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kernel_optimize_test/arch/xtensa/kernel/traps.c
Max Filippov 3cfc096e4c xtensa: don't allow overflow/underflow on unaligned stack 
Double exceptions that happen during register window overflow/underflow
are handled in the topmost stack frame, as if it was the only exception
that occured. However unaligned access exception handler is special
because it needs to analyze instruction that caused the exception, but
the userspace instruction that triggered window exception is completely
irrelevant. Unaligned data access is rather normal in the generic
userspace code, but stack pointer manipulation must always be done by
architecture-aware code and thus unaligned stack means a serious problem
anyway.
Use the default unaligned access handler that raises SIGBUS in case
of unaligned access in window overflow/underflow handler.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2014-08-14 11:59:32 +04:00

518 lines
12 KiB
C
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/*
* arch/xtensa/kernel/traps.c
*
* Exception handling.
*
* Derived from code with the following copyrights:
* Copyright (C) 1994 - 1999 by Ralf Baechle
* Modified for R3000 by Paul M. Antoine, 1995, 1996
* Complete output from die() by Ulf Carlsson, 1998
* Copyright (C) 1999 Silicon Graphics, Inc.
*
* Essentially rewritten for the Xtensa architecture port.
*
* Copyright (C) 2001 - 2013 Tensilica Inc.
*
* Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
* Chris Zankel <chris@zankel.net>
* Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca>
* Kevin Chea
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/kallsyms.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <asm/stacktrace.h>
#include <asm/ptrace.h>
#include <asm/timex.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/traps.h>
#ifdef CONFIG_KGDB
extern int gdb_enter;
extern int return_from_debug_flag;
#endif
/*
* Machine specific interrupt handlers
*/
extern void kernel_exception(void);
extern void user_exception(void);
extern void fast_syscall_kernel(void);
extern void fast_syscall_user(void);
extern void fast_alloca(void);
extern void fast_unaligned(void);
extern void fast_second_level_miss(void);
extern void fast_store_prohibited(void);
extern void fast_coprocessor(void);
extern void do_illegal_instruction (struct pt_regs*);
extern void do_interrupt (struct pt_regs*);
extern void do_unaligned_user (struct pt_regs*);
extern void do_multihit (struct pt_regs*, unsigned long);
extern void do_page_fault (struct pt_regs*, unsigned long);
extern void do_debug (struct pt_regs*);
extern void system_call (struct pt_regs*);
/*
* The vector table must be preceded by a save area (which
* implies it must be in RAM, unless one places RAM immediately
* before a ROM and puts the vector at the start of the ROM (!))
*/
#define KRNL 0x01
#define USER 0x02
#define COPROCESSOR(x) \
{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
typedef struct {
int cause;
int fast;
void* handler;
} dispatch_init_table_t;
static dispatch_init_table_t __initdata dispatch_init_table[] = {
{ EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
{ EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel },
{ EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
{ EXCCAUSE_SYSTEM_CALL, 0, system_call },
/* EXCCAUSE_INSTRUCTION_FETCH unhandled */
/* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
{ EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
{ EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
/* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
/* EXCCAUSE_PRIVILEGED unhandled */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
#ifdef CONFIG_XTENSA_UNALIGNED_USER
{ EXCCAUSE_UNALIGNED, USER, fast_unaligned },
#endif
{ EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
{ EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
#endif
#ifdef CONFIG_MMU
{ EXCCAUSE_ITLB_MISS, 0, do_page_fault },
{ EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
{ EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
/* EXCCAUSE_SIZE_RESTRICTION unhandled */
{ EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
{ EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_DTLB_MISS, 0, do_page_fault },
{ EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
{ EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
/* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
{ EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
#endif /* CONFIG_MMU */
/* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
#if XTENSA_HAVE_COPROCESSOR(0)
COPROCESSOR(0),
#endif
#if XTENSA_HAVE_COPROCESSOR(1)
COPROCESSOR(1),
#endif
#if XTENSA_HAVE_COPROCESSOR(2)
COPROCESSOR(2),
#endif
#if XTENSA_HAVE_COPROCESSOR(3)
COPROCESSOR(3),
#endif
#if XTENSA_HAVE_COPROCESSOR(4)
COPROCESSOR(4),
#endif
#if XTENSA_HAVE_COPROCESSOR(5)
COPROCESSOR(5),
#endif
#if XTENSA_HAVE_COPROCESSOR(6)
COPROCESSOR(6),
#endif
#if XTENSA_HAVE_COPROCESSOR(7)
COPROCESSOR(7),
#endif
{ EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
{ -1, -1, 0 }
};
/* The exception table <exc_table> serves two functions:
* 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
* 2. it is a temporary memory buffer for the exception handlers.
