From 1fcbe027b5d29ec9cd0eeb753c14fb366ae852ac Mon Sep 17 00:00:00 2001 From: Chris Metcalf Date: Fri, 13 Aug 2010 08:40:57 -0400 Subject: arch/tile: support backtracing on TILE-Gx This functionality was stubbed out until recently. Now we support our normal backtracing API on TILE-Gx as well as on TILE64/TILEPro. This change includes a tweak to the instruction encoding caused by adding addxli for compat mode. Signed-off-by: Chris Metcalf --- arch/tile/kernel/stack.c | 8 -------- 1 file changed, 8 deletions(-) (limited to 'arch/tile/kernel/stack.c') diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c index b6268d3ae86..38a68b0b458 100644 --- a/arch/tile/kernel/stack.c +++ b/arch/tile/kernel/stack.c @@ -108,7 +108,6 @@ static bool read_memory_func(void *result, VirtualAddress address, /* Return a pt_regs pointer for a valid fault handler frame */ static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt) { -#ifndef __tilegx__ const char *fault = NULL; /* happy compiler */ char fault_buf[64]; VirtualAddress sp = kbt->it.sp; @@ -146,7 +145,6 @@ static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt) } if (!kbt->profile || (INT_MASK(p->faultnum) & QUEUED_INTERRUPTS) == 0) return p; -#endif return NULL; } @@ -351,12 +349,6 @@ void tile_show_stack(struct KBacktraceIterator *kbt, int headers) kbt->task->pid, kbt->task->tgid, kbt->task->comm, smp_processor_id(), get_cycles()); } -#ifdef __tilegx__ - if (kbt->is_current) { - __insn_mtspr(SPR_SIM_CONTROL, - SIM_DUMP_SPR_ARG(SIM_DUMP_BACKTRACE)); - } -#endif kbt->verbose = 1; i = 0; for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) { -- cgit v1.2.3-70-g09d2 From 74fca9da097b74117ae2cef9e5f0d9b0e28ccbb7 Mon Sep 17 00:00:00 2001 From: Chris Metcalf Date: Wed, 15 Sep 2010 11:16:08 -0400 Subject: arch/tile: Change struct sigcontext to be more useful Rather than just using pt_regs, it now contains the actual saved state explicitly, similar to pt_regs. By doing it this way, we provide a cleaner API for userspace (or equivalently, we avoid the need for libc to provide its own definition of sigcontext). While we're at it, move PT_FLAGS_xxx to where they are not visible from userspace. And always pass siginfo and mcontext to signal handlers, even if they claim they don't need it, since sometimes they actually try to use it anyway in practice. Signed-off-by: Chris Metcalf --- arch/tile/include/asm/ptrace.h | 15 ++++++--------- arch/tile/include/asm/sigcontext.h | 18 +++++++++++++----- arch/tile/include/asm/signal.h | 1 + arch/tile/kernel/signal.c | 27 +++++++++++++++------------ arch/tile/kernel/stack.c | 2 +- 5 files changed, 36 insertions(+), 27 deletions(-) (limited to 'arch/tile/kernel/stack.c') diff --git a/arch/tile/include/asm/ptrace.h b/arch/tile/include/asm/ptrace.h index acdae814e01..4a02bb07397 100644 --- a/arch/tile/include/asm/ptrace.h +++ b/arch/tile/include/asm/ptrace.h @@ -51,10 +51,7 @@ typedef uint_reg_t pt_reg_t; /* * This struct defines the way the registers are stored on the stack during a - * system call/exception. It should be a multiple of 8 bytes to preserve - * normal stack alignment rules. - * - * Must track and + * system call or exception. "struct sigcontext" has the same shape. */ struct pt_regs { /* Saved main processor registers; 56..63 are special. */ @@ -80,11 +77,6 @@ struct pt_regs { #endif /* __ASSEMBLY__ */ -/* Flag bits in pt_regs.flags */ -#define PT_FLAGS_DISABLE_IRQ 1 /* on return to kernel, disable irqs */ -#define PT_FLAGS_CALLER_SAVES 2 /* caller-save registers are valid */ -#define PT_FLAGS_RESTORE_REGS 4 /* restore callee-save regs on return */ - #define PTRACE_GETREGS 12 #define PTRACE_SETREGS 13 #define PTRACE_GETFPREGS 14 @@ -101,6 +93,11 @@ struct pt_regs { #ifdef __KERNEL__ +/* Flag bits in pt_regs.flags */ +#define PT_FLAGS_DISABLE_IRQ 1 /* on return to kernel, disable irqs */ +#define PT_FLAGS_CALLER_SAVES 2 /* caller-save registers are valid */ +#define PT_FLAGS_RESTORE_REGS 4 /* restore callee-save regs on return */ + #ifndef __ASSEMBLY__ #define instruction_pointer(regs) ((regs)->pc) diff --git a/arch/tile/include/asm/sigcontext.h b/arch/tile/include/asm/sigcontext.h