mirror of
https://github.com/torvalds/linux.git
synced 2024-11-08 13:11:45 +00:00
fe40c0af3c
Impact: introduce new uaccess exception handling framework
Introduce {get|put}_user_try and {get|put}_user_catch as new uaccess exception
handling framework.
{get|put}_user_try begins exception block and {get|put}_user_catch(err) ends
the block and gets err if an exception occured in {get|put}_user_ex() in the
block. The exception is stored thread_info->uaccess_err.
The example usage of this framework is below;
int func()
{
int err = 0;
get_user_try {
get_user_ex(...);
get_user_ex(...);
:
} get_user_catch(err);
return err;
}
Note: get_user_ex() is not clear the value when an exception occurs, it's
different from the behavior of __get_user(), but I think it doesn't matter.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
69 lines
1.5 KiB
C
69 lines
1.5 KiB
C
#include <linux/module.h>
|
|
#include <linux/spinlock.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
|
|
int fixup_exception(struct pt_regs *regs)
|
|
{
|
|
const struct exception_table_entry *fixup;
|
|
|
|
#ifdef CONFIG_PNPBIOS
|
|
if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
|
|
extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
|
|
extern u32 pnp_bios_is_utter_crap;
|
|
pnp_bios_is_utter_crap = 1;
|
|
printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
|
|
__asm__ volatile(
|
|
"movl %0, %%esp\n\t"
|
|
"jmp *%1\n\t"
|
|
: : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
|
|
panic("do_trap: can't hit this");
|
|
}
|
|
#endif
|
|
|
|
fixup = search_exception_tables(regs->ip);
|
|
if (fixup) {
|
|
/* If fixup is less than 16, it means uaccess error */
|
|
if (fixup->fixup < 16) {
|
|
current_thread_info()->uaccess_err = -EFAULT;
|
|
regs->ip += fixup->fixup;
|
|
return 1;
|
|
}
|
|
regs->ip = fixup->fixup;
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_X86_64
|
|
/*
|
|
* Need to defined our own search_extable on X86_64 to work around
|
|
* a B stepping K8 bug.
|
|
*/
|
|
const struct exception_table_entry *
|
|
search_extable(const struct exception_table_entry *first,
|
|
const struct exception_table_entry *last,
|
|
unsigned long value)
|
|
{
|
|
/* B stepping K8 bug */
|
|
if ((value >> 32) == 0)
|
|
value |= 0xffffffffUL << 32;
|
|
|
|
while (first <= last) {
|
|
const struct exception_table_entry *mid;
|
|
long diff;
|
|
|
|
mid = (last - first) / 2 + first;
|
|
diff = mid->insn - value;
|
|
if (diff == 0)
|
|
return mid;
|
|
else if (diff < 0)
|
|
first = mid+1;
|
|
else
|
|
last = mid-1;
|
|
}
|
|
return NULL;
|
|
}
|
|
#endif
|