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2021-12-13exit: Add and use make_task_dead.Eric W. Biederman1-4/+4
There are two big uses of do_exit. The first is it's design use to be the guts of the exit(2) system call. The second use is to terminate a task after something catastrophic has happened like a NULL pointer in kernel code. Add a function make_task_dead that is initialy exactly the same as do_exit to cover the cases where do_exit is called to handle catastrophic failure. In time this can probably be reduced to just a light wrapper around do_task_dead. For now keep it exactly the same so that there will be no behavioral differences introducing this new concept. Replace all of the uses of do_exit that use it for catastraphic task cleanup with make_task_dead to make it clear what the code is doing. As part of this rename rewind_stack_do_exit rewind_stack_and_make_dead. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-10arch: Make ARCH_STACKWALK independent of STACKTRACEPeter Zijlstra1-2/+1
Make arch_stack_walk() available for ARCH_STACKWALK architectures without it being entangled in STACKTRACE. Link: https://lore.kernel.org/lkml/20211022152104.356586621@infradead.org/ Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [Mark: rebase, drop unnecessary arm change] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Borislav Petkov <bp@alien8.de> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Link: https://lore.kernel.org/r/20211129142849.3056714-2-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-09powerpc/fadump: Fix inaccurate CPU state info in vmcore generated with panicHari Bathini2-0/+18
In panic path, fadump is triggered via a panic notifier function. Before calling panic notifier functions, smp_send_stop() gets called, which stops all CPUs except the panic'ing CPU. Commit 8389b37dffdc ("powerpc: stop_this_cpu: remove the cpu from the online map.") and again commit bab26238bbd4 ("powerpc: Offline CPU in stop_this_cpu()") started marking CPUs as offline while stopping them. So, if a kernel has either of the above commits, vmcore captured with fadump via panic path would not process register data for all CPUs except the panic'ing CPU. Sample output of crash-utility with such vmcore: # crash vmlinux vmcore ... KERNEL: vmlinux DUMPFILE: vmcore [PARTIAL DUMP] CPUS: 1 DATE: Wed Nov 10 09:56:34 EST 2021 UPTIME: 00:00:42 LOAD AVERAGE: 2.27, 0.69, 0.24 TASKS: 183 NODENAME: XXXXXXXXX RELEASE: 5.15.0+ VERSION: #974 SMP Wed Nov 10 04:18:19 CST 2021 MACHINE: ppc64le (2500 Mhz) MEMORY: 8 GB PANIC: "Kernel panic - not syncing: sysrq triggered crash" PID: 3394 COMMAND: "bash" TASK: c0000000150a5f80 [THREAD_INFO: c0000000150a5f80] CPU: 1 STATE: TASK_RUNNING (PANIC) crash> p -x __cpu_online_mask __cpu_online_mask = $1 = { bits = {0x2, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0} } crash> crash> crash> p -x __cpu_active_mask __cpu_active_mask = $2 = { bits = {0xff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0} } crash> While this has been the case since fadump was introduced, the issue was not identified for two probable reasons: - In general, the bulk of the vmcores analyzed were from crash due to exception. - The above did change since commit 8341f2f222d7 ("sysrq: Use panic() to force a crash") started using panic() instead of deferencing NULL pointer to force a kernel crash. But then commit de6e5d38417e ("powerpc: smp_send_stop do not offline stopped CPUs") stopped marking CPUs as offline till kernel commit bab26238bbd4 ("powerpc: Offline CPU in stop_this_cpu()") reverted that change. To ensure post processing register data of all other CPUs happens as intended, let panic() function take the crash friendly path (read crash_smp_send_stop()) with the help of crash_kexec_post_notifiers option. Also, as register data for all CPUs is captured by f/w, skip IPI callbacks here for fadump, to avoid any complications in finding the right backtraces. Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211207103719.91117-2-hbathini@linux.ibm.com
2021-12-09powerpc: handle kdump appropriately with crash_kexec_post_notifiers optionHari Bathini1-0/+30
Kdump can be triggered after panic_notifers since commit f06e5153f4ae2 ("kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers") introduced crash_kexec_post_notifiers option. But using this option would mean smp_send_stop(), that marks all other CPUs as offline, gets called before kdump is triggered. As a result, kdump routines fail to save other CPUs' registers. To fix this, kdump friendly crash_smp_send_stop() function was introduced with kernel commit 0ee59413c967 ("x86/panic: replace smp_send_stop() with kdump friendly version in panic path"). Override this kdump friendly weak function to handle crash_kexec_post_notifiers option appropriately on powerpc. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> [Fixed signature of crash_stop_this_cpu() - reported by lkp@intel.com] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211207103719.91117-1-hbathini@linux.ibm.com
2021-12-09powerpc/inst: Define ppc_inst_t as u32 on PPC32Christophe Leroy1-6/+2
Unlike PPC64 ABI, PPC32 uses the stack to pass a parameter defined as a struct, even when the struct has a single simple element. To avoid that, define ppc_inst_t as u32 on PPC32. Keep it as 'struct ppc_inst' when __CHECKER__ is defined so that sparse can perform type checking. Also revert commit 511eea5e2ccd ("powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32") as now the instruction to be emulated is passed as a register to emulate_step(). Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/c6d0c46f598f76ad0b0a88bc0d84773bd921b17c.1638208156.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/inst: Define ppc_inst_tChristophe Leroy11-42/+42
In order to stop using 'struct ppc_inst' on PPC32, define a ppc_inst_t typedef. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/fe5baa2c66fea9db05a8b300b3e8d2880a42596c.1638208156.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/kuap: Wire-up KUAP on 85xx in 32 bits mode.Christophe Leroy1-0/+12
This adds KUAP support to 85xx in 32 bits mode. This is done by reading the content of SPRN_MAS1 and checking the TID at the time user pgtable is loaded. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/f8696f8980ca1532ada3a2f0e0a03e756269c7fe.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/kuap: Wire-up KUAP on 40xChristophe Leroy1-0/+8
This adds KUAP support to 40x. This is done by checking the content of SPRN_PID at the time user pgtable is loaded. 40x doesn't have KUEP, but KUAP implies KUEP because when the PID doesn't match the page's PID, the page cannot be read nor executed. So KUEP is now automatically selected when KUAP is selected and disabled when KUAP is disabled. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/aaefa91897ddc42ac11019dc0e1d1a525bd08e90.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/kuap: Wire-up KUAP on 44xChristophe Leroy1-0/+16
This adds KUAP support to 44x. This is done by checking the content of SPRN_PID at the time it is read and written into SPRN_MMUCR. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/7d6c3f1978a26feada74b084f651e8cf1e3b3a47.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc: Add KUAP support for BOOKE and 40xChristophe Leroy1-0/+3
On booke/40x we don't have segments like book3s/32. On booke/40x we don't have access protection groups like 8xx. Use the PID register to provide user access protection. Kernel address space can be accessed with any PID. User address space has to be accessed with the PID of the user. User PID is always not null. Everytime the kernel is entered, set PID register to 0 and restore PID register when returning to user. Everytime kernel needs to access user data, PID is restored for the access. In TLB miss handlers, check the PID and bail out to data storage exception when PID is 0 and accessed address is in user space. Note that also forbids execution of user text by kernel except when user access is unlocked. But this shouldn't be a problem as the kernel is not supposed to ever run user text. This patch prepares the infrastructure but the real activation of KUAP is done by following patches for each processor type one by one. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/5d65576a8e31e9480415785a180c92dd4e72306d.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/kuap: Prepare for supporting KUAP on BOOK3E/64Christophe Leroy1-3/+3
Also call kuap_lock() and kuap_save_and_lock() from interrupt functions with CONFIG_PPC64. For book3s/64 we keep them empty as it is done in assembly. Also do the locked assert when switching task unless it is book3s/64. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1cbf94e26e6d6e2e028fd687588a7e6622d454a6.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/config: Add CONFIG_BOOKE_OR_40xChristophe Leroy7-8/+8
We have many functionnalities common to 40x and BOOKE, it leads to many places with #if defined(CONFIG_BOOKE) || defined(CONFIG_40x). We are going to add a few more with KUAP for booke/40x, so create a new symbol which is defined when either BOOKE or 40x is defined. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/9a3dbd60924cb25c9f944d3d8205ac5a0d15e229.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/kuap: Add kuap_lock()Christophe Leroy1-0/+2
Add kuap_lock() and call it when entering interrupts from user. It is called kuap_lock() as it is similar to kuap_save_and_lock() without the save. However book3s/32 already have a kuap_lock(). Rename it kuap_lock_addr(). Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/4437e2deb9f6f549f7089d45e9c6f96a7e77905a.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/32s: Save content of sr0 to avoid 'mfsr'Christophe Leroy2-5/+4
Calling 'mfsr' to get the content of segment registers is heavy, in addition it requires clearing of the 'reserved' bits. In order to avoid this operation, save it in mm context and in thread struct. The saved sr0 is the one used by kernel, this means that on locking entry it can be used as is. For unlocking, the only thing to do is to clear SR_NX. This improves null_syscall selftest by 12 cycles, ie 4%. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/b02baf2ed8f09bad910dfaeeb7353b2ae6830525.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/32s: Do kuep_lock() and kuep_unlock() in assemblyChristophe Leroy4-3/+41
When interrupt and syscall entries where converted to C, KUEP locking and unlocking was also converted. It improved performance by unrolling the loop, and allowed easily implementing boot time deactivation of KUEP. However, null_syscall selftest shows that KUEP is still heavy (361 cycles with KUEP, 212 cycles without). A way to improve more is to group 'mtsr's together, instead of repeating 'addi' + 'mtsr' several times. In order to do that, more registers need to be available. In C, GCC will always be able to provide the requested number of registers, but at the cost of saving some data on the stack, which is counter performant here. So let's do it in assembly, when we have full control of which register can be used. It also has the advantage of locking earlier and unlocking later and it helps GCC generating less tricky code. The only drawback is to make boot time deactivation less straight forward and require 'hand' instruction patching. Group 'mtsr's by 4. With this change, null_syscall selftest reports 336 cycles. Without the change it was 361 cycles, that's a 7% reduction. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/115cb279e9b9948dfd93a065e047081c59e3a2a6.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/book3e: Activate KUEP at all timeChristophe Leroy1-0/+1
On book3e, - When using 64 bits PTE: User pages don't have the SX bit defined so KUEP is always active. - When using 32 bits PTE: Implement KUEP by clearing SX bit during TLB miss for user pages. The impact is minimal and worth neither boot time nor build time selection. Activate it at all time. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/e376b114283fb94504e2aa2de846780063252cde.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/44x: Activate KUEP at all timeChristophe Leroy1-8/+2
On 44x, KUEP is implemented by clearing SX bit during TLB miss for user pages. The impact is minimal and not worth neither boot time nor build time selection. Activate it at all time. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/2414d662558e7fb27d1ed41c8e47c591d576acac.1634627931.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/40x: Map 32Mbytes of memory at startupChristophe Leroy1-1/+8
As reported by Carlo, 16Mbytes is not enough with modern kernels that tend to be a bit big, so map another 16M page at boot. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/89b5f974a7fa5011206682cd092e2c905530ff46.1632755552.git.christophe.leroy@csgroup.eu
2021-12-09powerpc/64s: Move hash MMU support code under CONFIG_PPC_64S_HASH_MMUNicholas Piggin9-25/+44
Compiling out hash support code when CONFIG_PPC_64S_HASH_MMU=n saves 128kB kernel image size (90kB text) on powernv_defconfig minus KVM, 350kB on pseries_defconfig minus KVM, 40kB on a tiny config. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Fixup defined(ARCH_HAS_MEMREMAP_COMPAT_ALIGN), which needs CONFIG. Fix radix_enabled() use in setup_initial_memory_limit(). Add some stubs to reduce number of ifdefs.] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211201144153.2456614-18-npiggin@gmail.com
2021-12-09powerpc/64s: Make hash MMU support configurableNicholas Piggin1-4/+10
This adds Kconfig selection which allows 64s hash MMU support to be disabled. It can be disabled if radix support is enabled, the minimum supported CPU type is POWER9 (or higher), and KVM is not selected. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211201144153.2456614-17-npiggin@gmail.com
2021-12-02powerpc/64: pcpu setup avoid reading mmu_linear_psize on 64e or radixNicholas Piggin1-6/+15
Radix never sets mmu_linear_psize so it's always 4K, which causes pcpu atom_size to always be PAGE_SIZE. 64e sets it to 1GB always. Make paths for these platforms to be explicit about what value they set atom_size to. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211201144153.2456614-12-npiggin@gmail.com
2021-12-02powerpc/64s: Make flush_and_reload_slb a no-op when radix is enabledNicholas Piggin1-3/+3
