kernel.git/arch/arm/mm/alignment.c, branch linux-3.2.y

ARM: 8165/1: alignment: don't break misaligned NEON load/store

2014-11-05T20:27:46Z

commit 5ca918e5e3f9df4634077c06585c42bc6a8d699a upstream. The alignment fixup incorrectly decodes faulting ARM VLDn/VSTn instructions (where the optional alignment hint is given but incorrect) as LDR/STR, leading to register corruption. Detect these and correctly treat them as unhandled, so that userspace gets the fault it expects. Reported-by: Simon Hosie Signed-off-by: Robin Murphy Signed-off-by: Russell King Signed-off-by: Ben Hutchings

ARM: fix scheduling while atomic warning in alignment handling code

2013-03-20T15:03:17Z

commit b255188f90e2bade1bd11a986dd1ca4861869f4d upstream. Paolo Pisati reports that IPv6 triggers this warning: BUG: scheduling while atomic: swapper/0/0/0x40000100 Modules linked in: [] (unwind_backtrace+0x0/0xf0) from [] (__schedule_bug+0x48/0x5c) [] (__schedule_bug+0x48/0x5c) from [] (__schedule+0x700/0x740) [] (__schedule+0x700/0x740) from [] (__cond_resched+0x24/0x34) [] (__cond_resched+0x24/0x34) from [] (_cond_resched+0x3c/0x44) [] (_cond_resched+0x3c/0x44) from [] (do_alignment+0x178/0x78c) [] (do_alignment+0x178/0x78c) from [] (do_DataAbort+0x34/0x98) [] (do_DataAbort+0x34/0x98) from [] (__dabt_svc+0x40/0x60) Exception stack(0xc0763d70 to 0xc0763db8) 3d60: e97e805e e97e806e 2c000000 11000000 3d80: ea86bb00 0000002c 00000011 e97e807e c076d2a8 e97e805e e97e806e 0000002c 3da0: 3d000000 c0763dbc c04b98fc c02a8490 00000113 ffffffff [] (__dabt_svc+0x40/0x60) from [] (__csum_ipv6_magic+0x8/0xc8) Fix this by using probe_kernel_address() stead of __get_user(). Reported-by: Paolo Pisati Tested-by: Paolo Pisati Signed-off-by: Russell King Signed-off-by: Ben Hutchings

ARM: allow building alignment.c without PROC_FS

2011-10-01T19:08:54Z

The two functions cpu_is_v6_unaligned and safe_usermode are only defined when CONFIG_PROC_FS is enabled, but are used outside of the #ifdef. Signed-off-by: Arnd Bergmann Cc: Dave Martin

ARM: 7008/1: alignment: Make SIGBUS sent to userspace POSIXly correct

2011-08-09T07:42:39Z

With the UM_SIGNAL alignment fault mode, no siginfo structure is passed to userspace. POSIX specifies how siginfo_t should be populated for alignment faults, so this patch does just that: * si_signo = SIGBUS * si_code = BUS_ADRALN * si_addr = misaligned data address at which access was attempted Signed-off-by: Dave Martin Acked-by: Nicolas Pitre Acked-by: Kirill A. Shutemov Reviewed-by: Will Deacon Signed-off-by: Russell King

ARM: 7007/1: alignment: Prevent ignoring of faults with ARMv6 unaligned access model

2011-08-09T07:42:39Z

Currently, it's possible to set the kernel to ignore alignment faults when changing the alignment fault handling mode at runtime via /proc/sys/alignment, even though this is undesirable on ARMv6 and above, where it can result in infinite spins where an un-fixed- up instruction repeatedly faults. In addition, the kernel clobbers any alignment mode specified on the command-line if running on ARMv6 or above. This patch factors out the necessary safety check into a couple of new helper functions, and checks and modifies the fault handling mode as appropriate on boot and on writes to /proc/cpu/alignment. Prior to ARMv6, the behaviour is unchanged. For ARMv6 and above, the behaviour changes as follows: * Attempting to ignore faults on ARMv6 results in the mode being forced to UM_FIXUP instead. A warning is printed if this happened as a result of a write to /proc/cpu/alignment. The user's UM_WARN bit (if present) is still honoured. * An alignment= argument from the kernel command-line is now honoured, except that the kernel will modify the specified mode as described above. This is allows modes such as UM_SIGNAL and UM_WARN to be active immediately from boot, which is useful for debugging purposes. Signed-off-by: Dave Martin Acked-by: Nicolas Pitre Signed-off-by: Russell King

ARM: entry: avoid enabling interrupts in prefetch/data abort handlers

2011-07-02T09:56:00Z

Avoid enabling interrupts if the parent context had interrupts enabled in the abort handler assembly code, and move this into the breakpoint/ page/alignment fault handlers instead. This gets rid of some special-casing for the breakpoint fault handlers from the low level abort handler path. Acked-by: Will Deacon Signed-off-by: Russell King

ARM: 6401/1: plug a race in the alignment trap handler

2010-09-23T14:17:04Z

When the policy for user space is to ignore misaligned accesses from user space, the processor then performs a documented rotation on the accessed data. This is the result of the access being trapped, and the kernel disabling the alignment trap before returning to user space again. In kernel space we always want misaligned accesses to be fixed up. This is enforced by always re-enabling the alignment trap on every entry into kernel space from user space. No such re-enabling is performed when an exception occurs while already in kernel space as the alignment trap is always supposed to be enabled in that case. There is however a small race window when a misaligned access in user space is trapped and the alignment trap disabled, but the CPU didn't return to user space just yet. Any exception would be entered from kernel space at that point and the kernel would then execute with the alignment trap disabled. Thanks to Maxime Bizon for providing a test module that made this issue reproducible. Signed-off-by: Nicolas Pitre Signed-off-by: Russell King

ARM: 6268/1: ARMv6K and ARMv7 use fault statuses 3 and 6 as Access Flag fault

2010-07-27T09:48:41Z

Statuses 3 (0b00011) and 6 (0x00110) of DFSR are Access Flags faults on ARMv6K and ARMv7. Let's patch fsr_info[] at runtime if we are on ARMv7 or later. Unfortunately, we don't have runtime check for 'K' extension, so we can't check for it. Signed-off-by: Kirill A. Shutemov Signed-off-by: Russell King

ARM: 6269/1: Add 'code' parameter for hook_fault_code()

2010-07-27T09:48:34Z

Add one more parameter to hook_fault_code() to be able to set 'code' field of struct fsr_info. Signed-off-by: Kirill A. Shutemov Signed-off-by: Russell King

ARM: 6252/1: Use SIGBUS for unaligned access instead of SIGILL

2010-07-27T09:43:49Z

POSIX specify to use signal SIGBUS with code BUS_ADRALN for invalid address alignment. Signed-off-by: Kirill A. Shutemov Signed-off-by: Russell King