode */
ret_from_irq:
lwi r11, r1, PT_MODE;
bnei r11, 2f;
1:
lwi r11, CURRENT_TASK, TS_THREAD_INFO;
lwi r19, r11, TI_FLAGS; /* MS: get flags from thread info */
andi r11, r19, _TIF_NEED_RESCHED;
beqi r11, 5f
bralid r15, schedule;
nop; /* delay slot */
bri 1b
/* Maybe handle a signal */
5: andi r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
beqid r11, no_intr_resched
/* Handle a signal return; Pending signals should be in r18. */
addik r5, r1, 0; /* Arg 1: struct pt_regs *regs */
bralid r15, do_notify_resume; /* Handle any signals */
addi r6, r0, 0; /* Arg 2: int in_syscall */
bri 1b
/* Finally, return to user state. */
no_intr_resched:
/* Disable interrupts, we are now committed to the state restore */
disable_irq
swi CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE);
VM_OFF;
tophys(r1,r1);
RESTORE_REGS
addik r1, r1, PT_SIZE /* MS: Clean up stack space. */
lwi r1, r1, PT_R1 - PT_SIZE;
bri 6f;
/* MS: Return to kernel state. */
2:
#ifdef CONFIG_PREEMPT
lwi r11, CURRENT_TASK, TS_THREAD_INFO;
/* MS: get preempt_count from thread info */
lwi r5, r11, TI_PREEMPT_COUNT;
bgti r5, restore;
lwi r5, r11, TI_FLAGS; /* get flags in thread info */
andi r5, r5, _TIF_NEED_RESCHED;
beqi r5, restore /* if zero jump over */
preempt:
/* interrupts are off that's why I am calling preempt_chedule_irq */
bralid r15, preempt_schedule_irq
nop
lwi r11, CURRENT_TASK, TS_THREAD_INFO; /* get thread info */
lwi r5, r11, TI_FLAGS; /* get flags in thread info */
andi r5, r5, _TIF_NEED_RESCHED;
bnei r5, preempt /* if non zero jump to resched */
restore:
#endif
VM_OFF /* MS: turn off MMU */
tophys(r1,r1)
RESTORE_REGS
addik r1, r1, PT_SIZE /* MS: Clean up stack space. */
tovirt(r1,r1);
6:
IRQ_return: /* MS: Make global symbol for debugging */
rtid r14, 0
nop
/*
* Debug trap for KGDB. Enter to _debug_exception by brki r16, 0x18
* and call handling function with saved pt_regs
*/
C_ENTRY(_debug_exception):
/* BIP bit is set on entry, no interrupts can occur */
swi r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
mfs r1, rmsr
nop
andi r1, r1, MSR_UMS
bnei r1, 1f
/* MS: Kernel-mode state save - kgdb */
lwi r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
/* BIP bit is set on entry, no interrupts can occur */
addik r1, r1, CONFIG_KERNEL_BASE_ADDR - CONFIG_KERNEL_START - PT_SIZE;
SAVE_REGS;
/* save all regs to pt_reg structure */
swi r0, r1, PT_R0; /* R0 must be saved too */
swi r14, r1, PT_R14 /* rewrite saved R14 value */
swi r16, r1, PT_PC; /* PC and r16 are the same */
/* save special purpose registers to pt_regs */
mfs r11, rear;
swi r11, r1, PT_EAR;
mfs r11, resr;
swi r11, r1, PT_ESR;
mfs r11, rfsr;
swi r11, r1, PT_FSR;
/* stack pointer is in physical address at it is decrease
* by PT_SIZE but we need to get correct R1 value */
addik r11, r1, CONFIG_KERNEL_START - CONFIG_KERNEL_BASE_ADDR + PT_SIZE;
swi r11, r1, PT_R1
/* MS: r31 - current pointer isn't changed */
tovirt(r1,r1)
#ifdef CONFIG_KGDB
addi r5, r1, 0 /* pass pt_reg address as the first arg */
addik r15, r0, dbtrap_call; /* return address */
rtbd r0, microblaze_kgdb_break
nop;
#endif
/* MS: Place handler for brki from kernel space if KGDB is OFF.
* It is very unlikely that another brki instruction is called. */
bri 0
/* MS: User-mode state save - gdb */
1: lwi r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
tophys(r1,r1);
lwi r1, r1, TS_THREAD_INFO; /* get the thread info */
addik r1, r1, THREAD_SIZE; /* calculate kernel stack pointer */
tophys(r1,r1);
addik r1, r1, -PT_SIZE; /* Make room on the stack. */
SAVE_REGS;
swi r16, r1, PT_PC; /* Save LP */
swi r0, r1, PT_MODE; /* Was in user-mode. */
lwi r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
swi r11, r1, PT_R1; /* Store user SP. */
lwi CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
tovirt(r1,r1)
set_vms;
addik r5, r1, 0;
addik r15, r0, dbtrap_call;
dbtrap_call: /* Return point for kernel/user entry + 8 because of rtsd r15, 8 */
rtbd r0, sw_exception
nop
/* MS: The first instruction for the second part of the gdb/kgdb */
set_bip; /* Ints masked for state restore */
lwi r11, r1, PT_MODE;
bnei r11, 2f;
/* MS: Return to user space - gdb */
1:
/* Get current task ptr into r11 */
lwi r11, CURRENT_TASK, TS_THREAD_INFO; /* get thread info */
lwi r19, r11, TI_FLAGS; /* get flags in thread info */
andi r11, r19, _TIF_NEED_RESCHED;
beqi r11, 5f;
/* Call the scheduler before returning from a syscall/trap. */
bralid r15, schedule; /* Call scheduler */
nop; /* delay slot */
bri 1b
/* Maybe handle a signal */
5: andi r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
beqi r11, 4f; /* Signals to handle, handle them */
addik r5, r1, 0; /* Arg 1: struct pt_regs *regs */
bralid r15, do_notify_resume; /* Handle any signals */
addi r6, r0, 0; /* Arg 2: int in_syscall */
bri 1b
/* Finally, return to user state. */
4: swi CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
VM_OFF;
tophys(r1,r1);
/* MS: Restore all regs */
RESTORE_REGS
addik r1, r1, PT_SIZE /* Clean up stack space */
lwi r1, r1, PT_R1 - PT_SIZE; /* Restore user stack pointer */
DBTRAP_return_user: /* MS: Make global symbol for debugging */
rtbd r16, 0; /* MS: Instructions to return from a debug trap */
nop;
/* MS: Return to kernel state - kgdb */
2: VM_OFF;
tophys(r1,r1);
/* MS: Restore all regs */
RESTORE_REGS
lwi r14, r1, PT_R14;
lwi r16, r1, PT_PC;
addik r1, r1, PT_SIZE; /* MS: Clean up stack space */
tovirt(r1,r1);
DBTRAP_return_kernel: /* MS: Make global symbol for debugging */
rtbd r16, 0; /* MS: Instructions to return from a debug trap */
nop;
ENTRY(_switch_to)
/* prepare return value */
addk r3, r0, CURRENT_TASK
/* save registers in cpu_context */
/* use r11 and r12, volatile registers, as temp register */
/* give start of cpu_context for previous process */
addik r11, r5, TI_CPU_CONTEXT
swi r1, r11, CC_R1
swi r2, r11, CC_R2
/* skip volatile registers.