The radix test can exclude slb_flush_all_realmode() from being called because flush_and_reload_slb() is only expected to flush ERAT when called by flush_erat(), which is only on pre-ISA v3.0 CPUs that do not support radix. This helps the later change to make hash support configurable to not introduce runtime changes to radix mode behaviour. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211201144153.2456614-9-npiggin@gmail.com
2021-12-02powerpc/64s: Move and rename do_bad_slb_fault as it is not hash specificNicholas Piggin1-2/+2
slb.c is hash-specific SLB management, but do_bad_slb_fault deals with segment interrupts that occur with radix MMU as well. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211201144153.2456614-5-npiggin@gmail.com
2021-12-02powerpc/signal32: Use struct_group() to zero spe regsKees Cook1-5/+9
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields. Add a struct_group() for the spe registers so that memset() can correctly reason about the size: In function 'fortify_memset_chk', inlined from 'restore_user_regs.part.0' at arch/powerpc/kernel/signal_32.c:539:3: >> include/linux/fortify-string.h:195:4: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 195 | __write_overflow_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211118203604.1288379-1-keescook@chromium.org
2021-12-01powerpc: Snapshot thread flagsMark Rutland2-9/+7
Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not. Convert them all to the new flag accessor helpers. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Paul E. McKenney <paulmck@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Link: https://lore.kernel.org/r/20211129130653.2037928-11-mark.rutland@arm.com
2021-12-01powerpc: Avoid discarding flags in system_call_exception()Mark Rutland1-1/+1
Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Thus, when setting flags we must use an atomic operation rather than a plain read-modify-write sequence, as a plain read-modify-write may discard flags which are concurrently set by a remote thread, e.g. // task A // task B tmp = A->thread_info.flags; set_tsk_thread_flag(A, NEWFLAG_B); tmp |= NEWFLAG_A; A->thread_info.flags = tmp; arch/powerpc/kernel/interrupt.c's system_call_exception() sets _TIF_RESTOREALL in the thread info flags with a read-modify-write, which may result in other flags being discarded. Elsewhere in the file it uses clear_bits() to atomically remove flag bits, so use set_bits() here for consistency with those. There may be reasons (e.g. instrumentation) that prevent the use of set_thread_flag() and clear_thread_flag() here, which would otherwise be preferable. Fixes: ae7aaecc3f2f78b7 ("powerpc/64s: system call rfscv workaround for TM bugs") Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Eirik Fuller <efuller@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Link: https://lore.kernel.org/r/20211129130653.2037928-10-mark.rutland@arm.com
2021-11-30powerpc/modules: Don't WARN on first module allocation attemptChristophe Leroy1-5/+6
module_alloc() first tries to allocate module text within 24 bits direct jump from kernel text, and tries a wider allocation if first one fails. When first allocation fails the following is observed in kernel logs: vmap allocation for size 2400256 failed: use vmalloc=<size> to increase size systemd-udevd: vmalloc error: size 2395133, vm_struct allocation failed, mode:0xcc0(GFP_KERNEL), nodemask=(null) CPU: 0 PID: 127 Comm: systemd-udevd Tainted: G W 5.15.5-gentoo-PowerMacG4 #9 Call Trace: [e2a53a50] [c0ba0048] dump_stack_lvl+0x80/0xb0 (unreliable) [e2a53a70] [c0540128] warn_alloc+0x11c/0x2b4 [e2a53b50] [c0531be8] __vmalloc_node_range+0xd8/0x64c [e2a53c10] [c00338c0] module_alloc+0xa0/0xac [e2a53c40] [c027a368] load_module+0x2ae0/0x8148 [e2a53e30] [c027fc78] sys_finit_module+0xfc/0x130 [e2a53f30] [c0035098] ret_from_syscall+0x0/0x28 ... Add __GFP_NOWARN flag to first allocation so that no warning appears when it fails. Reported-by: Erhard Furtner <erhard_f@mailbox.org> Fixes: 2ec13df16704 ("powerpc/modules: Load modules closer to kernel text") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/93c9b84d6ec76aaf7b4f03468e22433a6d308674.1638267035.git.christophe.leroy@csgroup.eu
2021-11-29powerpc: flexible GPR range save/restore macrosNicholas Piggin9-75/+42
Introduce macros that operate on a (start, end) range of GPRs, which reduces lines of code and need to do mental arithmetic while reading the code. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211022061322.2671178-1-npiggin@gmail.com
2021-11-29powerpc/watchdog: help remote CPUs to flush NMI printk outputNicholas Piggin1-6/+31
