Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We currently have 2 commonly used methods for switching ISA within
assembly code, then restoring the original ISA.
1) Using a pair of .set push & .set pop directives. For example:
.set push
.set mips32r2
<some_insn>
.set pop
2) Using .set mips0 to restore the ISA originally specified on the
command line. For example:
.set mips32r2
<some_insn>
.set mips0
Unfortunately method 2 does not work with nanoMIPS toolchains, where the
assembler rejects the .set mips0 directive like so:
Error: cannot change ISA from nanoMIPS to mips0
In preparation for supporting nanoMIPS builds, switch all instances of
method 2 in generic non-platform-specific code to use push & pop as in
method 1 instead. The .set push & .set pop is arguably cleaner anyway,
and if nothing else it's good to consistently use one method.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21037/
Cc: linux-mips@linux-mips.org
The GCC_OFF12_ASM macro is used for 12-bit immediate constrains
but we will also use it for 9-bit constrains on MIPS R6 so we
rename it to something more appropriate.
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Fix the issue with the ISA bit being lost in fixups that jump to labels
placed just before a section switch. Such a switch leads to the ISA bit
being lost, because GAS concludes there is no code that follows and
therefore the label refers to data. Use the `.insn' pseudo-op to
convince the tool this is not the case.
This lack of label annotation leads to microMIPS compilation errors
like:
mips-linux-gnu-ld: arch/mips/built-in.o: .fixup+0x3b8: Unsupported jump between ISA modes; consider recompiling with interlinking enabled.
mips-linux-gnu-ld: final link failed: Bad value
Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8483/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
In the microMIPS encoding some memory access instructions have their
immediate offset reduced to 12 bits only. That does not match the GCC
`R' constraint we use in some places to satisfy the requirement,
resulting in build failures like this:
{standard input}: Assembler messages:
{standard input}:720: Error: macro used $at after ".set noat"
{standard input}:720: Warning: macro instruction expanded into multiple instructions
Fix the problem by defining a macro, `GCC_OFF12_ASM', that expands to
the right constraint depending on whether microMIPS or standard MIPS
code is produced. Also apply the fix to where `m' is used as in the
worst case this change does nothing, e.g. where the pointer was already
in a register such as a function argument and no further offset was
requested, and in the best case it avoids an extraneous sequence of up
to two instructions to load the high 20 bits of the address in the LL/SC
loop. This reduces the risk of lock contention that is the higher the
more instructions there are in the critical section between LL and SC.
Strictly speaking we could just bulk-replace `R' with `ZC' as the latter
constraint adjusts automatically depending on the ISA selected.
However it was only introduced with GCC 4.9 and we keep supporing older
compilers for the standard MIPS configuration, hence the slightly more
complicated approach I chose.
The choice of a zero-argument function-like rather than an object-like
macro was made so that it does not look like a function call taking the
C expression used for the constraint as an argument. This is so as not
to confuse the reader or formatting checkers like `checkpatch.pl' and
follows previous practice.
Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8482/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
With binutils 2.24 the attempt to switch with microMIPS mode to MIPS III
mode through .set mips3 results in *lots* of warnings like
{standard input}: Assembler messages:
{standard input}:397: Warning: the 64-bit MIPS architecture does not support the `smartmips' extension
during a kernel build. Fixed by using .set arch=r4000 instead.
This breaks support for building the kernel with binutils 2.13 which
was supported for 32 bit kernels only anyway and 2.14 which was a bad
vintage for MIPS anyway.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Use LLE/SCE instructions for performing an address translation for
userspace when EVA is enabled.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Having received another series of whitespace patches I decided to do this
once and for all rather than dealing with this kind of patches trickling
in forever.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
