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In some cases the kernel needs to execute an instruction from the delay
slot of an emulated branch instruction. These cases include:
- Emulated floating point branch instructions (bc1[ft]l?) for systems
which don't include an FPU, or upon which the kernel is run with the
"nofpu" parameter.
- MIPSr6 systems running binaries targeting older revisions of the
architecture, which may include branch instructions whose encodings
are no longer valid in MIPSr6.
Executing instructions from such delay slots is done by writing the
instruction to memory followed by a trap, as part of an "emuframe", and
executing it. This avoids the requirement of an emulator for the entire
MIPS instruction set. Prior to this patch such emuframes are written to
the user stack and executed from there.
This patch moves FP branch delay emuframes off of the user stack and
into a per-mm page. Allocating a page per-mm leaves userland with access
to only what it had access to previously, and compared to other
solutions is relatively simple.
When a thread requires a delay slot emulation, it is allocated a frame.
A thread may only have one frame allocated at any one time, since it may
only ever be executing one instruction at any one time. In order to
ensure that we can free up allocated frame later, its index is recorded
in struct thread_struct. In the typical case, after executing the delay
slot instruction we'll execute a break instruction with the BRK_MEMU
code. This traps back to the kernel & leads to a call to do_dsemulret
which frees the allocated frame & moves the user PC back to the
instruction that would have executed following the emulated branch.
In some cases the delay slot instruction may be invalid, such as a
branch, or may trigger an exception. In these cases the BRK_MEMU break
instruction will not be hit. In order to ensure that frames are freed
this patch introduces dsemul_thread_cleanup() and calls it to free any
allocated frame upon thread exit. If the instruction generated an
exception & leads to a signal being delivered to the thread, or indeed
if a signal simply happens to be delivered to the thread whilst it is
executing from the struct emuframe, then we need to take care to exit
the frame appropriately. This is done by either rolling back the user PC
to the branch or advancing it to the continuation PC prior to signal
delivery, using dsemul_thread_rollback(). If this were not done then a
sigreturn would return to the struct emuframe, and if that frame had
meanwhile been used in response to an emulated branch instruction within
the signal handler then we would execute the wrong user code.
Whilst a user could theoretically place something like a compact branch
to self in a delay slot and cause their thread to become stuck in an
infinite loop with the frame never being deallocated, this would:
- Only affect the users single process.
- Be architecturally invalid since there would be a branch in the
delay slot, which is forbidden.
- Be extremely unlikely to happen by mistake, and provide a program
with no more ability to harm the system than a simple infinite loop
would.
If a thread requires a delay slot emulation & no frame is available to
it (ie. the process has enough other threads that all frames are
currently in use) then the thread joins a waitqueue. It will sleep until
a frame is freed by another thread in the process.
Since we now know whether a thread has an allocated frame due to our
tracking of its index, the cookie field of struct emuframe is removed as
we can be more certain whether we have a valid frame. Since a thread may
only ever have a single frame at any given time, the epc field of struct
emuframe is also removed & the PC to continue from is instead stored in
struct thread_struct. Together these changes simplify & shrink struct
emuframe somewhat, allowing twice as many frames to fit into the page
allocated for them.
The primary benefit of this patch is that we are now free to mark the
user stack non-executable where that is possible.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: Maciej Rozycki <maciej.rozycki@imgtec.com>
Cc: Faraz Shahbazker <faraz.shahbazker@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13764/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
(cherry picked from commit 432c6bacbd0c16ec210c43da411ccc3855c4c010)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
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commit 6533af4d4831c421cd9aa4dce7cfc19a3514cc09 upstream.