The printk layer at the moment does not seem to have a good way to force flush printk messages that are created in NMI context, except in the panic path. NMI-context printk messages normally get to the console with irq_work, but that won't help if the CPU is stuck with irqs disabled, as can be the case for hard lockup watchdog messages. The watchdog currently flushes the printk buffers after detecting a lockup on remote CPUs, but they may not have processed their NMI IPI yet by that stage, or they may have self-detected a lockup in which case they won't go via this NMI IPI path. Improve the situation by having NMI-context mark a flag if it called printk, and have watchdog timer interrupts check if that flag was set and try to flush if it was. Latency is not a big problem because we were already stuck for a while, just need to try to make sure the messages eventually make it out. Depends-on: 5d5e4522a7f4 ("printk: restore flushing of NMI buffers on remote CPUs after NMI backtraces") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211119113146.752759-6-npiggin@gmail.com
2021-11-29powerpc: Don't bother about .data..Lubsan sectionsChristophe Leroy1-8/+0
Since commit 9a427556fb8e ("vmlinux.lds.h: catch compound literals into data and BSS") .data..Lubsan sections are taken into account in DATA_MAIN which is included in DATA_DATA macro. No need to take care of them anymore in powerpc vmlinux.lds.S Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/3eb14570612eef17e01bb67f14a4450136001794.1637840601.git.christophe.leroy@csgroup.eu
2021-11-29powerpc/ftrace: Activate HAVE_DYNAMIC_FTRACE_WITH_REGS on PPC32Christophe Leroy3-10/+123
Unlike PPC64, PPC32 doesn't require any special compiler option to get _mcount() call not clobbering registers. Provide ftrace_regs_caller() and ftrace_regs_call() and activate HAVE_DYNAMIC_FTRACE_WITH_REGS. That's heavily copied from ftrace_64_mprofile.S For the time being leave livepatching aside, it will come with following patch. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1862dc7719855cc2a4eec80920d94c955877557e.1635423081.git.christophe.leroy@csgroup.eu
2021-11-29powerpc/ftrace: Add module_trampoline_target() for PPC32Christophe Leroy2-33/+29
module_trampoline_target() is used by __ftrace_modify_call(). Implement it for PPC32 so that CONFIG_DYNAMIC_FTRACE_WITH_REGS can be activated on PPC32 as well. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/42345f464fb465f0fc76f3090e250be8fc1729f0.1635423081.git.christophe.leroy@csgroup.eu
2021-11-29powerpc/ftrace: No need to read LR from stack in _mcount()Christophe Leroy1-5/+4
All functions calling _mcount do it exactly the same way, with the following sequence of instructions: c07de788: 7c 08 02 a6 mflr r0 c07de78c: 90 01 00 04 stw r0,4(r1) c07de790: 4b 84 13 65 bl c001faf4 <_mcount> Allthough LR is pushed on stack, it is still in r0 while entering _mcount(). Function arguments are in r3-r10, so r11 and r12 are still available at that point. Do like PPC64 and use r12 to move LR into CTR, so that r0 is preserved and doesn't need to be restored from the stack. While at it, bring back the EXPORT_SYMBOL at the end of _mcount. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/24a3ba7db388537c44a038026f926d885372e6d3.1635423081.git.christophe.leroy@csgroup.eu
2021-11-29powerpc: Mark probe_machine() __init and staticMichael Ellerman1-1/+1
Prior to commit b1923caa6e64 ("powerpc: Merge 32-bit and 64-bit setup_arch()") probe_machine() was called from setup_32/64.c and lived in setup-common.c. But now it's only called from setup-common.c so it can be static and __init, and we don't need the declaration in machdep.h either. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211124093254.1054750-6-mpe@ellerman.id.au
2021-11-29powerpc/smp: Move setup_profiling_timer() under CONFIG_PROFILINGMichael Ellerman1-0/+2
setup_profiling_timer() is only needed when CONFIG_PROFILING is enabled. Fixes the following W=1 warning when CONFIG_PROFILING=n: linux/arch/powerpc/kernel/smp.c:1638:5: error: no previous prototype for ‘setup_profiling_timer’ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211124093254.1054750-5-mpe@ellerman.id.au
2021-11-27Merge tag 'powerpc-5.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linuxLinus Torvalds1-3/+3
Pull powerpc fixes from Michael Ellerman: "Fix KVM using a Power9 instruction on earlier CPUs, which could lead to the host SLB being incorrectly invalidated and a subsequent host crash. Fix kernel hardlockup on vmap stack overflow on 32-bit. Thanks to Christophe Leroy, Nicholas Piggin, and Fabiano Rosas" * tag 'powerpc-5.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/32: Fix hardlockup on vmap stack overflow KVM: PPC: Book3S HV: Prevent POWER7/8 TLB flush flushing SLB
2021-11-25Merge tag 'asm-generic-5.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-genericLinus Torvalds1-0/+1
