user/sven/linux.git/arch/arc/kernel, branch v4.9.254

ARC: stack unwinding: don't assume non-current task is sleeping

2020-12-29T12:44:47Z

[ Upstream commit e42404fa10fd11fe72d0a0e149a321d10e577715 ] To start stack unwinding (SP, PC and BLINK) are needed. When the explicit execution context (pt_regs etc) is not available, unwinder assumes the task is sleeping (in __switch_to()) and fetches SP and BLINK from kernel mode stack. But this assumption is not true, specially in a SMP system, when top runs on 1 core, there may be active running processes on all cores. So when unwinding non courrent tasks, ensure they are NOT running. And while at it, handle the self unwinding case explicitly. This came out of investigation of a customer reported hang with rcutorture+top Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/31 Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

Revert "ARC: entry: fix potential EFA clobber when TIF_SYSCALL_TRACE"

2020-11-10T09:24:04Z

This reverts commit 00fdec98d9881bf5173af09aebd353ab3b9ac729. (but only from 5.2 and prior kernels) The original commit was a preventive fix based on code-review and was auto-picked for stable back-port (for better or worse). It was OK for v5.3+ kernels, but turned up needing an implicit change 68e5c6f073bcf70 "(ARC: entry: EV_Trap expects r10 (vs. r9) to have exception cause)" merged in v5.3 which itself was not backported. So to summarize the stable backport of this patch for v5.2 and prior kernels is busted and it won't boot. The obvious solution is backport 68e5c6f073bcf70 but that is a pain as it doesn't revert cleanly and each of affected kernels (so far v4.19, v4.14, v4.9, v4.4) needs a slightly different massaged varaint. So the easier fix is to simply revert the backport from 5.2 and prior. The issue was not a big deal as it would cause strace to sporadically not work correctly. Waldemar Brodkorb first reported this when running ARC uClibc regressions on latest stable kernels (with offending backport). Once he bisected it, the analysis was trivial, so thx to him for this. Reported-by: Waldemar Brodkorb Bisected-by: Waldemar Brodkorb Cc: stable # 5.2 and prior Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARC: stack unwinding: avoid indefinite looping

2020-11-10T09:24:04Z

commit 328d2168ca524d501fc4b133d6be076142bd305c upstream. Currently stack unwinder is a while(1) loop which relies on the dwarf unwinder to signal termination, which in turn relies on dwarf info to do so. This in theory could cause an infinite loop if the dwarf info was somehow messed up or the register contents were etc. This fix thus detects the excessive looping and breaks the loop. | Mem: 26184K used, 1009136K free, 0K shrd, 0K buff, 14416K cached | CPU: 0.0% usr 72.8% sys 0.0% nic 27.1% idle 0.0% io 0.0% irq 0.0% sirq | Load average: 4.33 2.60 1.11 2/74 139 | PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND | 133 2 root SWN 0 0.0 3 22.9 [rcu_torture_rea] | 132 2 root SWN 0 0.0 0 22.0 [rcu_torture_rea] | 131 2 root SWN 0 0.0 3 21.5 [rcu_torture_rea] | 126 2 root RW 0 0.0 2 5.4 [rcu_torture_wri] | 129 2 root SWN 0 0.0 0 0.2 [rcu_torture_fak] | 137 2 root SW 0 0.0 0 0.2 [rcu_torture_cbf] | 127 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 138 115 root R 1464 0.1 2 0.1 top | 130 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 128 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 115 1 root S 1472 0.1 1 0.0 -/bin/sh | 104 1 root S 1464 0.1 0 0.0 inetd | 1 0 root S 1456 0.1 2 0.0 init | 78 1 root S 1456 0.1 0 0.0 syslogd -O /var/log/messages | 134 2 root SW 0 0.0 2 0.0 [rcu_torture_sta] | 10 2 root IW 0 0.0 1 0.0 [rcu_preempt] | 88 2 root IW 0 0.0 1 0.0 [kworker/1:1-eve] | 66 2 root IW 0 0.0 2 0.0 [kworker/2:2-eve] | 39 2 root IW 0 0.0 2 0.0 [kworker/2:1-eve] | unwinder looping too long, aborting ! Cc: Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARC: entry: fix potential EFA clobber when TIF_SYSCALL_TRACE

2020-07-22T07:10:47Z

commit 00fdec98d9881bf5173af09aebd353ab3b9ac729 upstream. Trap handler for syscall tracing reads EFA (Exception Fault Address), in case strace wants PC of trap instruction (EFA is not part of pt_regs as of current code). However this EFA read is racy as it happens after dropping to pure kernel mode (re-enabling interrupts). A taken interrupt could context-switch, trigger a different task's trap, clobbering EFA for this execution context. Fix this by reading EFA early, before re-enabling interrupts. A slight side benefit is de-duplication of FAKE_RET_FROM_EXCPN in trap handler. The trap handler is common to both ARCompact and ARCv2 builds too. This just came out of code rework/review and no real problem was reported but is clearly a potential problem specially for strace. Cc: Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARC: Fix ICCM & DCCM runtime size checks

