Messages in this thread | | | Date | Wed, 6 Jun 2012 16:31:50 +1000 | From | Greg Ungerer <> | Subject | Re: [PATCH] m68k: Use generic strncpy_from_user(), strlen_user(), and strnlen_user() |
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Hi Geert,
On 06/06/12 06:57, Geert Uytterhoeven wrote: > On Wed, May 30, 2012 at 4:04 PM, Philippe De Muyter<phdm@macqel.be> wrote: >> On Wed, May 30, 2012 at 01:20:02PM +0200, Geert Uytterhoeven wrote: >>> On Wed, May 30, 2012 at 12:22 PM, Philippe De Muyter<phdm@macqel.be> wrote: >>>> On Tue, May 29, 2012 at 11:33:36PM +0200, Geert Uytterhoeven wrote: >>>>> Signed-off-by: Geert Uytterhoeven<geert@linux-m68k.org> >>>>> --- >>>>> Do we also want >>>>> >>>>> select HAVE_EFFICIENT_UNALIGNED_ACCESS if (!COLDFIRE&& !M68000) >>>> >>>> Sorry, I did not follow what happened to unaligned accesses, but >>>> CPU32 family (at least 68340) crashes on unaligned accesses. >>> >>> We don't seem to have CONFIG_M68340 in arch/m68k/Kconfig.cpu? >> >> I have a local port here (but based on an ancient linux kernel, 2.6.2 IIRC) >> >>> But Freescale's website confirms both 68340 and 68360 are CPU32. >>> >>> arch/m68k/include/asm/unaligned.h assumes CPU32 (CONFIG_MCPU32) >>> can do unaligned accesses: >> >> That's not true. Accessing a 16- or 32-bit word at an odd address >> with a 68340 generates an Address Error Exception. I remember >> discovering a bug in the ppp kernel code because of that. >> >>> >>> #if defined(CONFIG_COLDFIRE) || defined(CONFIG_M68000) >>> #include<linux/unaligned/be_struct.h> >>> #include<linux/unaligned/le_byteshift.h> >>> #include<linux/unaligned/generic.h> >>> >>> #define get_unaligned __get_unaligned_be >>> #define put_unaligned __put_unaligned_be >>> >>> #else >>> /* >>> * The m68k can do unaligned accesses itself. >>> */ >>> #include<linux/unaligned/access_ok.h> >>> #include<linux/unaligned/generic.h> >>> >>> #define get_unaligned __get_unaligned_be >>> #define put_unaligned __put_unaligned_be >>> >>> #endif >>> >>> Is this wrong? >> >> I can't tell from reading just the lines above, but I think one should add >> "|| defined(CONFIG_MCPU32)" at the end of the if condition. > > Greg? > > If more CPUs cannot handle unaligned accesses, I propose to add > CONFIG_CPU_HAS_NO_UNALIGNED.
Yes, looks like that should have a "|| defined(CONFIG_CPU32)". (According to the CPU32 reference manual words and long words must be aligned on word boundaries.)
I think something like CONFIG_CPU_HAS_NO_UNALIGNED makes sense.
>> I also think that the Coldfire 5272 can do unaligned accesses, but I >> cannot test that at the moment.
According to the MCF5272 User Manual, "it supports misaligned data accesses ...". So it looks like it does.
Having a CONFIG_CPU_HAS_NO_UNALIGNED looks like a really good solution then. We need to be able select it as required on individual CPU types.
Regards Greg
------------------------------------------------------------------------ Greg Ungerer -- Principal Engineer EMAIL: gerg@snapgear.com SnapGear Group, McAfee PHONE: +61 7 3435 2888 8 Gardner Close FAX: +61 7 3217 5323 Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com
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