linux_old1/arch/arm/kernel/traps.c

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/*
* linux/arch/arm/kernel/traps.c
*
* Copyright (C) 1995-2009 Russell King
* Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 'traps.c' handles hardware exceptions after we have saved some state in
* 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably
* kill the offending process.
*/
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/system.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/unwind.h>
#include <asm/tls.h>
#include "ptrace.h"
#include "signal.h"
static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
#ifdef CONFIG_DEBUG_USER
unsigned int user_debug;
static int __init user_debug_setup(char *str)
{
get_option(&str, &user_debug);
return 1;
}
__setup("user_debug=", user_debug_setup);
#endif
static void dump_mem(const char *, const char *, unsigned long, unsigned long);
void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
{
#ifdef CONFIG_KALLSYMS
printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
#else
printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
#endif
if (in_exception_text(where))
dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
}
#ifndef CONFIG_ARM_UNWIND
/*
* Stack pointers should always be within the kernels view of
* physical memory. If it is not there, then we can't dump
* out any information relating to the stack.
*/
static int verify_stack(unsigned long sp)
{
if (sp < PAGE_OFFSET ||
(sp > (unsigned long)high_memory && high_memory != NULL))
return -EFAULT;
return 0;
}
#endif
/*
* Dump out the contents of some memory nicely...
*/
static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
unsigned long top)
{
unsigned long first;
mm_segment_t fs;
int i;
/*
* We need to switch to kernel mode so that we can use __get_user
* to safely read from kernel space. Note that we now dump the
* code first, just in case the backtrace kills us.
*/
fs = get_fs();
set_fs(KERNEL_DS);
printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
for (first = bottom & ~31; first < top; first += 32) {
unsigned long p;
char str[sizeof(" 12345678") * 8 + 1];
memset(str, ' ', sizeof(str));
str[sizeof(str) - 1] = '\0';
for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
if (p >= bottom && p < top) {
unsigned long val;
if (__get_user(val, (unsigned long *)p) == 0)
sprintf(str + i * 9, " %08lx", val);
else
sprintf(str + i * 9, " ????????");
}
}
printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
}
set_fs(fs);
}
static void dump_instr(const char *lvl, struct pt_regs *regs)
{
unsigned long addr = instruction_pointer(regs);
const int thumb = thumb_mode(regs);
const int width = thumb ? 4 : 8;
mm_segment_t fs;
char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
int i;
/*
* We need to switch to kernel mode so that we can use __get_user
* to safely read from kernel space. Note that we now dump the
* code first, just in case the backtrace kills us.
*/
fs = get_fs();
set_fs(KERNEL_DS);
for (i = -4; i < 1; i++) {
unsigned int val, bad;
if (thumb)
bad = __get_user(val, &((u16 *)addr)[i]);
else
bad = __get_user(val, &((u32 *)addr)[i]);
if (!bad)
p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
width, val);
else {
p += sprintf(p, "bad PC value");
break;
}
}
printk("%sCode: %s\n", lvl, str);
set_fs(fs);
}
#ifdef CONFIG_ARM_UNWIND
static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
unwind_backtrace(regs, tsk);
}
#else
static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
unsigned int fp, mode;
int ok = 1;
printk("Backtrace: ");
if (!tsk)
tsk = current;
if (regs) {
fp = regs->ARM_fp;
mode = processor_mode(regs);
} else if (tsk != current) {
fp = thread_saved_fp(tsk);
mode = 0x10;
} else {
asm("mov %0, fp" : "=r" (fp) : : "cc");
mode = 0x10;
}
if (!fp) {
printk("no frame pointer");
ok = 0;
} else if (verify_stack(fp)) {
printk("invalid frame pointer 0x%08x", fp);
ok = 0;
} else if (fp < (unsigned long)end_of_stack(tsk))
printk("frame pointer underflow");
printk("\n");
if (ok)
c_backtrace(fp, mode);
}
#endif
void dump_stack(void)
{
dump_backtrace(NULL, NULL);
}
EXPORT_SYMBOL(dump_stack);
void show_stack(struct task_struct *tsk, unsigned long *sp)
{
dump_backtrace(NULL, tsk);
barrier();
}
#ifdef CONFIG_PREEMPT
#define S_PREEMPT " PREEMPT"
#else
#define S_PREEMPT ""
#endif
#ifdef CONFIG_SMP
#define S_SMP " SMP"
#else
#define S_SMP ""
#endif
static int __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
{
struct task_struct *tsk = thread->task;
static int die_counter;
int ret;
printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
str, err, ++die_counter);
sysfs_printk_last_file();
/* trap and error numbers are mostly meaningless on ARM */
ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
if (ret == NOTIFY_STOP)
return ret;
print_modules();
__show_regs(regs);
printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
if (!user_mode(regs) || in_interrupt()) {
dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
THREAD_SIZE + (unsigned long)task_stack_page(tsk));
dump_backtrace(regs, tsk);
dump_instr(KERN_EMERG, regs);
}
return ret;
}
DEFINE_SPINLOCK(die_lock);
/*
* This function is protected against re-entrancy.