2020-06-11T07:22:19Z

[ Upstream commit 43900edf67d7ef3ac8909854d75b8a1fba2d570c ] As of today the ICCM and DCCM size checks are incorrectly using mismatched units (KiB checked against bytes). The CONFIG_ARC_DCCM_SZ and CONFIG_ARC_ICCM_SZ are in KiB, but the size calculated in runtime and stored in cpu->dccm.sz and cpu->iccm.sz is in bytes. Fix that. Reported-by: Paul Greco Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: perf: Accommodate big-endian CPU

2019-11-28T17:29:03Z

commit 5effc09c4907901f0e71e68e5f2e14211d9a203f upstream. 8-letter strings representing ARC perf events are stores in two 32-bit registers as ASCII characters like that: "IJMP", "IALL", "IJMPTAK" etc. And the same order of bytes in the word is used regardless CPU endianness. Which means in case of big-endian CPU core we need to swap bytes to get the same order as if it was on little-endian CPU. Otherwise we're seeing the following error message on boot: ------------------------->8---------------------- ARC perf : 8 counters (32 bits), 40 conditions, [overflow IRQ support] sysfs: cannot create duplicate filename '/devices/arc_pct/events/pmji' CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.18 #3 Stack Trace: arc_unwind_core+0xd4/0xfc dump_stack+0x64/0x80 sysfs_warn_dup+0x46/0x58 sysfs_add_file_mode_ns+0xb2/0x168 create_files+0x70/0x2a0 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at kernel/events/core.c:12144 perf_event_sysfs_init+0x70/0xa0 Failed to register pmu: arc_pct, reason -17 Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.18 #3 Stack Trace: arc_unwind_core+0xd4/0xfc dump_stack+0x64/0x80 __warn+0x9c/0xd4 warn_slowpath_fmt+0x22/0x2c perf_event_sysfs_init+0x70/0xa0 ---[ end trace a75fb9a9837bd1ec ]--- ------------------------->8---------------------- What happens here we're trying to register more than one raw perf event with the same name "PMJI". Why? Because ARC perf events are 4 to 8 letters and encoded into two 32-bit words. In this particular case we deal with 2 events: * "IJMP____" which counts all jump & branch instructions * "IJMPC___" which counts only conditional jumps & branches Those strings are split in two 32-bit words this way "IJMP" + "____" & "IJMP" + "C___" correspondingly. Now if we read them swapped due to CPU core being big-endian then we read "PMJI" + "____" & "PMJI" + "___C". And since we interpret read array of ASCII letters as a null-terminated string on big-endian CPU we end up with 2 events of the same name "PMJI". Signed-off-by: Alexey Brodkin Cc: stable@vger.kernel.org Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARC: export "abort" for modules

2019-09-21T05:14:23Z

This is a custom patch (no mainline equivalent) for stable backport only to address 0-Day kernel test infra ARC 4.x.y builds errors. The reason for this custom patch as that it is a single patch, touches only ARC, vs. atleast two 7c2c11b208be09c1, dc8635b78cd8669 which touch atleast 3 other arches (one long removed) and could potentially have a fallout. Reported-by: kbuild test robot CC: stable@vger.kernel.org # 4.4, 4.9 Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARC: hide unused function unw_hdr_alloc

2019-07-21T07:06:07Z

commit fd5de2721ea7d16e2b16c4049ac49f229551b290 upstream. As kernelci.org reports, this function is not used in vdk_hs38_defconfig: arch/arc/kernel/unwind.c:188:14: warning: 'unw_hdr_alloc' defined but not used [-Wunused-function] Fixes: bc79c9a72165 ("ARC: dw2 unwind: Reinstante unwinding out of modules") Link: https://kernelci.org/build/id/5d1cae3f59b514300340c132/logs/ Cc: stable@vger.kernel.org Signed-off-by: Arnd Bergmann Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARC: handle gcc generated __builtin_trap for older compiler

2019-07-10T07:55:44Z

commit af1be2e21203867cb958aaceed5366e2e24b88e8 upstream. ARC gcc prior to GNU 2018.03 release didn't have a target specific __builtin_trap() implementation, generating default abort() call. Implement the abort() call - emulating what newer gcc does for the same, as suggested by Arnd. Acked-by: Arnd Bergmann Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARC: u-boot args: check that magic number is correct

2019-04-20T07:07:45Z

[ Upstream commit edb64bca50cd736c6894cc6081d5263c007ce005 ] In case of devboards we really often disable bootloader and load Linux image in memory via JTAG. Even if kernel tries to verify uboot_tag and uboot_arg there is sill a chance that we treat some garbage in registers as valid u-boot arguments in JTAG case. E.g. it is enough to have '1' in r0 to treat any value in r2 as a boot command line. So check that magic number passed from u-boot is correct and drop u-boot arguments otherwise. That helps to reduce the possibility of using garbage as u-boot arguments in JTAG case. We can safely check U-boot magic value (0x0) in linux passed via r1 register as U-boot pass it from the beginning. So there is no backward-compatibility issues. Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin