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authorChris Zankel <chris@zankel.net>2014-01-28 22:09:51 -0800
committerChris Zankel <chris@zankel.net>2014-01-29 13:47:26 -0800
commitc0e50d41126e4786d9cf1105bdf783e55c99f915 (patch)
treea4b3b7cfe0e0d8fe23008b5c44a5d4ff43081738 /arch/xtensa
parent6b5a1f74e50170e64104135490dc32b657483594 (diff)
xtensa: fix fast_syscall_spill_registers
The original implementation could clobber registers under certain conditions. The Xtensa processor architecture uses windowed registers and the original implementation was using a4 as a temporary register, which under certain conditions could be register a0 of the oldest window frame, and didn't always restore the content correctly. By moving the _spill_registers routine inside the fast system call, it frees up one more register (the return address is not required anymore) for the spill routine. Signed-off-by: Chris Zankel <chris@zankel.net>
Diffstat (limited to 'arch/xtensa')
-rw-r--r--arch/xtensa/kernel/vectors.S2
-rw-r--r--arch/xtensa/kernel/xtensa_ksyms.c2
2 files changed, 1 insertions, 3 deletions
diff --git a/arch/xtensa/kernel/vectors.S b/arch/xtensa/kernel/vectors.S
index cb8fd44caabc..f9e1ec346e35 100644
--- a/arch/xtensa/kernel/vectors.S
+++ b/arch/xtensa/kernel/vectors.S
@@ -235,7 +235,7 @@ ENTRY(_DoubleExceptionVector)
/* Check for overflow/underflow exception, jump if overflow. */
- _bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow
+ bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow
/*
* Restart window underflow exception.
diff --git a/arch/xtensa/kernel/xtensa_ksyms.c b/arch/xtensa/kernel/xtensa_ksyms.c
index 74a60c7e085e..80b33ed51f31 100644
--- a/arch/xtensa/kernel/xtensa_ksyms.c
+++ b/arch/xtensa/kernel/xtensa_ksyms.c
@@ -122,9 +122,7 @@ EXPORT_SYMBOL(insw);
EXPORT_SYMBOL(insl);
extern long common_exception_return;
-extern long _spill_registers;
EXPORT_SYMBOL(common_exception_return);
-EXPORT_SYMBOL(_spill_registers);
#ifdef CONFIG_FUNCTION_TRACER
EXPORT_SYMBOL(_mcount);