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2015-02-12all arches, signal: move restart_block to struct task_structAndy Lutomirski
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>
2014-08-06mips: Use sigsp()Richard Weinberger
Use sigsp() instead of the open coded variant. Signed-off-by: Richard Weinberger <richard@nod.at>
2014-08-06mips: Use get_signal() signal_setup_done()Richard Weinberger
Use the more generic functions get_signal() signal_setup_done() for signal delivery. Signed-off-by: Richard Weinberger <richard@nod.at>
2014-06-26Revert "MIPS: Save/restore MSA context around signals"Paul Burton
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>
2014-03-26MIPS: Save/restore MSA context around signalsPaul Burton
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>
2014-03-26MIPS: Replace hardcoded 32 with NUM_FPU_REGS in ptracePaul Burton
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>
2014-03-26MIPS: Don't require FPU on sigcontext setup/restorePaul Burton
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>
2014-03-26MIPS: Move & rename fpu_emulator_{save,restore}_contextPaul Burton
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>
2014-01-13MIPS: Support for 64-bit FP with O32 binariesPaul Burton
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>
2013-11-09constify copy_siginfo_to_user{,32}()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-03-02Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linusLinus Torvalds
Pull MIPS updates from Ralf Baechle: o Add basic support for the Mediatek/Ralink Wireless SoC family. o The Qualcomm Atheros platform is extended by support for the new QCA955X SoC series as well as a bunch of patches that get the code ready for OF support. o Lantiq and BCM47XX platform have a few improvements and bug fixes. o MIPS has sent a few patches that get the kernel ready for the upcoming microMIPS support. o The rest of the series is made up of small bug fixes and cleanups that relate to various parts of the MIPS code. The biggy in there is a whitespace cleanup. After I was sent another set of whitespace cleanup patches I decided it was the time to clean the whitespace "issues" for once and and that touches many files below arch/mips/. Fix up silly conflicts, mostly due to whitespace cleanups. * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (105 commits) MIPS: Quit exporting kernel internel break codes to uapi/asm/break.h MIPS: remove broken conditional inside vpe loader code MIPS: SMTC: fix implicit declaration of set_vi_handler MIPS: early_printk: drop __init annotations MIPS: Probe for and report hardware virtualization support. MIPS: ath79: add support for the Qualcomm Atheros AP136-010 board MIPS: ath79: add USB controller registration code for the QCA955X SoCs MIPS: ath79: add PCI controller registration code for the QCA955X SoCs MIPS: ath79: add WMAC registration code for the QCA955X SoCs MIPS: ath79: register UART for the QCA955X SoCs MIPS: ath79: add QCA955X specific glue to ath79_device_reset_{set, clear} MIPS: ath79: add GPIO setup code for the QCA955X SoCs MIPS: ath79: add IRQ handling code for the QCA955X SoCs MIPS: ath79: add clock setup code for the QCA955X SoCs MIPS: ath79: add SoC detection code for the QCA955X SoCs MIPS: ath79: add early printk support for the QCA955X SoCs MIPS: ath79: fix WMAC IRQ resource assignment mips: reserve elfcorehdr mips: Make sure kernel memory is in iomem MIPS: ath79: use dynamically allocated USB platform devices ...
2013-02-03mips: switch to generic compat rt_sigaction()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03mips: sigsuspend() is essentially the same as rt_sigsuspend() hereAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03mips: switch to generic compat rt_sigqueueinfo()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03mips: switch to generic compat rt_sigpending()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03mips: switch to generic compat rt_sigprocmask()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03switch mips to generic rt_sigsuspend(), make it unconditionalAl Viro
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>
2013-02-03mips: switch to compat_sys_waitid()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-03mips: switch to generic sigaltstackAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-01MIPS: Whitespace cleanup.Ralf Baechle
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>
2012-06-01most of set_current_blocked() callers want SIGKILL/SIGSTOP removed from setAl Viro
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>
2012-05-21new helper: sigsuspend()Al Viro
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>
2012-04-27MIPS: Use set_current_blocked() and block_sigmask()Matt Fleming
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>
2012-03-28Disintegrate asm/system.h for MIPSDavid Howells
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
2011-03-14MIPS: Fix GCC-4.6 'set but not used' warning in signal*.cDavid Daney
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>
2010-04-12MIPS: Move signal trampolines off of the stack.David Daney
This is a follow on to the vdso patch. Since all processes now have signal trampolines permanently mapped, we can use those instead of putting the trampoline on the stack and invalidating the corresponding icache across all CPUs. We also get rid of a bunch of ICACHE_REFILLS_WORKAROUND_WAR code. [Ralf: GDB 7.1 which has the necessary modifications to allow backtracing over signal frames will supposedly be released tomorrow. The old signal frame format obsoleted by this patch exists in two variations, for sane processors and for those requiring ICACHE_REFILLS_WORKAROUND_WAR. So there was never a GDB which did support backtracing over signal frames on all MIPS systems. This convinved me this series should be applied and pushed upstream as soon as possible.] Signed-off-by: David Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/974/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-12-17MIPS: Cleanup signal code initializationRalf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/709/