Pull asm-generic syscall table update from Arnd Bergmann: "André Almeida sends an update for the newly added futex_waitv syscall that was initially only added to a few architectures. Some additional ones have since made it through architecture maintainer trees, this finishes the remaining ones" * tag 'asm-generic-5.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: futex: Wireup futex_waitv syscall
2021-11-25futex: Wireup futex_waitv syscallAndré Almeida1-0/+1
Wireup futex_waitv syscall for all remaining archs. Signed-off-by: André Almeida <andrealmeid@collabora.com> Acked-by: Max Filippov <jcmvbkbc@gmail.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2021-11-25powerpc/watchdog: Fix wd_smp_last_reset_tb reportingNicholas Piggin1-4/+4
wd_smp_last_reset_tb now gets reset by watchdog_smp_panic() as part of marking CPUs stuck and removing them from the pending mask before it begins any printing. This causes last reset times reported to be off. Fix this by reading it into a local variable before it gets reset. Fixes: 76521c4b0291 ("powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211125103346.1188958-1-npiggin@gmail.com
2021-11-25powerpc/watchdog: read TB close to where it is usedNicholas Piggin1-12/+14
When taking watchdog actions, printing messages, comparing and re-setting wd_smp_last_reset_tb, etc., read TB close to the point of use and under wd_smp_lock or printing lock (if applicable). This should keep timebase mostly monotonic with kernel log messages, and could prevent (in theory) a laggy CPU updating wd_smp_last_reset_tb to something a long way in the past, and causing other CPUs to appear to be stuck. These additional TB reads are all slowpath (lockup has been detected), so performance does not matter. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211110025056.2084347-5-npiggin@gmail.com
2021-11-25powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipiNicholas Piggin1-19/+74
There is a deadlock with the console_owner lock and the wd_smp_lock: CPU x takes the console_owner lock CPU y takes a watchdog timer interrupt and takes __wd_smp_lock CPU x takes a soft-NMI interrupt, detects deadlock, spins on __wd_smp_lock CPU y detects deadlock, tries to print something and spins on console_owner -> deadlock Change the watchdog locking scheme so wd_smp_lock protects the watchdog internal data, but "reporting" (printing, issuing NMI IPIs, taking any action outside of watchdog) uses a non-waiting exclusion. If a CPU detects a problem but can not take the reporting lock, it just returns because something else is already reporting. It will try again at some point. Typically hard lockup watchdog report usefulness is not impacted due to failure to spewing a large enough amount of data in as short a time as possible, but by messages getting garbled. Laurent debugged this and found the deadlock, and this patch is based on his general approach to avoid expensive operations while holding the lock. With the addition of the reporting exclusion. Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> [np: rework to add reporting exclusion update changelog] Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211110025056.2084347-4-npiggin@gmail.com
2021-11-25powerpc/watchdog: tighten non-atomic read-modify-write accessNicholas Piggin1-10/+26
Most updates to wd_smp_cpus_pending are under lock except the watchdog interrupt bit clear. This can race with non-atomic RMW updates to the mask under lock, which can happen in two instances: Firstly, if another CPU detects this one is stuck, removes it from the mask, mask becomes empty and is re-filled with non-atomic stores. This is okay because it would re-fill the mask with this CPU's bit clear anyway (because this CPU is now stuck), so it doesn't matter that the bit clear update got "lost". Add a comment for this. Secondly, if another CPU detects a different CPU is stuck and removes it from the pending mask with a non-atomic store to bytes which also include the bit of this CPU. This case can result in the bit clear being lost and the end result being the bit is set. This should be so rare it hardly matters, but to make things simpler to reason about just avoid the non-atomic access for that case. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211110025056.2084347-3-npiggin@gmail.com
2021-11-25powerpc/watchdog: Fix missed watchdog reset due to memory ordering raceNicholas Piggin1-1/+40
It is possible for all CPUs to miss the pending cpumask becoming clear, and then nobody resetting it, which will cause the lockup detector to stop working. It will eventually expire, but watchdog_smp_panic will avoid doing anything if the pending mask is clear and it will never be reset. Order the cpumask clear vs the subsequent test to close this race. Add an extra check for an empty pending mask when the watchdog fires and finds its bit still clear, to try to catch any other possible races or bugs here and keep the watchdog working. The extra test in arch_touch_nmi_watchdog is required to prevent the new warning from firing off. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Debugged-by: Laurent Dufour <ldufour@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211110025056.2084347-2-npiggin@gmail.com