If a kernel doesn't support MSA context (ie. CONFIG_CPU_HAS_MSA=n) then
it will only keep 64 bits per FP register in thread context, and the
calls to set_fpr64 in restore_msa_extcontext will overrun the end of the
FP register context into the FCSR & MSACSR values. GCC 6.x has become
smart enough to detect this & complain like so:
arch/mips/kernel/signal.c: In function 'protected_restore_fp_context':
./arch/mips/include/asm/processor.h:114:17: error: array subscript is above array bounds [-Werror=array-bounds]
fpr->val##width[FPR_IDX(width, idx)] = val; \
~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
./arch/mips/include/asm/processor.h:118:1: note: in expansion of macro 'BUILD_FPR_ACCESS'
BUILD_FPR_ACCESS(64)
The only way to trigger this code to run would be for a program to set
up an artificial extended MSA context structure following a sigframe &
execute sigreturn. Whilst this doesn't allow a program to write to any
state that it couldn't already, it makes little sense to allow this
"restoration" of MSA context in a system that doesn't support MSA.
Fix this by killing a program with SIGSYS if it tries something as crazy
as "restoring" fake MSA context in this way, also fixing the build error
& allowing for most of restore_msa_extcontext to be optimised out of
kernels without support for MSA.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reported-by: Michal Toman <michal.toman@imgtec.com>
Fixes: bf82cb30c7e5 ("MIPS: Save MSA extended context around signals")
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Michal Toman <michal.toman@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13164/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 13eb192d10bcc9ac518d57356179071d603bcb4e upstream.
In microMIPS kernels, handle_signal() sets the isa16 mode bit in the
vdso address so that the sigreturn trampolines (which are offset from
the VDSO) get executed as microMIPS.
However commit ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
changed the offsets to come from the VDSO image, which already have the
isa16 mode bit set correctly since they're extracted from the VDSO
shared library symbol table.
Drop the isa16 mode bit handling from handle_signal() to fix sigreturn
for cores which support both microMIPS and normal MIPS. This doesn't fix
microMIPS only cores, since the VDSO is still built for normal MIPS, but
thats a separate problem.
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13348/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 6533af4d4831c421cd9aa4dce7cfc19a3514cc09 upstream.
If a kernel doesn't support MSA context (ie. CONFIG_CPU_HAS_MSA=n) then
it will only keep 64 bits per FP register in thread context, and the
calls to set_fpr64 in restore_msa_extcontext will overrun the end of the
FP register context into the FCSR & MSACSR values. GCC 6.x has become
smart enough to detect this & complain like so:
arch/mips/kernel/signal.c: In function 'protected_restore_fp_context':
./arch/mips/include/asm/processor.h:114:17: error: array subscript is above array bounds [-Werror=array-bounds]
fpr->val##width[FPR_IDX(width, idx)] = val; \
~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
./arch/mips/include/asm/processor.h:118:1: note: in expansion of macro 'BUILD_FPR_ACCESS'
BUILD_FPR_ACCESS(64)
The only way to trigger this code to run would be for a program to set
up an artificial extended MSA context structure following a sigframe &
execute sigreturn. Whilst this doesn't allow a program to write to any
state that it couldn't already, it makes little sense to allow this
"restoration" of MSA context in a system that doesn't support MSA.
Fix this by killing a program with SIGSYS if it tries something as crazy
as "restoring" fake MSA context in this way, also fixing the build error
& allowing for most of restore_msa_extcontext to be optimised out of
kernels without support for MSA.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reported-by: Michal Toman <michal.toman@imgtec.com>
Fixes: bf82cb30c7e5 ("MIPS: Save MSA extended context around signals")
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Michal Toman <michal.toman@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13164/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add an initial implementation of a proper (i.e. an ELF shared library)
VDSO. With this commit it does not export any symbols, it only replaces
the current signal return trampoline page. A later commit will add user
implementations of gettimeofday()/clock_gettime().
To support both new toolchains and old ones which don't generate ABI
flags section, we define its content manually and then use a tool
(genvdso) to patch up the section to have the correct name and type.
genvdso also extracts symbol offsets ({,rt_}sigreturn) needed by the
kernel, and generates a C file containing a "struct mips_vdso_image"
containing both the VDSO data and these offsets. This C file is
compiled into the kernel.
On 64-bit kernels we require a different VDSO for each supported ABI,
so we may build up to 3 different VDSOs. The VDSO to use is selected by
the mips_abi structure.
A kernel/user shared data page is created and mapped below the VDSO
image. This is currently empty, but will be used by the user time
function implementations which are added later.
[markos.chandras@imgtec.com:
- Add more comments
- Move abi detection in genvdso.h since it's the get_symbol function
that needs it.
- Add an R6 specific way to calculate the base address of VDSO in order
to avoid the branch instruction which affects performance.
- Do not patch .gnu.attributes since it's not needed for dynamic linking.
- Simplify Makefile a little bit.
- checkpatch fixes
- Restrict VDSO support for binutils < 2.25 for pre-R6
- Include atomic64.h for O32 variant on MIPS64]
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11337/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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It is desirable for signal handlers to be allowed to make use of MSA,
particularly if auto vectorisation is used when compiling a program.
The MSA context must therefore be saved & restored before & after
invoking the signal handler. Make use of the extended context structs
defined in the preceding patch to save MSA context after the sigframe
when appropriate.
[ralf@linux-mips.org: Fixed conflicts.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10796/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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The context introduced by MSA needs to be saved around signals. However,
we can't increase the size of struct sigcontext because that will change
the offset of the signal mask in struct sigframe or struct ucontext.
This patch instead places the new context immediately after the struct
sigframe for traditional signals, or similarly after struct ucontext for
RT signals. The layout of struct sigframe & struct ucontext is identical
from their sigcontext fields onwards, so the offset from the sigcontext
to the extended context will always be the same regardless of the type
of signal.
Userland will be able to search through the extended context by using
the magic values to detect which types of context are present. Any
unrecognised context can be skipped over using the size field of struct
extcontext. Once the magic value END_EXTCONTEXT_MAGIC is seen it is
known that there are no further extended context structures to examine.
This approach is somewhat similar to that taken by ARM to save VFP &
other context at the end of struct ucontext.
Userland can determine whether extended context is present by checking
for the USED_EXTCONTEXT bit in the sc_used_math field of struct
sigcontext. Whilst this could potentially change the historic semantics
of sc_used_math if further extended context which does not imply FP
context were to be introduced in the future, I have been unable to find
any userland code making use of sc_used_math at all. Using one of the
fields described as unused in struct sigcontext was considered, but the
kernel does not already write to those fields so there would be no
guarantee of the field being clear on older kernels. Other alternatives
would be to have userland check the kernel version, or to have a HWCAP
bit indicating presence of extended context. However there is a desire
to have the context & information required to decode it be self
contained such that, for example, debuggers could decode the saved
context easily.
[ralf@linux-mips.org: Fixed conflict.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: Alex Smith <alex@alex-smith.me.uk>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10795/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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The sc_used_math field of struct sigcontext & its variants has
traditionally been used as a boolean value indicating only whether or
not floating point context is saved within the sigcontext. With various
supported FP modes & the ability to switch between them this information
will no longer be enough to decode the meaning of the data stored in the
sc_fpregs fields of struct sigcontext.
To make that possible 3 bits are defined within sc_used_math:
- Bit 0 (USED_FP) represents whether FP was used, essentially
providing the boolean flag which sc_used_math as a whole provided
previously.
- Bit 1 (USED_FR1) provides the value of the Status.FR bit at the time
the FP context was saved.
- Bit 2 (USED_HYBRID_FPRS) indicates whether the FP context was saved
under the hybrid FPR scheme. Essentially, when set the odd singles
are located in bits 63:32 of the preceding even indexed sc_fpregs
element.
Any userland that tests whether the sc_used_math field is zero or
non-zero will continue to function as expected. Having said that, I
could not find any userland which uses the sc_used_math field at all.
[ralf@linux-mips.org: Fixed rejects.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10794/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Make use of the common FP sigcontext code for O32 binaries running on
MIPS64 kernels now that it is taking appropriate offsets into struct
sigcontext(32) from struct mips_abi.