2009-02-27MIPS: CVE-2009-0029: Enable syscall wrappers.Ralf Baechle
Thanks to David Daney helping with debugging and testing. Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: David Daney <ddaney@caviumnetworks.com>
2008-10-11MIPS: Use compat_sys_ptraceThomas Bogendoerfer
This replaces mips's sys_ptrace32 with a compat_arch_ptrace and enables the new generic definition of compat_sys_ptrace instead. Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-10-11[MIPS] Fix "no space between function name and open parenthesis" warnings.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-07-31[MIPS] remove some duplicate includesJesper Juhl
This patch removes some duplicate includes from arch/mips/ Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-06-26[MIPS] use compat_siginfo in rt_sigframe_n32Pavel Kiryukhin
Signed-off-by: Pavel Kiryukhin <vksavl@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-05-08header cleaning: don't include smp_lock.h when not usedRandy Dunlap
Remove includes of <linux/smp_lock.h> where it is not used/needed. Suggested by Al Viro. Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc, sparc64, and arm (all 59 defconfigs). Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-20[MIPS] Retry {save,restore}_fp_context if failed in atomic context.Atsushi Nemoto
The save_fp_context()/restore_fp_context() might sleep on accessing user stack and therefore might lose FPU ownership in middle of them. If these function failed due to "in_atomic" test in do_page_fault, touch the sigcontext area in non-atomic context and retry these save/restore operation. This is a replacement of a (broken) fix which was titled "Allow CpU exception in kernel partially". Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-04-20[MIPS] Disallow CpU exception in kernel again.Atsushi Nemoto
The commit 4d40bff7110e9e1a97ff8c01bdd6350e9867cc10 ("Allow CpU exception in kernel partially") was broken. The commit was to fix theoretical problem but broke usual case. Revert it for now. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-03-17[MIPS] FPU ownership management & preemption fixesAtsushi Nemoto
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-03-17[MIPS] Check FCSR for pending interrupts, alternative versionAtsushi Nemoto
Commit 6d6671066a311703bca1b91645bb1e04cc983387 is incomplete and misses non-r4k CPUs. This patch reverts the commit and fixes in other way. o Do FCSR checking in caller of restore_fp_context. o Send SIGFPE if the signal handler set any FPU exception bits. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-20[MIPS] sigset_32 has been made redundand by compat_sigset_t.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-18[MIPS] signals: Share even more code.Ralf Baechle
native and compat do_signal and handle_signal are identical and can easily be unified. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-18[MIPS] Fix sigset_t endianess swapping issues in 32-bit compat code.Atsushi Nemoto
access_ok in compat-signal.h is wrong (checking destination instead of source) and redundant (already checked before calling this function). Also sf_mask in struct sigframe32 should be compat_sigset_t type. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-13[MIPS] Fix sigset_t endianess swapping issues in 32-bit compat code.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-13[MIPS] signals: make common _BLOCKABLE macroFranck Bui-Huu
Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-13[MIPS] signal: Fix warnings in o32 compat code.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-10[MIPS] signal: do not use save_static_function() anymoreFranck Bui-Huu
This macro was used to save static registers before calling sys_sigsuspend() and sys_sigreturn(). For the sys_sigreturn() case, there's no point to save them since they have been already saved by setup_sigcontext() before calling the signal handler. For the sys_sigsuspend() case, I don't see any reasons... Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-10[MIPS] signal32: no need to save c0_status register in setup_sigcontext32()Franck Bui-Huu
All the information in the MIPS c0_status register is priviledged. Nothing that would constitute part of the thread context. The one flag one could possibly argument about might be c0_status.fr but none of the ABIs or tools or application software can make use of it. So for consistency with restore_sigcontext32(), which does not restore c0_status register, this patch remove the saving part. Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-10[MIPS] signal32: reduce {setup,restore}_sigcontext32 sizesFranck Bui-Huu
This trivial changes should decrease a lot the size of these 2 functions. Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-10[MIPS] signal: factorize debug codeFranck Bui-Huu
Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-10[MIPS] signal32: remove duplicate codeFranck Bui-Huu
There's no point for signal32.c to redefine get_sigframe(). It should use the one define in signal.c instead. The same stands for install_sigtramp(). Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-10[MIPS] signal: clean up sigframe structureFranck Bui-Huu
This patch makes 'struct sigframe' declaration avalaible for all signals code. It allows signal32 to not have its own declaration. This patch also removes all ICACHE_REFILLS_WORKAROUND_WAR tests in structure declaration and hopefully make them more readable. Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-09-27[MIPS] Avoid double signal restarting.Ralf Baechle
In entry.S resume_userspace ... jal do_notify_resume form a loop through which the kernel will iterate as long as work is pending. If we iterate through this loop more than once with no signal pending for at least one but the last iteration we will take do the syscall restarting multiple times resulting in a syscall return prior to the the syscall instruction in userspace. This may happen when debugging a multithreaded program. Debugging and original fix by Maciej; extended to other ABIs by me. Signed-off-by: Maciej W. Rozycki <macro@mips.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>