| From 40507bf199440082ed69b777986d50c31efe2520 Mon Sep 17 00:00:00 2001 |
| From: Max Filippov <jcmvbkbc@gmail.com> |
| 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 <jcmvbkbc@gmail.com> |
| 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 <jcmvbkbc@gmail.com> |
| --- |
| 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 4d451c8..ef0703f 100644 |
| --- a/libgcc/config/xtensa/lib2funcs.S |
| +++ b/libgcc/config/xtensa/lib2funcs.S |
| @@ -34,10 +34,29 @@ 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 |
| #endif |
| |
| @@ -61,10 +80,7 @@ __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 |
| |
