From: Chris Metcalf Date: Mon, 23 Mar 2015 18:23:58 +0000 (-0400) Subject: tile: support CONTEXT_TRACKING and thus NOHZ_FULL X-Git-Tag: firefly_0821_release~176^2~1943^2~3 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=49e4e15619cd7cd9fc275d460fae2a95c1337fcc;p=firefly-linux-kernel-4.4.55.git tile: support CONTEXT_TRACKING and thus NOHZ_FULL Add the TIF_NOHZ flag appropriately. Add call to user_exit() on entry to do_work_pending() and on entry to syscalls via do_syscall_trace_enter(), and also the top of do_syscall_trace_exit() just because it's done in x86. Add call to user_enter() at the bottom of do_work_pending() once we have no more work to do before returning to userspace. Wrap all the trap code in exception_enter() / exception_exit(). Signed-off-by: Chris Metcalf Acked-by: Frederic Weisbecker --- diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig index 7cca41842a9e..c3a31f8bb09c 100644 --- a/arch/tile/Kconfig +++ b/arch/tile/Kconfig @@ -27,6 +27,7 @@ config TILE select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE select HAVE_DEBUG_STACKOVERFLOW select ARCH_WANT_FRAME_POINTERS + select HAVE_CONTEXT_TRACKING # FIXME: investigate whether we need/want these options. # select HAVE_IOREMAP_PROT diff --git a/arch/tile/include/asm/thread_info.h b/arch/tile/include/asm/thread_info.h index 96c14c1430d8..6130a3db505b 100644 --- a/arch/tile/include/asm/thread_info.h +++ b/arch/tile/include/asm/thread_info.h @@ -126,6 +126,7 @@ extern void _cpu_idle(void); #define TIF_NOTIFY_RESUME 8 /* callback before returning to user */ #define TIF_SYSCALL_TRACEPOINT 9 /* syscall tracepoint instrumentation */ #define TIF_POLLING_NRFLAG 10 /* idle is polling for TIF_NEED_RESCHED */ +#define TIF_NOHZ 11 /* in adaptive nohz mode */ #define _TIF_SIGPENDING (1< #include #include +#include #include #include #include @@ -474,6 +475,8 @@ int do_work_pending(struct pt_regs *regs, u32 thread_info_flags) if (!user_mode(regs)) return 0; + user_exit(); + /* Enable interrupts; they are disabled again on return to caller. */ local_irq_enable(); @@ -496,11 +499,12 @@ int do_work_pending(struct pt_regs *regs, u32 thread_info_flags) tracehook_notify_resume(regs); return 1; } - if (thread_info_flags & _TIF_SINGLESTEP) { + if (thread_info_flags & _TIF_SINGLESTEP) single_step_once(regs); - return 0; - } - panic("work_pending: bad flags %#x\n", thread_info_flags); + + user_enter(); + + return 0; } unsigned long get_wchan(struct task_struct *p) diff --git a/arch/tile/kernel/ptrace.c b/arch/tile/kernel/ptrace.c index de98c6ddf136..f84eed8243da 100644 --- a/arch/tile/kernel/ptrace.c +++ b/arch/tile/kernel/ptrace.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -252,12 +253,21 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, int do_syscall_trace_enter(struct pt_regs *regs) { - if (test_thread_flag(TIF_SYSCALL_TRACE)) { + u32 work = ACCESS_ONCE(current_thread_info()->flags); + + /* + * If TIF_NOHZ is set, we are required to call user_exit() before + * doing anything that could touch RCU. + */ + if (work & _TIF_NOHZ) + user_exit(); + + if (work & _TIF_SYSCALL_TRACE) { if (tracehook_report_syscall_entry(regs)) regs->regs[TREG_SYSCALL_NR] = -1; } - if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) + if (work & _TIF_SYSCALL_TRACEPOINT) trace_sys_enter(regs, regs->regs[TREG_SYSCALL_NR]); return regs->regs[TREG_SYSCALL_NR]; @@ -267,6 +277,12 @@ void do_syscall_trace_exit(struct pt_regs *regs) { long errno; + /* + * We