| From 3251f1e27a5a17f0efd436cfd1e7b9896cfab0a0 Mon Sep 17 00:00:00 2001 |
| From: Max Filippov <jcmvbkbc@gmail.com> |
| Date: Wed, 30 Oct 2013 16:18:25 +0400 |
| Subject: xtensa: save current register frame in fast_syscall_spill_registers_fixup |
| |
| From: Max Filippov <jcmvbkbc@gmail.com> |
| |
| commit 3251f1e27a5a17f0efd436cfd1e7b9896cfab0a0 upstream. |
| |
| We need it saved because it contains a3 where we track which register |
| windows we still need to spill, and fixup handler may call C exception |
| handlers. Also fix comments. |
| |
| Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/xtensa/kernel/entry.S | 12 ++++++++++++ |
| 1 file changed, 12 insertions(+) |
| |
| --- a/arch/xtensa/kernel/entry.S |
| +++ b/arch/xtensa/kernel/entry.S |
| @@ -1117,6 +1117,13 @@ ENDPROC(fast_syscall_spill_registers) |
| * We basically restore WINDOWBASE and WINDOWSTART to the condition when |
| * we entered the spill routine and jump to the user exception handler. |
| * |
| + * Note that we only need to restore the bits in windowstart that have not |
| + * been spilled yet by the _spill_register routine. Luckily, a3 contains a |
| + * rotated windowstart with only those bits set for frames that haven't been |
| + * spilled yet. Because a3 is rotated such that bit 0 represents the register |
| + * frame for the current windowbase - 1, we need to rotate a3 left by the |
| + * value of the current windowbase + 1 and move it to windowstart. |
| + * |
| * a0: value of depc, original value in depc |
| * a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE |
| * a3: exctable, original value in excsave1 |
| @@ -1131,10 +1138,15 @@ ENTRY(fast_syscall_spill_registers_fixup |
| /* We need to make sure the current registers (a0-a3) are preserved. |
| * To do this, we simply set the bit for the current window frame |
| * in WS, so that the exception handlers save them to the task stack. |
| + * |
| + * Note: we use a3 to set the windowbase, so we take a special care |
| + * of it, saving it in the original _spill_registers frame across |
| + * the exception handler call. |
| */ |
| |
| xsr a3, excsave1 # get spill-mask |
| slli a3, a3, 1 # shift left by one |
| + addi a3, a3, 1 # set the bit for the current window frame |
| |
| slli a2, a3, 32-WSBITS |
| src a2, a3, a2 # a2 = xxwww1yyxxxwww1yy...... |
