xtensa: rename PT_SIZE to PT_KERNEL_SIZE

PT_SIZE is used by the xtensa port to designate kernel exception frame
size. In preparation for struct pt_regs size change rename PT_SIZE to
PT_KERNEL_SIZE for clarity and change its definition to always cover
only the kernel exception frame.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

arch/xtensa/kernel/asm-offsets.c

@@ -63,7 +63,7 @@ int main(void)
 	DEFINE(PT_AREG15, offsetof (struct pt_regs, areg[15]));
 	DEFINE(PT_WINDOWBASE, offsetof (struct pt_regs, windowbase));
 	DEFINE(PT_WINDOWSTART, offsetof(struct pt_regs, windowstart));
-	DEFINE(PT_SIZE, sizeof(struct pt_regs));
+	DEFINE(PT_KERNEL_SIZE, offsetof(struct pt_regs, areg[16]));
 	DEFINE(PT_AREG_END, offsetof (struct pt_regs, areg[XCHAL_NUM_AREGS]));
 	DEFINE(PT_USER_SIZE, offsetof(struct pt_regs, areg[XCHAL_NUM_AREGS]));
 	DEFINE(PT_XTREGS_OPT, offsetof(struct pt_regs, xtregs_opt));

arch/xtensa/kernel/entry.S

@@ -341,8 +341,8 @@ KABI_W	_bbsi.l	a2, 3, 1f
 	/* Copy spill slots of a0 and a1 to imitate movsp
 	 * in order to keep exception stack continuous
 	 */
-	l32i	a3, a1, PT_SIZE
-	l32i	a0, a1, PT_SIZE + 4
+	l32i	a3, a1, PT_KERNEL_SIZE
+	l32i	a0, a1, PT_KERNEL_SIZE + 4
 	s32e	a3, a1, -16
 	s32e	a0, a1, -12
 #endif
@@ -706,12 +706,12 @@ kernel_exception_exit:
 	addi    a0, a1, -16
 	l32i    a3, a0, 0
 	l32i    a4, a0, 4
-	s32i    a3, a1, PT_SIZE+0
-	s32i    a4, a1, PT_SIZE+4
+	s32i    a3, a1, PT_KERNEL_SIZE + 0
+	s32i    a4, a1, PT_KERNEL_SIZE + 4
 	l32i    a3, a0, 8
 	l32i    a4, a0, 12
-	s32i    a3, a1, PT_SIZE+8
-	s32i    a4, a1, PT_SIZE+12
+	s32i    a3, a1, PT_KERNEL_SIZE + 8
+	s32i    a4, a1, PT_KERNEL_SIZE + 12
 
 	/* Common exception exit.
 	 * We restore the special register and the current window frame, and
@@ -821,7 +821,7 @@ ENTRY(debug_exception)
 
 	bbsi.l	a2, PS_UM_BIT, 2f	# jump if user mode
 
-	addi	a2, a1, -16-PT_SIZE	# assume kernel stack
+	addi	a2, a1, -16 - PT_KERNEL_SIZE	# assume kernel stack
 3:
 	l32i	a0, a3, DT_DEBUG_SAVE
 	s32i	a1, a2, PT_AREG1

arch/xtensa/kernel/vectors.S

@@ -88,7 +88,7 @@ ENDPROC(_UserExceptionVector)
  * Kernel exception vector. (Exceptions with PS.UM == 0, PS.EXCM == 0)
  *
  * We get this exception when we were already in kernel space.
- * We decrement the current stack pointer (kernel) by PT_SIZE and
+ * We decrement the current stack pointer (kernel) by PT_KERNEL_SIZE and
  * jump to the first-level handler associated with the exception cause.
  *
  * Note: we need to preserve space for the spill region.
@@ -100,7 +100,7 @@ ENTRY(_KernelExceptionVector)
 
 	xsr	a3, excsave1		# save a3, and get dispatch table
 	wsr	a2, depc		# save a2
-	addi	a2, a1, -16-PT_SIZE	# adjust stack pointer
+	addi	a2, a1, -16 - PT_KERNEL_SIZE	# adjust stack pointer
 	s32i	a0, a2, PT_AREG0	# save a0 to ESF
 	rsr	a0, exccause		# retrieve exception cause
 	s32i	a0, a2, PT_DEPC		# mark it as a regular exception