You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
64 lines
1.3 KiB
64 lines
1.3 KiB
#include <machine/asm.h>
|
|
|
|
IMPORT(remaining_invocations)
|
|
IMPORT(origstate)
|
|
IMPORT(newstate)
|
|
|
|
#define JUNK 0xCC0FFEE0
|
|
|
|
#define COPY(dest, offset) \
|
|
mov $dest, %ebp ; \
|
|
mov 4*offset(%esp), %ebx ; \
|
|
mov %ebx, 4*offset(%ebp) ;
|
|
|
|
/* Copy the result of a pusha to dest. */
|
|
#define COPYA(dest) \
|
|
COPY(dest, 0); COPY(dest, 1); COPY(dest, 2); COPY(dest, 3); \
|
|
COPY(dest, 4); COPY(dest, 5); COPY(dest, 6); COPY(dest, 7);
|
|
|
|
/* void check_context_loop() */
|
|
ENTRY(check_context_loop)
|
|
/* Save original context so we can restore it. */
|
|
pusha
|
|
|
|
/* Put some junk in the registers.
|
|
* We want to junk the state, and junk it differently per reg,
|
|
* so it's likelier corruption is actually detected. We can't
|
|
* touch %esp but we can verify that it doesn't change from its
|
|
* current value.
|
|
*/
|
|
mov $JUNK+1, %eax
|
|
mov $JUNK+2, %ebx
|
|
mov $JUNK+3, %ecx
|
|
mov $JUNK+4, %edx
|
|
mov $JUNK+5, %ebp
|
|
mov $JUNK+6, %esi
|
|
mov $JUNK+7, %edi
|
|
|
|
/* Save the junked state so we can compare it. */
|
|
pusha
|
|
cont:
|
|
/* Check if we're done. */
|
|
cmpl $0, (_C_LABEL(remaining_invocations))
|
|
jz done
|
|
|
|
/* We're not done. */
|
|
|
|
/* Restart loop. */
|
|
jmp cont
|
|
|
|
done:
|
|
/* Save the junked, but should be unmodified state
|
|
* so we can copy it.
|
|
*/
|
|
pusha
|
|
COPYA(_C_LABEL(newstate));
|
|
popa
|
|
|
|
/* copy and restore junked state */
|
|
COPYA(_C_LABEL(origstate));
|
|
popa
|
|
|
|
/* restore original state and return */
|
|
popa
|
|
ret
|
|
|