may come here right after calling schedule_user() + * in which case we can be in RCU user mode. + */ + user_exit(); + /* * The standard tile calling convention returns the value (or negative * errno) in r0, and zero (or positive errno) in r1. @@ -303,5 +319,7 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs) /* Handle synthetic interrupt delivered only by the simulator. */ void __kprobes do_breakpoint(struct pt_regs* regs, int fault_num) { + enum ctx_state prev_state = exception_enter(); send_sigtrap(current, regs); + exception_exit(prev_state); } diff --git a/arch/tile/kernel/single_step.c b/arch/tile/kernel/single_step.c index 862973074bf9..53f7b9def07b 100644 --- a/arch/tile/kernel/single_step.c +++ b/arch/tile/kernel/single_step.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -738,6 +739,7 @@ static DEFINE_PER_CPU(unsigned long, ss_saved_pc); void gx_singlestep_handle(struct pt_regs *regs, int fault_num) { + enum ctx_state prev_state = exception_enter(); unsigned long *ss_pc = this_cpu_ptr(&ss_saved_pc); struct thread_info *info = (void *)current_thread_info(); int is_single_step = test_ti_thread_flag(info, TIF_SINGLESTEP); @@ -754,6 +756,7 @@ void gx_singlestep_handle(struct pt_regs *regs, int fault_num) __insn_mtspr(SPR_SINGLE_STEP_CONTROL_K, control); send_sigtrap(current, regs); } + exception_exit(prev_state); } diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c index bf841ca517bb..312fc134c1cb 100644 --- a/arch/tile/kernel/traps.c +++ b/arch/tile/kernel/traps.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -253,6 +254,7 @@ static int do_bpt(struct pt_regs *regs) void __kprobes do_trap(struct pt_regs *regs, int fault_num, unsigned long reason) { + enum ctx_state prev_state = exception_enter(); siginfo_t info = { 0 }; int signo, code; unsigned long address = 0; @@ -261,7 +263,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, /* Handle breakpoints, etc. */ if (is_kernel && fault_num == INT_ILL && do_bpt(regs)) - return; + goto done; /* Re-enable interrupts, if they were previously enabled. */ if (!(regs->flags & PT_FLAGS_DISABLE_IRQ)) @@ -275,7 +277,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, const char *name; char buf[100]; if (fixup_exception(regs)) /* ILL_TRANS or UNALIGN_DATA */ - return; + goto done; if (fault_num >= 0 && fault_num < ARRAY_SIZE(int_name) && int_name[fault_num] != NULL) @@ -294,7 +296,6 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, fault_num, name, regs->pc, buf); show_regs(regs); do_exit(SIGKILL); /* FIXME: implement i386 die() */ - return; } switch (fault_num) { @@ -308,7 +309,6 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, pr_err("Unreadable instruction for INT_ILL: %#lx\n", regs->pc); do_exit(SIGKILL); - return; } if (!special_ill(instr, &signo, &code)) { signo = SIGILL; @@ -319,7 +319,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, case INT_GPV: #if CHIP_HAS_TILE_DMA() if (retry_gpv(reason)) - return; + goto done; #endif /*FALLTHROUGH*/ case INT_UDN_ACCESS: @@ -346,7 +346,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, if (!state || (void __user *)(regs->pc) != state->buffer) { single_step_once(regs); - return; + goto done; } } #endif @@ -380,7 +380,6 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, #endif default: panic("Unexpected do_trap interrupt number %d", fault_num); - return; } info.si_signo = signo; @@ -391,6 +390,9 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, if (signo != SIGTRAP) trace_unhandled_signal("trap", regs, address, signo); force_sig_info(signo, &info, current); + +done: + exception_exit(prev_state); } void kernel_double_fault(int dummy, ulong pc, ulong lr, ulong sp, ulong r52) diff --git a/arch/tile/kernel/unaligned.c b/arch/tile/kernel/unaligned.c index 7d9a83be0aca..d075f92ccee0 100644 --- a/arch/tile/kernel/unaligned.c +++ b/arch/tile/kernel/unaligned.