2021-11-25powerpc/prom_init: Fix improper check of prom_getprop()Peiwei Hu1-1/+1
prom_getprop() can return PROM_ERROR. Binary operator can not identify it. Fixes: 94d2dde738a5 ("[POWERPC] Efika: prune fixups and make them more carefull") Signed-off-by: Peiwei Hu <jlu.hpw@foxmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/tencent_BA28CC6897B7C95A92EB8C580B5D18589105@qq.com
2021-11-25powerpc/rtas: rtas_busy_delay_time() kernel-docNathan Lynch1-2/+19
Provide API documentation for rtas_busy_delay_time(), explaining why we return the same value for 9900 and -2. Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211117060259.957178-3-nathanl@linux.ibm.com
2021-11-25powerpc/rtas: rtas_busy_delay() improvementsNathan Lynch1-7/+67
Generally RTAS cannot block, and in PAPR it is required to return control to the OS within a few tens of microseconds. In order to support operations which may take longer to complete, many RTAS primitives can return intermediate -2 ("busy") or 990x ("extended delay") values, which indicate that the OS should reattempt the same call with the same arguments at some point in the future. Current versions of PAPR are less than clear about this, but the intended meanings of these values in more detail are: RTAS_BUSY (-2): RTAS has suspended a potentially long-running operation in order to meet its latency obligation and give the OS the opportunity to perform other work. RTAS can resume making progress as soon as the OS reattempts the call. RTAS_EXTENDED_DELAY_{MIN...MAX} (9900-9905): RTAS must wait for an external event to occur or for internal contention to resolve before it can complete the requested operation. The value encodes a non-binding hint as to roughly how long the OS should wait before calling again, but the OS is allowed to reattempt the call sooner or even immediately. Linux of course must take its own CPU scheduling obligations into account when handling these statuses; e.g. a task which receives an RTAS_BUSY status should check whether to reschedule before it attempts the RTAS call again to avoid starving other tasks. rtas_busy_delay() is a helper function that "consumes" a busy or extended delay status. Common usage: int rc; do { rc = rtas_call(rtas_token("some-function"), ...); } while (rtas_busy_delay(rc)); /* convert rc to Linux error value, etc */ If rc is a busy or extended delay status, the caller can rely on rtas_busy_delay() to perform an appropriate sleep or reschedule and return nonzero. Other statuses are handled normally by the caller. The current implementation of rtas_busy_delay() both oversleeps and overuses the CPU: * It performs msleep() for all 990x and even when no delay is suggested (-2), but this is understood to actually sleep for two jiffies minimum in practice (20ms with HZ=100). 9900 (1ms) and 9901 (10ms) appear to be the most common extended delay statuses, and the oversleeping measurably lengthens DLPAR operations, which perform many RTAS calls. * It does not sleep on 990x unless need_resched() is true, causing code like the loop above to needlessly retry, wasting CPU time. Alter the logic to align better with the intended meanings: * When passed RTAS_BUSY, perform cond_resched() and return without sleeping. The caller should reattempt immediately * Always sleep when passed an extended delay status, using usleep_range() for precise shorter sleeps. Limit the sleep time to one second even though there are higher architected values. Change rtas_busy_delay()'s return type to bool to better reflect its usage, and add kernel-doc. rtas_busy_delay_time() is unchanged, even though it "incorrectly" returns 1 for RTAS_BUSY. There are users of that API with open-coded delay loops in sensitive contexts that will have to be taken on an individual basis. Brief results for addition and removal of 5GB memory on a small P9 PowerVM partition follow. Load was generated with stress-ng --cpu N. For add, elapsed time is greatly reduced without significant change in the number of RTAS calls or time spent on CPU. For remove, elapsed time is modestly reduced, with significant reductions in RTAS calls and time spent on CPU. With no competing workload (- before, + after): Performance counter stats for 'bash -c echo "memory add count 20" > /sys/kernel/dlpar' (10 runs): - 1,935 probe:rtas_call # 0.003 M/sec ( +- 0.22% ) - 609.99 msec task-clock # 0.183 CPUs utilized ( +- 0.19% ) + 1,956 probe:rtas_call # 0.003 M/sec ( +- 0.17% ) + 618.56 