* they are saved on stack when we jumped to _switch_to() */
/* dedicated registers */
swi r13, r11, CC_R13
swi r14, r11, CC_R14
swi r15, r11, CC_R15
swi r16, r11, CC_R16
swi r17, r11, CC_R17
swi r18, r11, CC_R18
/* save non-volatile registers */
swi r19, r11, CC_R19
swi r20, r11, CC_R20
swi r21, r11, CC_R21
swi r22, r11, CC_R22
swi r23, r11, CC_R23
swi r24, r11, CC_R24
swi r25, r11, CC_R25
swi r26, r11, CC_R26
swi r27, r11, CC_R27
swi r28, r11, CC_R28
swi r29, r11, CC_R29
swi r30, r11, CC_R30
/* special purpose registers */
mfs r12, rmsr
swi r12, r11, CC_MSR
mfs r12, rear
swi r12, r11, CC_EAR
mfs r12, resr
swi r12, r11, CC_ESR
mfs r12, rfsr
swi r12, r11, CC_FSR
/* update r31, the current-give me pointer to task which will be next */
lwi CURRENT_TASK, r6, TI_TASK
/* stored it to current_save too */
swi CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE)
/* get new process' cpu context and restore */
/* give me start where start context of next task */
addik r11, r6, TI_CPU_CONTEXT
/* non-volatile registers */
lwi r30, r11, CC_R30
lwi r29, r11, CC_R29
lwi r28, r11, CC_R28
lwi r27, r11, CC_R27
lwi r26, r11, CC_R26
lwi r25, r11, CC_R25
lwi r24, r11, CC_R24
lwi r23, r11, CC_R23
lwi r22, r11, CC_R22
lwi r21, r11, CC_R21
lwi r20, r11, CC_R20
lwi r19, r11, CC_R19
/* dedicated registers */
lwi r18, r11, CC_R18
lwi r17, r11, CC_R17
lwi r16, r11, CC_R16
lwi r15, r11, CC_R15
lwi r14, r11, CC_R14
lwi r13, r11, CC_R13
/* skip volatile registers */
lwi r2, r11, CC_R2
lwi r1, r11, CC_R1
/* special purpose registers */
lwi r12, r11, CC_FSR
mts rfsr, r12
lwi r12, r11, CC_MSR
mts rmsr, r12
rtsd r15, 8
nop
ENTRY(_reset)
brai 0; /* Jump to reset vector */
/* These are compiled and loaded into high memory, then
* copied into place in mach_early_setup */
.section .init.ivt, "ax"
#if CONFIG_MANUAL_RESET_VECTOR
.org 0x0
brai CONFIG_MANUAL_RESET_VECTOR
#endif
.org 0x8
brai TOPHYS(_user_exception); /* syscall handler */
.org 0x10
brai TOPHYS(_interrupt); /* Interrupt handler */
.org 0x18
brai TOPHYS(_debug_exception); /* debug trap handler */
.org 0x20
brai TOPHYS(_hw_exception_handler); /* HW exception handler */
.section .rodata,"a"
#include "syscall_table.S"
syscall_table_size=(.-sys_call_table)
type_SYSCALL:
.ascii "SYSCALL\0"
type_IRQ:
.ascii "IRQ\0"
type_IRQ_PREEMPT:
.ascii "IRQ (PREEMPTED)\0"
type_SYSCALL_PREEMPT:
.ascii " SYSCALL (PREEMPTED)\0"
/*
* Trap decoding for stack unwinder
* Tuples are (start addr, end addr, string)
* If return address lies on [start addr, end addr],
* unwinder displays 'string'
*/
.align 4
.global microblaze_trap_handlers
microblaze_trap_handlers:
/* Exact matches come first */
.word ret_from_trap; .word ret_from_trap ; .word type_SYSCALL
.word ret_from_irq ; .word ret_from_irq ; .word type_IRQ
/* Fuzzy matches go here */
.word ret_from_irq ; .word no_intr_resched ; .word type_IRQ_PREEMPT
.word ret_from_trap; .word TRAP_return ; .word type_SYSCALL_PREEMPT
/* End of table */
.word 0 ; .word 0 ; .word 0
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