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| author | Max Filippov <jcmvbkbc@gmail.com> | 2014-08-07 01:03:01 +0400 |
|---|---|---|
| committer | Max Filippov <jcmvbkbc@gmail.com> | 2014-08-14 11:59:32 +0400 |
| commit | 3cfc096e4c4fbc234634cf8a30d40348a25fc9ba (patch) | |
| tree | b97d650f595268a33c0023bfbe407922e7c3f6b2 /arch/xtensa | |
| parent | d1b6ba82a50cecf94be540a3a153aa89d97511a0 (diff) | |
| download | lwn-3cfc096e4c4fbc234634cf8a30d40348a25fc9ba.tar.gz lwn-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.c | 5 | ||||
| -rw-r--r-- | arch/xtensa/kernel/vectors.S | 8 | ||||
| -rw-r--r-- | arch/xtensa/kernel/vmlinux.lds.S | 4 |
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; |