*/
void die(const char *str, struct pt_regs *regs, int err)
{
struct thread_info *thread = current_thread_info();
int ret;
oops_enter();
spin_lock_irq(&die_lock);
console_verbose();
bust_spinlocks(1);
ret = __die(str, err, thread, regs);
if (regs && kexec_should_crash(thread->task))
crash_kexec(regs);
bust_spinlocks(0);
add_taint(TAINT_DIE);
spin_unlock_irq(&die_lock);
oops_exit();
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
if (ret != NOTIFY_STOP)
do_exit(SIGSEGV);
}
void arm_notify_die(const char *str, struct pt_regs *regs,
struct siginfo *info, unsigned long err, unsigned long trap)
{
if (user_mode(regs)) {
current->thread.error_code = err;
current->thread.trap_no = trap;
force_sig_info(info->si_signo, info, current);
} else {
die(str, regs, err);
}
}
static LIST_HEAD(undef_hook);
static DEFINE_SPINLOCK(undef_lock);
void register_undef_hook(struct undef_hook *hook)
{
unsigned long flags;
spin_lock_irqsave(&undef_lock, flags);
list_add(&hook->node, &undef_hook);
spin_unlock_irqrestore(&undef_lock, flags);
}
void unregister_undef_hook(struct undef_hook *hook)
{
unsigned long flags;
spin_lock_irqsave(&undef_lock, flags);
list_del(&hook->node);
spin_unlock_irqrestore(&undef_lock, flags);
}
static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
{
struct undef_hook *hook;
unsigned long flags;
int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
spin_lock_irqsave(&undef_lock, flags);
list_for_each_entry(hook, &undef_hook, node)
if ((instr & hook->instr_mask) == hook->instr_val &&
(regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
fn = hook->fn;
spin_unlock_irqrestore(&undef_lock, flags);
return fn ? fn(regs, instr) : 1;
}
asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
{
unsigned int correction = thumb_mode(regs) ? 2 : 4;
unsigned int instr;
siginfo_t info;
void __user *pc;
/*
* According to the ARM ARM, PC is 2 or 4 bytes ahead,
* depending whether we're in Thumb mode or not.
* Correct this offset.
*/
regs->ARM_pc -= correction;
pc = (void __user *)instruction_pointer(regs);
if (processor_mode(regs) == SVC_MODE) {
instr = *(u32 *) pc;
} else if (thumb_mode(regs)) {
get_user(instr, (u16 __user *)pc);
} else {
get_user(instr, (u32 __user *)pc);
}
if (call_undef_hook(regs, instr) == 0)
return;
#ifdef CONFIG_DEBUG_USER
if (user_debug & UDBG_UNDEFINED) {
printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
current->comm, task_pid_nr(current), pc);
dump_instr(KERN_INFO, regs);
}
#endif
info.si_signo = SIGILL;
info.si_errno = 0;
info.si_code = ILL_ILLOPC;
info.si_addr = pc;
arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
}
asmlinkage void do_unexp_fiq (struct pt_regs *regs)
{
printk("Hmm. Unexpected FIQ received, but trying to continue\n");
printk("You may have a hardware problem...\n");
}
/*
* bad_mode handles the impossible case in the vectors. If you see one of
* these, then it's extremely serious, and could mean you have buggy hardware.
