| Message ID | 1482320454-5731-1-git-send-email-abrodkin@synopsys.com |
|---|---|
| State | New |
| Headers | show |
On 12/21/2016 03:40 AM, Alexey Brodkin wrote: > This enables misaligned access handling even in kernel mode. > Some wireless drivers (ath9k-htc and mt7601u) use misaligned accesses > here and there and to cope with that without fixing stuff in the drivers > we're just gracefully handling it on ARC. > > Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> > Cc: John Crispin <john@phrozen.org> > --- > arch/arc/kernel/unaligned.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c > index abd961f3e763..58b7415e47ca 100644 > --- a/arch/arc/kernel/unaligned.c > +++ b/arch/arc/kernel/unaligned.c > @@ -205,8 +205,8 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs, > struct disasm_state state; > char buf[TASK_COMM_LEN]; > > - /* handle user mode only and only if enabled by sysadmin */ > - if (!user_mode(regs) || !unaligned_enabled) > + /* handle only if enabled by sysadmin */ > + if (!unaligned_enabled) This in theory seems OK but AFAIKR we discussed this internally for STAR 9000974739- [openwrt/AXS101] unaligned access on connection of the first wireless client One of the crash logs had Interrupt Active while failing to emulate unaligned access - despite this patch. > [ECR ]: 0x00230400 => Misaligned r/w from 0x9e67a22b > [ 51.630000] [EFA ]: 0x9e67a22b > [ 51.630000] [BLINK ]: br_multicast_add_group+0x246/0x284 > [ 51.630000] [ERET ]: br_multicast_add_group+0xae/0x284 > [ 51.650000] [STAT32]: 0x0000020e : K A1 E2 E1 ^^^^ It seemed to me at the time that allowing this from kernel mode might require more things - like not allowing preemption or disabling further interrupts ? I looked in CRM but can't find more details - do u remember ! Can we try and reproduce that new-issue-after-patch or perhaps just add this patch as it is and deal with any fallouts later ? -Vineet > return 1; > > if (no_unaligned_warning) { >
diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c index abd961f3e763..58b7415e47ca 100644 --- a/arch/arc/kernel/unaligned.c +++ b/arch/arc/kernel/unaligned.c @@ -205,8 +205,8 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs, struct disasm_state state; char buf[TASK_COMM_LEN]; - /* handle user mode only and only if enabled by sysadmin */ - if (!user_mode(regs) || !unaligned_enabled) + /* handle only if enabled by sysadmin */ + if (!unaligned_enabled) return 1; if (no_unaligned_warning) {
This enables misaligned access handling even in kernel mode. Some wireless drivers (ath9k-htc and mt7601u) use misaligned accesses here and there and to cope with that without fixing stuff in the drivers we're just gracefully handling it on ARC. Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: John Crispin <john@phrozen.org> --- arch/arc/kernel/unaligned.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)