[ralf@linux-mips.org: Fixed reject.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10792/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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When a task uses 32 bit floating point, the odd indexed 32b register
values are stored in bits 63:32 of the preceding even indexed 64b
FP register field in saved context. Thus there is no point in
preserving the odd indexed 64b register fields since they hold no
valid context. This patch will cause them to be skipped, as is
already done in arch/mips/kernel/signal32.c.
[ralf@linux-mips.org: Fixed reject.]
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Patchwork: https://patchwork.linux-mips.org/patch/10791/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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In preparation for sharing protected_{save,restore}_fp_context with
compat ABIs, move the FP usage checks into said functions. This will
both enable that code to be shared, and allow for extensions of it in
further patches to also be shared.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10790/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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When saving FP state to struct sigcontext, make use of the offsets
provided by struct mips_abi to obtain appropriate addresses for the
sc_fpregs & sc_fpc_csr fields of the sigcontext. This is done only for
the native struct sigcontext in this patch (ie. for O32 in CONFIG_32BIT
kernels or for N64 in CONFIG_64BIT kernels) but is done in preparation
for sharing this code with compat ABIs in further patches.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10789/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Add fields to struct mips_abi, which holds information regarding the
kernel-userland ABI regarding signals, to specify the offsets to the FP
related fields within the appropriate variant of struct sigcontext.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10788/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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The protected_{save,restore}_fp_context functions had effectively
different implementations for EVA. Simplify & unify the code somewhat
such that EVA configurations simply guarantee the FPU-not-owned path
through the standard code path.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Maciej W. Rozycki <macro@codesourcery.com>
Patchwork: https://patchwork.linux-mips.org/patch/10787/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target. This is because the
restart_block is held in the same memory allocation as the kernel stack.
Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.
Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.
It's also a decent simplification, since the restart code is more or less
identical on all architectures.
[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix:
arch/mips/kernel/signal.c: In function 'handle_signal':
arch/mips/kernel/signal.c:533:21: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
unsigned int tmp = (unsigned int)current->mm->context.vdso;
^
arch/mips/kernel/signal.c:536:9: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
vdso = (void *)tmp;
^
cc1: all warnings being treated as errors
when building a 64-bit kernel.
This is not really a supported configuration, but the cast is wrong
either way, Linux makes the assumption that sizeof(void *) equals
sizeof(unsigned long) and therefore the latter type is expected to be
used where integer operations have to be applied to pointers for some
reason.
Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8480/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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The save_fp_context & restore_fp_context pointers were being assigned
to the wrong variables if either:
- The kernel is configured for UP & runs on a system without an FPU,
since b2ead5282885 "MIPS: Move & rename
fpu_emulator_{save,restore}_context".
- The kernel is configured for EVA, since ca750649e08c "MIPS: kernel:
signal: Prevent save/restore FPU context in user memory".
This would lead to FP context being clobbered incorrectly when setting
up a sigcontext, then the garbage values being saved uselessly when
returning from the signal.
Fix by swapping the pointer assignments appropriately.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: stable@vger.kernel.org # v3.15+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8230/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Use sigsp() instead of the open coded variant.
Signed-off-by: Richard Weinberger <richard@nod.at>
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Use the more generic functions get_signal() signal_setup_done()
for signal delivery.
Signed-off-by: Richard Weinberger <richard@nod.at>
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This reverts commit eec43a224cf1 "MIPS: Save/restore MSA context around
signals" and the MSA parts of ca750649e08c "MIPS: kernel: signal:
Prevent save/restore FPU context in user memory" (the restore path of
which appears incorrect anyway...).
The reverted patch took care not to break compatibility with userland
users of struct sigcontext, but inadvertantly changed the offset of the
uc_sigmask field of struct ucontext. Thus Linux v3.15 breaks the
userland ABI. The MSA context will need to be saved via some other
opt-in mechanism, but for now revert the change to reduce the fallout.