* It never returns, and never tries to sync. We hope that we can at least
* dump out some state information...
*/
asmlinkage void bad_mode(struct pt_regs *regs, int reason)
{
console_verbose();
printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
die("Oops - bad mode", regs, 0);
local_irq_disable();
panic("bad mode");
}
static int bad_syscall(int n, struct pt_regs *regs)
{
struct thread_info *thread = current_thread_info();
siginfo_t info;
if (current->personality != PER_LINUX &&
current->personality != PER_LINUX_32BIT &&
thread->exec_domain->handler) {
thread->exec_domain->handler(n, regs);
return regs->ARM_r0;
}
#ifdef CONFIG_DEBUG_USER
if (user_debug & UDBG_SYSCALL) {
printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
task_pid_nr(current), current->comm, n);
dump_instr(KERN_ERR, regs);
}
#endif
info.si_signo = SIGILL;
info.si_errno = 0;
info.si_code = ILL_ILLTRP;
info.si_addr = (void __user *)instruction_pointer(regs) -
(thumb_mode(regs) ? 2 : 4);
arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
return regs->ARM_r0;
}
static inline void
do_cache_op(unsigned long start, unsigned long end, int flags)
{
struct mm_struct *mm = current->active_mm;
struct vm_area_struct *vma;
if (end < start || flags)
return;
down_read(&mm->mmap_sem);
vma = find_vma(mm, start);
if (vma && vma->vm_start < end) {
if (start < vma->vm_start)
start = vma->vm_start;
if (end > vma->vm_end)
end = vma->vm_end;
flush_cache_user_range(vma, start, end);
}
up_read(&mm->mmap_sem);
}
/*
* Handle all unrecognised system calls.
* 0x9f0000 - 0x9fffff are some more esoteric system calls
*/
#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
asmlinkage int arm_syscall(int no, struct pt_regs *regs)
{
struct thread_info *thread = current_thread_info();
siginfo_t info;
if ((no >> 16) != (__ARM_NR_BASE>> 16))
return bad_syscall(no, regs);
switch (no & 0xffff) {
case 0: /* branch through 0 */
info.si_signo = SIGSEGV;
info.si_errno = 0;
info.si_code = SEGV_MAPERR;
info.si_addr = NULL;
arm_notify_die("branch through zero", regs, &info, 0, 0);
return 0;
case NR(breakpoint): /* SWI BREAK_POINT */
regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
ptrace_break(current, regs);
return regs->ARM_r0;
/*
* Flush a region from virtual address 'r0' to virtual address 'r1'
* _exclusive_. There is no alignment requirement on either address;
* user space does not need to know the hardware cache layout.
*
* r2 contains flags. It should ALWAYS be passed as ZERO until it
* is defined to be something else. For now we ignore it, but may
* the fires of hell burn in your belly if you break this rule. ;)
*
* (at a later date, we may want to allow this call to not flush
* various aspects of the cache. Passing '0' will guarantee that
* everything necessary gets flushed to maintain consistency in
* the specified region).
*/
case NR(cacheflush):
do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
return 0;
case NR(usr26):
if (!(elf_hwcap & HWCAP_26BIT))
break;
regs->ARM_cpsr &= ~MODE32_BIT;
return regs->ARM_r0;
case NR(usr32):
if (!(elf_hwcap & HWCAP_26BIT))
break;
regs->ARM_cpsr |= MODE32_BIT;
return regs->ARM_r0;
case NR(set_tls):
thread->tp_value = regs->ARM_r0;
if (tls_emu)
return 0;
if (has_tls_reg) {
asm ("mcr p15, 0, %0, c13, c0, 3"
: : "r" (regs->ARM_r0));
} else {
/*
* User space must never try to access this directly.
* Expect your app to break eventually if you do so.
* The user helper at 0xffff0fe0 must be used instead.
* (see entry-armv.S for details)
*/
*((unsigned int *)0xffff0ff0) = regs->ARM_r0;
}
return 0;
#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
/*
* Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
* Return zero in r0 if *MEM was changed or non-zero if no exchange
* happened. Also set the user C flag accordingly.