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -1448,6 +1449,7 @@ void jit_bundle_gen(struct pt_regs *regs, tilegx_bundle_bits bundle, void do_unaligned(struct pt_regs *regs, int vecnum) { + enum ctx_state prev_state = exception_enter(); tilegx_bundle_bits __user *pc; tilegx_bundle_bits bundle; struct thread_info *info = current_thread_info(); @@ -1487,12 +1489,11 @@ void do_unaligned(struct pt_regs *regs, int vecnum) (int)unaligned_fixup, (unsigned long long)regs->ex1, (unsigned long long)regs->pc); - return; + } else { + /* Not fixable. Go panic. */ + panic("Unalign exception in Kernel. pc=%lx", + regs->pc); } - /* Not fixable. Go panic. */ - panic("Unalign exception in Kernel. pc=%lx", - regs->pc); - return; } else { /* * Try to fix the exception. If we can't, panic the @@ -1501,8 +1502,8 @@ void do_unaligned(struct pt_regs *regs, int vecnum) bundle = GX_INSN_BSWAP( *((tilegx_bundle_bits *)(regs->pc))); jit_bundle_gen(regs, bundle, align_ctl); - return; } + goto done; } /* @@ -1526,7 +1527,7 @@ void do_unaligned(struct pt_regs *regs, int vecnum) trace_unhandled_signal("unaligned fixup trap", regs, 0, SIGBUS); force_sig_info(info.si_signo, &info, current); - return; + goto done; } @@ -1543,7 +1544,7 @@ void do_unaligned(struct pt_regs *regs, int vecnum) trace_unhandled_signal("segfault in unalign fixup", regs, (unsigned long)info.si_addr, SIGSEGV); force_sig_info(info.si_signo, &info, current); - return; + goto done; } if (!info->unalign_jit_base) { @@ -1578,7 +1579,7 @@ void do_unaligned(struct pt_regs *regs, int vecnum) if (IS_ERR((void __force *)user_page)) { pr_err("Out of kernel pages trying do_mmap\n"); - return; + goto done; } /* Save the address in the thread_info struct */ @@ -1591,6 +1592,9 @@ void do_unaligned(struct pt_regs *regs, int vecnum) /* Generate unalign JIT */ jit_bundle_gen(regs, GX_INSN_BSWAP(bundle), align_ctl); + +done: + exception_exit(prev_state); } #endif /* __tilegx__ */ diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c index 0f61a73534e6..e83cc999da02 100644 --- a/arch/tile/mm/fault.c +++ b/arch/tile/mm/fault.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include @@ -702,6 +703,7 @@ void do_page_fault(struct pt_regs *regs, int fault_num, unsigned long address, unsigned long write) { int is_page_fault; + enum ctx_state prev_state = exception_enter(); #ifdef CONFIG_KPROBES /* @@ -711,7 +713,7 @@ void do_page_fault(struct pt_regs *regs, int fault_num, */ if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1, regs->faultnum, SIGSEGV) == NOTIFY_STOP) - return; + goto done; #endif #ifdef __tilegx__ @@ -750,7 +752,6 @@ void do_page_fault(struct pt_regs *regs, int fault_num, current->comm, current->pid, pc, address); show_regs(regs); do_group_exit(SIGKILL); - return; } } #else @@ -834,12 +835,15 @@ void do_page_fault(struct pt_regs *regs, int fault_num, async->is_fault = is_page_fault; async->is_write = write; async->address = address; - return; + goto done; } } #endif handle_page_fault(regs, fault_num, is_page_fault, address, write); + +done: + exception_exit(prev_state); }