This will have minimal impact upon use of MSA since the only supported
CPU which includes it (the P5600) is 32-bit and therefore requires that
the experimental CONFIG_MIPS_O32_FP64_SUPPORT Kconfig option be selected
before the kernel will set FR=1 for a task, a requirement for MSA use.
Thus the users of MSA are limited to known small groups of people & this
patch won't be breaking any previously working MSA-using userland
outside of experimental settings.
[ralf@linux-mips.org: Fixed rejects.]
Cc: stable@vger.kernel.org
Reported-by: Joseph S. Myers <joseph@codesourcery.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7107/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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EVA does not have FPU specific instructions for reading or writing
FPU registers from userspace memory.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
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This patch extends sigcontext in order to hold the most significant 64
bits of each vector register in addition to the MSA control & status
register. The least significant 64 bits are already saved as the scalar
FP context. This makes things a little awkward since the least & most
significant 64 bits of each vector register are not contiguous in
memory. Thus the copy_u & insert instructions are used to transfer the
values of the most significant 64 bits via GP registers.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6533/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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NUM_FPU_REGS just makes it clearer what's going on, rather than the
magic hard coded 32.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6424/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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When a task which has used the FPU at some point in its past takes a
signal the kernel would previously always require the task to take
ownership of the FPU whilst setting up or restoring from the sigcontext.
That means that if the task has not used the FPU within this timeslice
then the kernel would enable the FPU, restore the task's FP context into
FPU registers and then save them into the sigcontext. This seems
inefficient, and if the signal handler doesn't use FP then enabling the
FPU & the extra memory accesses are entirely wasted work.
This patch modifies the sigcontext setup & restore code to copy directly
between the tasks saved FP context & the sigcontext for any tasks which
have used FP in the past but are not currently the FPU owner (ie. have
not used FP in this timeslice).
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Qais Yousef <qais.yousef@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6423/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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These functions aren't directly related to the FPU emulator at all, they
simply copy between a thread's saved context & a sigcontext. Thus move
them to the appropriate signal files & rename them accordingly. This
makes it clearer that the functions don't require the FPU emulator in
any way.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Qais Yousef <qais.yousef@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6422/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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CPUs implementing MIPS32 R2 may include a 64-bit FPU, just as MIPS64 CPUs
do. In order to preserve backwards compatibility a 64-bit FPU will act
like a 32-bit FPU (by accessing doubles from the least significant 32
bits of an even-odd pair of FP registers) when the Status.FR bit is
zero, again just like a mips64 CPU. The standard O32 ABI is defined
expecting a 32-bit FPU, however recent toolchains support use of a
64-bit FPU from an O32 MIPS32 executable. When an ELF executable is
built to use a 64-bit FPU a new flag (EF_MIPS_FP64) is set in the ELF
header.
With this patch the kernel will check the EF_MIPS_FP64 flag when
executing an O32 binary, and set Status.FR accordingly. The addition
of O32 64-bit FP support lessens the opportunity for optimisation in
the FPU emulator, so a CONFIG_MIPS_O32_FP64_SUPPORT Kconfig option is
introduced to allow this support to be disabled for those that don't
require it.
Inspired by an earlier patch by Leonid Yegoshin, but implemented more
cleanly & correctly.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Paul Burton <paul.burton@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/6154/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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This enables support for CONFIG_NO_HZ_FULL.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Support vdso in microMIPS mode.
Signed-off-by: Douglas Leung <Douglas.Leung@imgtec.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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mips was the last architecture not using the generic variant.
Both native and compat variants switched to generic, which is
made unconditional now.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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we want to do that before branchpoint for arch-* to be able to
consolidate sys_rt_sigsuspend() declarations.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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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>
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The actual bug is a missing else statement - but really this should be
expressed using a switch() statement.
Found by Al Viro who writes "the funny thing is, it *does* work only
because r2 is syscall number and syscall number around 512 => return
value being ENOSYS and not one of ERESTART... so we really can't hit
the first if and emerge from it with ERESTART_RESTARTBLOCK. still
wrong to write it that way..."