msec task-clock # 0.278 CPUs utilized ( +- 0.11% ) - 3.3322 +- 0.0670 seconds time elapsed ( +- 2.01% ) + 2.2222 +- 0.0416 seconds time elapsed ( +- 1.87% ) Performance counter stats for 'bash -c echo "memory remove count 20" > /sys/kernel/dlpar' (10 runs): - 6,224 probe:rtas_call # 0.008 M/sec ( +- 2.57% ) - 750.36 msec task-clock # 0.190 CPUs utilized ( +- 2.01% ) + 843 probe:rtas_call # 0.003 M/sec ( +- 0.12% ) + 250.66 msec task-clock # 0.068 CPUs utilized ( +- 0.17% ) - 3.9394 +- 0.0890 seconds time elapsed ( +- 2.26% ) + 3.678 +- 0.113 seconds time elapsed ( +- 3.07% ) With all CPUs 100% busy (- before, + after): Performance counter stats for 'bash -c echo "memory add count 20" > /sys/kernel/dlpar' (10 runs): - 2,979 probe:rtas_call # 0.003 M/sec ( +- 0.12% ) - 1,096.62 msec task-clock # 0.105 CPUs utilized ( +- 0.10% ) + 2,981 probe:rtas_call # 0.003 M/sec ( +- 0.22% ) + 1,095.26 msec task-clock # 0.154 CPUs utilized ( +- 0.21% ) - 10.476 +- 0.104 seconds time elapsed ( +- 1.00% ) + 7.1124 +- 0.0865 seconds time elapsed ( +- 1.22% ) Performance counter stats for 'bash -c echo "memory remove count 20" > /sys/kernel/dlpar' (10 runs): - 2,702 probe:rtas_call # 0.004 M/sec ( +- 4.00% ) - 722.71 msec task-clock # 0.067 CPUs utilized ( +- 2.41% ) + 1,246 probe:rtas_call # 0.003 M/sec ( +- 0.25% ) + 487.73 msec task-clock # 0.049 CPUs utilized ( +- 0.20% ) - 10.829 +- 0.163 seconds time elapsed ( +- 1.51% ) + 9.9887 +- 0.0866 seconds time elapsed ( +- 0.87% ) Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211117060259.957178-2-nathanl@linux.ibm.com
2021-11-25powerpc/rtas: kernel-doc fixesNathan Lynch1-4/+5
Fix the following issues reported by kernel-doc: $ scripts/kernel-doc -v -none arch/powerpc/kernel/rtas.c arch/powerpc/kernel/rtas.c:810: info: Scanning doc for function rtas_activate_firmware arch/powerpc/kernel/rtas.c:818: warning: contents before sections arch/powerpc/kernel/rtas.c:841: info: Scanning doc for function rtas_call_reentrant arch/powerpc/kernel/rtas.c:893: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst * Find a specific pseries error log in an RTAS extended event log. Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211116215806.928235-1-nathanl@linux.ibm.com
2021-11-25powerpc/eeh: Use a goto for recovery failuresOliver O'Halloran1-48/+45
The EEH recovery logic in eeh_handle_normal_event() has some pretty strange flow control. If we remove all the actual recovery logic we're left with the following skeleton: if (result != PCI_ERS_RESULT_DISCONNECT) { ... } if (result != PCI_ERS_RESULT_DISCONNECT) { ... } if (result == PCI_ERS_RESULT_NONE) { ... } if (result == PCI_ERS_RESULT_CAN_RECOVER) { ... } if (result == PCI_ERS_RESULT_CAN_RECOVER) { ... } if (result == PCI_ERS_RESULT_NEED_RESET) { ... } if ((result == PCI_ERS_RESULT_RECOVERED) || (result == PCI_ERS_RESULT_NONE)) { ... goto out; } /* * unsuccessful recovery / PCI_ERS_RESULT_DISCONECTED * handling is here. */ ... out: ... Most of the "if () { ... }" blocks above change "result" to PCI_ERS_RESULT_DISCONNECTED if an error occurs in that recovery step. This makes the control flow a bit confusing since it breaks the early-exit pattern that is generally used in Linux. In any case we end up handling the error in the final else block so why not just jump there directly? Doing so also allows us to de-indent a bunch of code. No functional changes. [dja: rebase on top of linux-next + my preceeding refactor, move clearing the EEH_DEV_NO_HANDLER bit above the first goto so that it is always clear in the error handler code as it was before.] Signed-off-by: Oliver O'Halloran <oohall@gmail.com> Signed-off-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211015070628.1331635-2-dja@axtens.net
2021-11-25powerpc/eeh: Small refactor of eeh_handle_normal_event()Daniel Axtens1-34/+35
The control flow of eeh_handle_normal_event() is a bit tricky. Break out one of the error handling paths - rather than be in an else block, we'll make it part of the regular body of the function and put a 'goto out;' in the true limb of the if. Signed-off-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211015070628.1331635-1-dja@axtens.net
2021-11-25powerpc/btext: add missing of_node_putJulia Lawall1-1/+3
for_each_node_by_type performs an of_node_get on each iteration, so a break out of the loop requires an of_node_put. A simplified version of the semantic patch that fixes this problem is as follows (http://coccinelle.lip6.fr): // <smpl> @@ local idexpression n; expression e; @@ for_each_node_by_type(n,...) { ... ( of_node_put(n); | e = n | + of_node_put(n); ? break; ) ... } ... when != n // </smpl> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1448051604-25256-6-git-send-email-Julia.Lawall@lip6.fr
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