*/
DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
void die(const char*, struct pt_regs*, long);
static inline void
__die_if_kernel(const char *str, struct pt_regs *regs, long err)
{
if (!user_mode(regs))
die(str, regs, err);
}
/*
* Unhandled Exceptions. Kill user task or panic if in kernel space.
*/
void do_unhandled(struct pt_regs *regs, unsigned long exccause)
{
__die_if_kernel("Caught unhandled exception - should not happen",
regs, SIGKILL);
/* If in user mode, send SIGILL signal to current process */
printk("Caught unhandled exception in '%s' "
"(pid = %d, pc = %#010lx) - should not happen\n"
"\tEXCCAUSE is %ld\n",
current->comm, task_pid_nr(current), regs->pc, exccause);
force_sig(SIGILL, current);
}
/*
* Multi-hit exception. This if fatal!
*/
void do_multihit(struct pt_regs *regs, unsigned long exccause)
{
die("Caught multihit exception", regs, SIGKILL);
}
/*
* IRQ handler.
*/
extern void do_IRQ(int, struct pt_regs *);
void do_interrupt(struct pt_regs *regs)
{
static const unsigned int_level_mask[] = {
0,
XCHAL_INTLEVEL1_MASK,
XCHAL_INTLEVEL2_MASK,
XCHAL_INTLEVEL3_MASK,
XCHAL_INTLEVEL4_MASK,
XCHAL_INTLEVEL5_MASK,
XCHAL_INTLEVEL6_MASK,
XCHAL_INTLEVEL7_MASK,
};
struct pt_regs *old_regs = set_irq_regs(regs);
irq_enter();
for (;;) {
unsigned intread = get_sr(interrupt);
unsigned intenable = get_sr(intenable);
unsigned int_at_level = intread & intenable;
unsigned level;
for (level = LOCKLEVEL; level > 0; --level) {
if (int_at_level & int_level_mask[level]) {
int_at_level &= int_level_mask[level];
break;
}
}
if (level == 0)
break;
do_IRQ(__ffs(int_at_level), regs);
}
irq_exit();
set_irq_regs(old_regs);
}
/*
* Illegal instruction. Fatal if in kernel space.
*/
void
do_illegal_instruction(struct pt_regs *regs)
{
__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
/* If in user mode, send SIGILL signal to current process. */
printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
current->comm, task_pid_nr(current), regs->pc);
force_sig(SIGILL, current);
}
/*
* Handle unaligned memory accesses from user space. Kill task.
*
* If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
* accesses causes from user space.
*/
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
void
do_unaligned_user (struct pt_regs *regs)
{
siginfo_t info;
__die_if_kernel("Unhandled unaligned exception in kernel",
regs, SIGKILL);
current->thread.bad_vaddr = regs->excvaddr;
current->thread.error_code = -3;
printk("Unaligned memory access to %08lx in '%s' "
"(pid = %d, pc = %#010lx)\n",
regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRALN;
info.si_addr = (void *) regs->excvaddr;
force_sig_info(SIGSEGV, &info, current);
}
#endif
void
do_debug(struct pt_regs *regs)
{
#ifdef CONFIG_KGDB
/* If remote debugging is configured AND enabled, we give control to
* kgdb. Otherwise, we fall through, perhaps giving control to the
* native debugger.
