From 05154174b369505238b759cf80d595d8cfc8c731 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Mon, 10 Aug 2015 21:35:20 +0300 Subject: [PATCH 1/3] xtensa: reimplement register spilling Spilling windowed registers in userspace is much easier, more portable, less error-prone and equally effective as in kernel. Now that register spilling syscall is considered obsolete in the xtensa linux kernel replace it with CALL12 followed by series of ENTRY in libgcc. 2015-08-18 Max Filippov libgcc/ * config/xtensa/lib2funcs.S (__xtensa_libgcc_window_spill): Use CALL12 followed by series of ENTRY to spill windowed registers. (__xtensa_nonlocal_goto): Call __xtensa_libgcc_window_spill instead of making linux spill syscall. Signed-off-by: Max Filippov --- Backported from: r226962 libgcc/config/xtensa/lib2funcs.S | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/libgcc/config/xtensa/lib2funcs.S b/libgcc/config/xtensa/lib2funcs.S index 3ac8c1d..2e678af 100644 --- a/libgcc/config/xtensa/lib2funcs.S +++ b/libgcc/config/xtensa/lib2funcs.S @@ -33,10 +33,29 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see .global __xtensa_libgcc_window_spill .type __xtensa_libgcc_window_spill,@function __xtensa_libgcc_window_spill: - entry sp, 32 - movi a2, 0 - syscall + entry sp, 48 +#if XCHAL_NUM_AREGS > 16 + call12 1f + retw + .align 4 +1: + .rept (XCHAL_NUM_AREGS - 24) / 12 + _entry sp, 48 + mov a12, a0 + .endr + _entry sp, 16 +#if XCHAL_NUM_AREGS % 12 == 0 + mov a4, a4 +#elif XCHAL_NUM_AREGS % 12 == 4 + mov a8, a8 +#elif XCHAL_NUM_AREGS % 12 == 8 + mov a12, a12 +#endif + retw +#else + mov a8, a8 retw +#endif .size __xtensa_libgcc_window_spill, .-__xtensa_libgcc_window_spill @@ -58,10 +77,7 @@ __xtensa_nonlocal_goto: entry sp, 32 /* Flush registers. */ - mov a5, a2 - movi a2, 0 - syscall - mov a2, a5 + call8 __xtensa_libgcc_window_spill /* Because the save area for a0-a3 is stored one frame below the one identified by a2, the only way to restore those -- 1.8.1.4