sparc/kernel/wuf.S

3  * wuf.S: Window underflow trap handler for the Sparc.
53 	 *      1  2  3  4     <--  Window number
57 	 *      O == the window that execution was in when
61 	 *           window
63 	 *      W == this window is the one which is now invalid
67 	 *      I == this window will be the invalid one when we
73 	/* On 7-window Sparc the boot code patches fnwin_patch1
83 	/* LOCATION: Window 'T' */
86 	 * the proper window off of the stack.
93 	wr	%twin_tmp1, 0x0, %wim	/* Make window 'I' invalid */
97 	 restore	%g0, %g0, %g0		/* Restore to window 'O' */
100 	 * 'over restore' sorta speak and just grab the window
104 	/* LOCATION: Window 'O' */
108 	/* LOCATION: Window 'W' */
117 	/* LOCATION: Window 'T' */
129 	/* LOCATION: Window 'O' */
131 	restore	%g0, %g0, %g0		/* Restore to window 'W' */
133 	/* LOCATION: Window 'W' */
142 	/* LOCATION: Window 'W' */
145 	 * to the trap window and call c-code to deal with this.
162 	/* LOCATION: Window 'O' */
164 	rd	%psr, %g3		/* Read %psr in live user window */
169 	/* LOCATION: Window 'T' */
182 	/* Fix users window mask and buffer save count. */
185 	st	%g5, [%curptr + TI_UWINMASK]		! one live user window still
197 	/* LOCATION: Window 'W' */
200 	 * window and fall through to the finish up routine.
205 	save	%g0, %g0, %g0		/* Save to window 'O' */
206 	save	%g0, %g0, %g0		/* Save to window 'T' */
209 	/* LOCATION: Window 'T' */
212 	/* LOCATION: Window 'T' */
221 	 * mappings.  Note that unlike the window overflow handler
224 	 * an invalid window which will be loaded, and this means
225 	 * that until we actually load the window up we are free
229 	 * if the area at %sp is user readable and the window still
235 	 * Contrary to the arch-specific window overflow stack
237 	 * any of the local registers they want to as this window
240 	 * 'someone elses' window possibly.
245 	/* LOCATION: Window 'W' */
280 	/* LOCATION: Window 'T' */
305 	/* Did I ever tell you about my window lobotomy?
307 	 * to be in window 'W' so make it happy or else