*/
if (gdb_enter) {
extern void gdb_handle_exception(struct pt_regs *);
gdb_handle_exception(regs);
return_from_debug_flag = 1;
return;
}
#endif
__die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
/* If in user mode, send SIGTRAP signal to current process */
force_sig(SIGTRAP, current);
}
static void set_handler(int idx, void *handler)
{
unsigned int cpu;
for_each_possible_cpu(cpu)
per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
}
/* Set exception C handler - for temporary use when probing exceptions */
void * __init trap_set_handler(int cause, void *handler)
{
void *previous = (void *)per_cpu(exc_table, 0)[
EXC_TABLE_DEFAULT / 4 + cause];
set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
return previous;
}
static void trap_init_excsave(void)
{
unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
__asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1));
}
/*
* Initialize dispatch tables.
*
* The exception vectors are stored compressed the __init section in the
* dispatch_init_table. This function initializes the following three tables
* from that compressed table:
* - fast user first dispatch table for user exceptions
* - fast kernel first dispatch table for kernel exceptions
* - default C-handler C-handler called by the default fast handler.
*
* See vectors.S for more details.
*/
void __init trap_init(void)
{
int i;
/* Setup default vectors. */
for(i = 0; i < 64; i++) {
set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception);
set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
}
/* Setup specific handlers. */
for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
int fast = dispatch_init_table[i].fast;
int cause = dispatch_init_table[i].cause;
void *handler = dispatch_init_table[i].handler;
if (fast == 0)
set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
if (fast && fast & USER)
set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
if (fast && fast & KRNL)
set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
}
/* Initialize EXCSAVE_1 to hold the address of the exception table. */
trap_init_excsave();
}
#ifdef CONFIG_SMP
void secondary_trap_init(void)
{
trap_init_excsave();
}
#endif
/*
* This function dumps the current valid window frame and other base registers.
*/
void show_regs(struct pt_regs * regs)
{
int i, wmask;
show_regs_print_info(KERN_DEFAULT);
wmask = regs->wmask & ~1;
for (i = 0; i < 16; i++) {
if ((i % 8) == 0)
printk(KERN_INFO "a%02d:", i);
printk(KERN_CONT " %08lx", regs->areg[i]);
}
printk(KERN_CONT "\n");
printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
regs->pc, regs->ps, regs->depc, regs->excvaddr);
printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
regs->lbeg, regs->lend, regs->lcount, regs->sar);
if (user_mode(regs))
printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
regs->windowbase, regs->windowstart, regs->wmask,
regs->syscall);
}
static int show_trace_cb(struct stackframe *frame, void *data)
{
if (kernel_text_address(frame->pc)) {
printk(" [<%08lx>] ", frame->pc);
print_symbol("%s\n", frame->pc);
}
return 0;
}
void show_trace(struct task_struct *task, unsigned long *sp)
{
if (!sp)
sp = stack_pointer(task);
printk("Call Trace:");
#ifdef CONFIG_KALLSYMS
printk("\n");
#endif
walk_stackframe(sp, show_trace_cb, NULL);
printk("\n");
}
/*
* This routine abuses get_user()/put_user() to reference pointers
* with at least a bit of error checking ...
*/
static int kstack_depth_to_print = 24;
void show_stack(struct task_struct *task, unsigned long *sp)
{
int i = 0;
unsigned long *stack;
if (!sp)
sp = stack_pointer(task);
stack = sp;
printk("\nStack: ");
for (i = 0; i < kstack_depth_to_print; i++) {
if (kstack_end(sp))
break;
if (i && ((i % 8) == 0))
printk("\n ");
printk("%08lx ", *sp++);
}
printk("\n");
show_trace(task, stack);
}
void show_code(unsigned int *pc)
{
long i;
printk("\nCode:");
for(i = -3 ; i < 6 ; i++) {
unsigned long insn;
if (__get_user(insn, pc + i)) {
printk(" (Bad address in pc)\n");
break;
}
printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
}
}
DEFINE_SPINLOCK(die_lock);
void die(const char * str, struct pt_regs * regs, long err)
{
static int die_counter;
int nl = 0;
console_verbose();
spin_lock_irq(&die_lock);
printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
#ifdef CONFIG_PREEMPT
printk("PREEMPT ");
nl = 1;
#endif
if (nl)
printk("\n");
show_regs(regs);
if (!user_mode(regs))
show_stack(NULL, (unsigned long*)regs->areg[1]);
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
spin_unlock_irq(&die_lock);
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
do_exit(err);
}
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