* If access permissions have to be fixed up then non-zero is
* returned and the operation has to be re-attempted.
*
* *NOTE*: This is a ghost syscall private to the kernel. Only the
* __kuser_cmpxchg code in entry-armv.S should be aware of its
* existence. Don't ever use this from user code.
*/
case NR(cmpxchg):
for (;;) {
extern void do_DataAbort(unsigned long addr, unsigned int fsr,
struct pt_regs *regs);
unsigned long val;
unsigned long addr = regs->ARM_r2;
struct mm_struct *mm = current->mm;
pgd_t *pgd; pmd_t *pmd; pte_t *pte;
spinlock_t *ptl;
regs->ARM_cpsr &= ~PSR_C_BIT;
down_read(&mm->mmap_sem);
pgd = pgd_offset(mm, addr);
if (!pgd_present(*pgd))
goto bad_access;
pmd = pmd_offset(pgd, addr);
if (!pmd_present(*pmd))
goto bad_access;
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
if (!pte_present(*pte) || !pte_dirty(*pte)) {
pte_unmap_unlock(pte, ptl);
goto bad_access;
}
val = *(unsigned long *)addr;
val -= regs->ARM_r0;
if (val == 0) {
*(unsigned long *)addr = regs->ARM_r1;
regs->ARM_cpsr |= PSR_C_BIT;
}
pte_unmap_unlock(pte, ptl);
up_read(&mm->mmap_sem);
return val;
bad_access:
up_read(&mm->mmap_sem);
/* simulate a write access fault */
do_DataAbort(addr, 15 + (1 << 11), regs);
}
#endif
default:
/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
if not implemented, rather than raising SIGILL. This
way the calling program can gracefully determine whether
a feature is supported. */
if ((no & 0xffff) <= 0x7ff)
return -ENOSYS;
break;
}
#ifdef CONFIG_DEBUG_USER
/*
* experience shows that these seem to indicate that
* something catastrophic has happened
*/
if (user_debug & UDBG_SYSCALL) {
printk("[%d] %s: arm syscall %d\n",
task_pid_nr(current), current->comm, no);
dump_instr("", regs);
if (user_mode(regs)) {
__show_regs(regs);
c_backtrace(regs->ARM_fp, processor_mode(regs));
}
}
#endif
info.si_signo = SIGILL;
info.si_errno = 0;
info.si_code = ILL_ILLTRP;
info.si_addr = (void __user *)instruction_pointer(regs) -
(thumb_mode(regs) ? 2 : 4);
arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
return 0;
}
#ifdef CONFIG_TLS_REG_EMUL
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-30 05:08:33 +08:00
/*
* We might be running on an ARMv6+ processor which should have the TLS
* register but for some reason we can't use it, or maybe an SMP system
* using a pre-ARMv6 processor (there are apparently a few prototypes like
* that in existence) and therefore access to that register must be
* emulated.
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-30 05:08:33 +08:00
*/
static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
{
int reg = (instr >> 12) & 15;
if (reg == 15)
return 1;
regs->uregs[reg] = current_thread_info()->tp_value;
regs->ARM_pc += 4;
return 0;
}
static struct undef_hook arm_mrc_hook = {
.instr_mask = 0x0fff0fff,
.instr_val = 0x0e1d0f70,
.cpsr_mask = PSR_T_BIT,
.cpsr_val = 0,
.fn = get_tp_trap,
};
static int __init arm_mrc_hook_init(void)
{
register_undef_hook(&arm_mrc_hook);
return 0;
}
late_initcall(arm_mrc_hook_init);
#endif
void __bad_xchg(volatile void *ptr, int size)
{
printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
__builtin_return_address(0), ptr, size);
BUG();
}
EXPORT_SYMBOL(__bad_xchg);
/*
* A data abort trap was taken, but we did not handle the instruction.
* Try to abort the user program, or panic if it was the kernel.
