Without this fix the value of a0 spilled from the oldest live window is wrong if the newest window has only 4 live registers, because a4 in the newest window overlaps a0 in the oldest one.
This may be reproduced by invoking spill syscall after the following sequence of calls: 4 -> 12 -> 12 -> 4 on configuration with 32 physical registers. Cc: [email protected] Signed-off-by: Max Filippov <[email protected]> --- arch/xtensa/kernel/entry.S | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index 4dd391d..90c6fc6 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -1241,6 +1241,7 @@ ENTRY(_spill_registers) * Rotate ws right so that a4 = yyxxxwww1. */ + wsr a4, depc # save a4: we may need to spill it rsr a4, windowbase rsr a3, windowstart # a3 = xxxwww1yy ssr a4 # holds WB @@ -1271,6 +1272,7 @@ ENTRY(_spill_registers) rsr a3, windowbase add a3, a3, a4 + rsr a4, depc # restore a4 wsr a3, windowbase rsync -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
