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authorMax Filippov <jcmvbkbc@gmail.com>2014-08-06 23:03:01 +0200
committerMax Filippov <jcmvbkbc@gmail.com>2014-08-14 09:59:32 +0200
commit3cfc096e4c4fbc234634cf8a30d40348a25fc9ba (patch)
treeb97d650f595268a33c0023bfbe407922e7c3f6b2 /arch/xtensa
parentxtensa: fix a6 and a7 handling in fast_syscall_xtensa (diff)
downloadlinux-3cfc096e4c4fbc234634cf8a30d40348a25fc9ba.tar.xz
linux-3cfc096e4c4fbc234634cf8a30d40348a25fc9ba.zip
xtensa: don't allow overflow/underflow on unaligned stack
Double exceptions that happen during register window overflow/underflow are handled in the topmost stack frame, as if it was the only exception that occured. However unaligned access exception handler is special because it needs to analyze instruction that caused the exception, but the userspace instruction that triggered window exception is completely irrelevant. Unaligned data access is rather normal in the generic userspace code, but stack pointer manipulation must always be done by architecture-aware code and thus unaligned stack means a serious problem anyway. Use the default unaligned access handler that raises SIGBUS in case of unaligned access in window overflow/underflow handler. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'arch/xtensa')
-rw-r--r--arch/xtensa/kernel/traps.c5
-rw-r--r--arch/xtensa/kernel/vectors.S8
-rw-r--r--arch/xtensa/kernel/vmlinux.lds.S4
3 files changed, 10 insertions, 7 deletions
diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
index eebbfd8c26fc..9d2f45f010ef 100644
--- a/arch/xtensa/kernel/traps.c
+++ b/arch/xtensa/kernel/traps.c
@@ -101,9 +101,8 @@ static dispatch_init_table_t __initdata dispatch_init_table[] = {
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
#ifdef CONFIG_XTENSA_UNALIGNED_USER
{ EXCCAUSE_UNALIGNED, USER, fast_unaligned },
-#else
-{ EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
#endif
+{ EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
{ EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
#endif
#ifdef CONFIG_MMU
@@ -264,7 +263,6 @@ do_illegal_instruction(struct pt_regs *regs)
*/
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
-#ifndef CONFIG_XTENSA_UNALIGNED_USER
void
do_unaligned_user (struct pt_regs *regs)
{
@@ -286,7 +284,6 @@ do_unaligned_user (struct pt_regs *regs)
}
#endif
-#endif
void
do_debug(struct pt_regs *regs)
diff --git a/arch/xtensa/kernel/vectors.S b/arch/xtensa/kernel/vectors.S
index 8453e6e39895..1b397a902292 100644
--- a/arch/xtensa/kernel/vectors.S
+++ b/arch/xtensa/kernel/vectors.S
@@ -454,8 +454,14 @@ _DoubleExceptionVector_WindowOverflow:
s32i a0, a2, PT_DEPC
_DoubleExceptionVector_handle_exception:
+ addi a0, a0, -EXCCAUSE_UNALIGNED
+ beqz a0, 2f
addx4 a0, a0, a3
- l32i a0, a0, EXC_TABLE_FAST_USER
+ l32i a0, a0, EXC_TABLE_FAST_USER + 4 * EXCCAUSE_UNALIGNED
+ xsr a3, excsave1
+ jx a0
+2:
+ movi a0, user_exception
xsr a3, excsave1
jx a0
diff --git a/arch/xtensa/kernel/vmlinux.lds.S b/arch/xtensa/kernel/vmlinux.lds.S
index d16db6df86f8..fc1bc2ba8d5d 100644
--- a/arch/xtensa/kernel/vmlinux.lds.S
+++ b/arch/xtensa/kernel/vmlinux.lds.S
@@ -269,13 +269,13 @@ SECTIONS
.UserExceptionVector.literal)
SECTION_VECTOR (_DoubleExceptionVector_literal,
.DoubleExceptionVector.literal,
- DOUBLEEXC_VECTOR_VADDR - 40,
+ DOUBLEEXC_VECTOR_VADDR - 48,
SIZEOF(.UserExceptionVector.text),
.UserExceptionVector.text)
SECTION_VECTOR (_DoubleExceptionVector_text,
.DoubleExceptionVector.text,
DOUBLEEXC_VECTOR_VADDR,
- 40,
+ 48,
.DoubleExceptionVector.literal)
. = (LOADADDR( .DoubleExceptionVector.text ) + SIZEOF( .DoubleExceptionVector.text ) + 3) & ~ 3;