*/
asmlinkage void
baddataabort(int code, unsigned long instr, struct pt_regs *regs)
{
unsigned long addr = instruction_pointer(regs);
siginfo_t info;
#ifdef CONFIG_DEBUG_USER
if (user_debug & UDBG_BADABORT) {
printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
task_pid_nr(current), current->comm, code, instr);
dump_instr(KERN_ERR, regs);
show_pte(current->mm, addr);
}
#endif
info.si_signo = SIGILL;
info.si_errno = 0;
info.si_code = ILL_ILLOPC;
info.si_addr = (void __user *)addr;
arm_notify_die("unknown data abort code", regs, &info, instr, 0);
}
void __attribute__((noreturn)) __bug(const char *file, int line)
{
printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
*(int *)0 = 0;
/* Avoid "noreturn function does return" */
for (;;);
}
EXPORT_SYMBOL(__bug);
void __readwrite_bug(const char *fn)
{
printk("%s called, but not implemented\n", fn);
BUG();
}
EXPORT_SYMBOL(__readwrite_bug);
void __pte_error(const char *file, int line, unsigned long val)
{
printk("%s:%d: bad pte %08lx.\n", file, line, val);
}
void __pmd_error(const char *file, int line, unsigned long val)
{
printk("%s:%d: bad pmd %08lx.\n", file, line, val);
}
void __pgd_error(const char *file, int line, unsigned long val)
{
printk("%s:%d: bad pgd %08lx.\n", file, line, val);
}
asmlinkage void __div0(void)
{
printk("Division by zero in kernel.\n");
dump_stack();
}
EXPORT_SYMBOL(__div0);
void abort(void)
{
BUG();
/* if that doesn't kill us, halt */
panic("Oops failed to kill thread");
}
EXPORT_SYMBOL(abort);
void __init trap_init(void)
{
return;
}
static void __init kuser_get_tls_init(unsigned long vectors)
{
/*
* vectors + 0xfe0 = __kuser_get_tls
* vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
*/
if (tls_emu || has_tls_reg)
memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
}
void __init early_trap_init(void)
{
unsigned long vectors = CONFIG_VECTORS_BASE;
extern char __stubs_start[], __stubs_end[];
extern char __vectors_start[], __vectors_end[];
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-30 05:08:33 +08:00
extern char __kuser_helper_start[], __kuser_helper_end[];
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
/*
[PATCH] ARM: 2651/3: kernel helpers for NPTL support Patch from Nicolas Pitre This patch entirely reworks the kernel assistance for NPTL on ARM. In particular this provides an efficient way to retrieve the TLS value and perform atomic operations without any instruction emulation nor special system call. This even allows for pre ARMv6 binaries to be forward compatible with SMP systems without any penalty. The problematic and performance critical operations are performed through segment of kernel provided user code reachable from user space at a fixed address in kernel memory. Those fixed entry points are within the vector page so we basically get it for free as no extra memory page is required and nothing else may be mapped at that location anyway. This is different from (but doesn't preclude) a full blown VDSO implementation, however a VDSO would prevent some assembly tricks with constants that allows for efficient branching to those code segments. And since those code segments only use a few cycles before returning to user code, the overhead of a VDSO far call would add a significant overhead to such minimalistic operations. The ARM_NR_set_tls syscall also changed number. This is done for two reasons: 1) this patch changes the way the TLS value was previously meant to be retrieved, therefore we ensure whatever library using the old way gets fixed (they only exist in private tree at the moment since the NPTL work is still progressing). 2) the previous number was allocated in a range causing an undefined instruction trap on kernels not supporting that syscall and it was determined that allocating it in a range returning -ENOSYS would be much nicer for libraries trying to determine if the feature is present or not. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-04-30 05:08:33 +08:00
* Copy the vectors, stubs and kuser helpers (in entry-armv.S)
* into the vector page, mapped at 0xffff0000, and ensure these
* are visible to the instruction stream.
*/
memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
/*
* Do processor specific fixups for the kuser helpers
*/
kuser_get_tls_init(vectors);
/*
* Copy signal return handlers into the vector page, and
* set sigreturn to be a pointer to these.
*/
memcpy((void *)KERN_SIGRETURN_CODE, sigreturn_codes,
sizeof(sigreturn_codes));
memcpy((void *)KERN_RESTART_CODE, syscall_restart_code,
sizeof(syscall_restart_code));
flush_icache_range(vectors, vectors + PAGE_SIZE);
modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
}