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authorMax Filippov <jcmvbkbc@gmail.com>2015-07-16 10:41:02 +0300
committerSasha Levin <sasha.levin@oracle.com>2015-10-27 22:14:47 -0400
commitab0a85f0cb4fcf6390d223d53bddf9478a8a27f9 (patch)
treebff2ed048117617fbc7311c01476c7fcc8f99861
parentb8a64ee186718fd0cd6616c907a89254f6583d3a (diff)
downloadlinux-linaro-stable-ab0a85f0cb4fcf6390d223d53bddf9478a8a27f9.tar.gz
xtensa: fix kernel register spilling
[ Upstream commit 77d6273e79e3a86552fcf10cdd31a69b46ed2ce6 ] call12 can't be safely used as the first call in the inline function, because the compiler does not extend the stack frame of the bounding function accordingly, which may result in corruption of local variables. If a call needs to be done, do call8 first followed by call12. For pure assembly code in _switch_to increase stack frame size of the bounding function. Cc: stable@vger.kernel.org Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--arch/xtensa/include/asm/traps.h29
-rw-r--r--arch/xtensa/kernel/entry.S4
2 files changed, 21 insertions, 12 deletions
diff --git a/arch/xtensa/include/asm/traps.h b/arch/xtensa/include/asm/traps.h
index 677bfcf4ee5d..28f33a8b7f5f 100644
--- a/arch/xtensa/include/asm/traps.h
+++ b/arch/xtensa/include/asm/traps.h
@@ -25,30 +25,39 @@ static inline void spill_registers(void)
{
#if XCHAL_NUM_AREGS > 16
__asm__ __volatile__ (
- " call12 1f\n"
+ " call8 1f\n"
" _j 2f\n"
" retw\n"
" .align 4\n"
"1:\n"
+#if XCHAL_NUM_AREGS == 32
+ " _entry a1, 32\n"
+ " addi a8, a0, 3\n"
+ " _entry a1, 16\n"
+ " mov a12, a12\n"
+ " retw\n"
+#else
" _entry a1, 48\n"
- " addi a12, a0, 3\n"
-#if XCHAL_NUM_AREGS > 32
- " .rept (" __stringify(XCHAL_NUM_AREGS) " - 32) / 12\n"
+ " call12 1f\n"
+ " retw\n"
+ " .align 4\n"
+ "1:\n"
+ " .rept (" __stringify(XCHAL_NUM_AREGS) " - 16) / 12\n"
" _entry a1, 48\n"
" mov a12, a0\n"
" .endr\n"
-#endif
- " _entry a1, 48\n"
+ " _entry a1, 16\n"
#if XCHAL_NUM_AREGS % 12 == 0
- " mov a8, a8\n"
-#elif XCHAL_NUM_AREGS % 12 == 4
" mov a12, a12\n"
-#elif XCHAL_NUM_AREGS % 12 == 8
+#elif XCHAL_NUM_AREGS % 12 == 4
" mov a4, a4\n"
+#elif XCHAL_NUM_AREGS % 12 == 8
+ " mov a8, a8\n"
#endif
" retw\n"
+#endif
"2:\n"
- : : : "a12", "a13", "memory");
+ : : : "a8", "a9", "memory");
#else
__asm__ __volatile__ (
" mov a12, a12\n"
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 51e9877ced06..a2a902140c4e 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -1821,7 +1821,7 @@ ENDPROC(system_call)
mov a12, a0
.endr
#endif
- _entry a1, 48
+ _entry a1, 16
#if XCHAL_NUM_AREGS % 12 == 0
mov a8, a8
#elif XCHAL_NUM_AREGS % 12 == 4
@@ -1845,7 +1845,7 @@ ENDPROC(system_call)
ENTRY(_switch_to)
- entry a1, 16
+ entry a1, 48
mov a11, a3 # and 'next' (a3)