On Wed, Jun 16, 2021 at 01:31:52PM -0500, Eric W. Biederman wrote:
+.macro SAVE_SWITCH_STACK
+ DO_SWITCH_STACK
+1: ldl_l $1, TI_FLAGS($8)
+ bis $1, _TIF_ALLREGS_SAVED, $1
+ stl_c $1, TI_FLAGS($8)
+ beq $1, 2f
+.subsection 2
+2: br 1b
+.previous
+.endm
What the hell? *IF* you are going to go that way, at least put it into
->status, not ->flag - those are thread-synchronous and do not require that
kind of masturbation.
+.macro RESTORE_SWITCH_STACK
+1: ldl_l $1, TI_FLAGS($8)
+ bic $1, _TIF_ALLREGS_SAVED, $1
+ stl_c $1, TI_FLAGS($8)
+ beq $1, 2f
+.subsection 2
+2: br 1b
+.previous
+ UNDO_SWITCH_STACK
+.endm
Ditto. What do you need that flag for, anyway?
@@ -117,7 +117,13 @@ get_reg_addr(struct task_struct * task, unsigned long regno)
zero = 0;
addr = &zero;
} else {
- addr = task_stack_page(task) + regoff[regno];
+ int off = regoff[regno];
+ if (WARN_ON_ONCE((off < PT_REG(r0)) &&
+ !test_ti_thread_flag(task_thread_info(task),
+ TIF_ALLREGS_SAVED)))
+ addr = &zero;
+ else
+ addr = task_stack_page(task) + off;
A sanity check in slow path, buggering the hell out of a fast path?