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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too late to do anything there...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Too late to do anything there...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Does block_sigmask() + tracehook_signal_handler(); called when
sigframe has been successfully built. All architectures converted
to it; block_sigmask() itself is gone now (merged into this one).
I'm still not too happy with the signature, but that's a separate
story (IMO we need a structure that would contain signal number +
siginfo + k_sigaction, so that get_signal_to_deliver() would fill one,
signal_delivered(), handle_signal() and probably setup...frame() -
take one).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Only 3 out of 63 do not. Renamed the current variant to __set_current_blocked(),
added set_current_blocked() that will exclude unblockable signals, switched
open-coded instances to it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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replace boilerplate "should we use ->saved_sigmask or ->blocked?"
with calls of obvious inlined helper...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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first fruits of ..._restore_sigmask() helpers: now we can take
boilerplate "signal didn't have a handler, clear RESTORE_SIGMASK
and restore the blocked mask from ->saved_mask" into a common
helper. Open-coded instances switched...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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guts of saved_sigmask-based sigsuspend/rt_sigsuspend. Takes
kernel sigset_t *.
Open-coded instances replaced with calling it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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As described in e6fa16ab ("signal: sigprocmask() should do
retarget_shared_pending()") the modification of current->blocked is
incorrect as we need to check whether the signal we're about to block
is pending in the shared queue.
Also, use the new helper function introduced in commit 5e6292c0f28f
("signal: add block_sigmask() for adding sigmask to current->blocked")
which centralises the code for updating current->blocked after
successfully delivering a signal and reduces the amount of duplicate
code across architectures. In the past some architectures got this
code wrong, so using this helper function should stop that from
happening again.
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Patchwork: https://patchwork.linux-mips.org/patch/3363/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Disintegrate asm/system.h for MIPS.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
cc: linux-mips@linux-mips.org
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do_signal() does __put_user() which can fault, resulting in a might_sleep()
warning in down_read(&mm->mmap_sem) and a "scheduling while atomic" warning
when mmap_sem is contented. On Swarm this also results in:
WARNING: at kernel/smp.c:459 smp_call_function_many+0x148/0x398()
Modules linked in:
Call Trace:
[<ffffffff804b48a4>] dump_stack+0x1c/0x50
[<ffffffff8013dc94>] warn_slowpath_common+0x8c/0xc8
[<ffffffff8013dcfc>] warn_slowpath_null+0x2c/0x40
[<ffffffff801864a0>] smp_call_function_many+0x148/0x398
[<ffffffff80186748>] smp_call_function+0x58/0xa8
[<ffffffff80119b5c>] r4k_flush_data_cache_page+0x54/0xd8
[<ffffffff801f39bc>] handle_pte_fault+0xa9c/0xad0
[<ffffffff801f40d0>] handle_mm_fault+0x158/0x200
[<ffffffff80115548>] do_page_fault+0x218/0x3b0
[<ffffffff80102744>] ret_from_exception+0x0/0x10
[<ffffffff8010eb18>] copy_siginfo_to_user32+0x50/0x298
[<ffffffff8010edf0>] setup_rt_frame_32+0x90/0x250
[<ffffffff80106414>] do_notify_resume+0x154/0x358
[<ffffffff80102930>] work_notifysig+0xc/0x14
Fixed by enabling interrupts in do_notify_resume before delivering signals.
[ralf@linux-mips.org: Reported and original fix by tglx but I wanted to
minimize the amount of code being run with interrupts disabled so I moved
the local_irq_disable() call right into do_notify_resume. Which is saner
than doing it in entry.S.]
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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GCC-4.6 can find more unused code than previous versions could.
In the case of protected_restore_fp_context{,32}, the variable tmp is
really used. Its use is tricky in that we really care about the side
effects of the __put_user() calls. So we must mark tmp with
__maybe_unused to quiet the warning.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2035/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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o32 compat does the right thing, native and n32 compat do not...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1700/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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