index 7cd7672e3ad..5e2d03336f5 100644 --- a/arch/tile/include/asm/sigcontext.h +++ b/arch/tile/include/asm/sigcontext.h @@ -15,13 +15,21 @@ #ifndef _ASM_TILE_SIGCONTEXT_H #define _ASM_TILE_SIGCONTEXT_H -/* NOTE: we can't include due to #include dependencies. */ -#include - -/* Must track */ +#include +/* + * struct sigcontext has the same shape as struct pt_regs, + * but is simplified since we know the fault is from userspace. + */ struct sigcontext { - struct pt_regs regs; + uint_reg_t gregs[53]; /* General-purpose registers. */ + uint_reg_t tp; /* Aliases gregs[TREG_TP]. */ + uint_reg_t sp; /* Aliases gregs[TREG_SP]. */ + uint_reg_t lr; /* Aliases gregs[TREG_LR]. */ + uint_reg_t pc; /* Program counter. */ + uint_reg_t ics; /* In Interrupt Critical Section? */ + uint_reg_t faultnum; /* Fault number. */ + uint_reg_t pad[5]; }; #endif /* _ASM_TILE_SIGCONTEXT_H */ diff --git a/arch/tile/include/asm/signal.h b/arch/tile/include/asm/signal.h index eb0253f3220..c1ee1d61d44 100644 --- a/arch/tile/include/asm/signal.h +++ b/arch/tile/include/asm/signal.h @@ -24,6 +24,7 @@ #include #if defined(__KERNEL__) && !defined(__ASSEMBLY__) +struct pt_regs; int restore_sigcontext(struct pt_regs *, struct sigcontext __user *, long *); int setup_sigcontext(struct sigcontext __user *, struct pt_regs *); void do_signal(struct pt_regs *regs); diff --git a/arch/tile/kernel/signal.c b/arch/tile/kernel/signal.c index 45b66a3c991..ce183aa1492 100644 --- a/arch/tile/kernel/signal.c +++ b/arch/tile/kernel/signal.c @@ -61,13 +61,19 @@ int restore_sigcontext(struct pt_regs *regs, /* Always make any pending restarted system calls return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; + /* + * Enforce that sigcontext is like pt_regs, and doesn't mess + * up our stack alignment rules. + */ + BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs)); + BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0); + for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i) - err |= __get_user(((long *)regs)[i], - &((long __user *)(&sc->regs))[i]); + err |= __get_user(regs->regs[i], &sc->gregs[i]); regs->faultnum = INT_SWINT_1_SIGRETURN; - err |= __get_user(*pr0, &sc->regs.regs[0]); + err |= __get_user(*pr0, &sc->gregs[0]); return err; } @@ -112,8 +118,7 @@ int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs) int i, err = 0; for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i) - err |= __put_user(((long *)regs)[i], - &((long __user *)(&sc->regs))[i]); + err |= __put_user(regs->regs[i], &sc->gregs[i]); return err; } @@ -203,19 +208,17 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, * Set up registers for signal handler. * Registers that we don't modify keep the value they had from * user-space at the time we took the signal. + * We always pass siginfo and mcontext, regardless of SA_SIGINFO, + * since some things rely on this (e.g. glibc's debug/segfault.c). */ regs->pc = (unsigned long) ka->sa.sa_handler; regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */ regs->sp = (unsigned long) frame; regs->lr = restorer; regs->regs[0] = (unsigned long) usig; - - if (ka->sa.sa_flags & SA_SIGINFO) { - /* Need extra arguments, so mark to restore caller-saves. */ - regs->regs[1] = (unsigned long) &frame->info; - regs->regs[2] = (unsigned long) &frame->uc; - regs->flags |= PT_FLAGS_CALLER_SAVES; - } + regs->regs[1] = (unsigned long) &frame->info; + regs->regs[2] = (unsigned long) &frame->uc; + regs->flags |= PT_FLAGS_CALLER_SAVES; /* * Notify any tracer that was single-stepping it. diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c index 38a68b0b458..ea2e0ce2838 100644 --- a/arch/tile/kernel/stack.c +++ b/arch/tile/kernel/stack.c @@ -175,7 +175,7 @@ static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt) pr_err(" \n", frame->info.si_signo); } - return &frame->uc.uc_mcontext.regs; + return (struct pt_regs *)&frame->uc.uc_mcontext; } return NULL; } -- cgit v1.2.3-70-g09d2 From dabe98c972091818762e02841ab1f982e573e7d0 Mon Sep 17 00:00:00 2001 From: Chris Metcalf Date: Thu, 14 Oct 2010 15:19:04 -0400 Subject: arch/tile: prevent corrupt top frame from causing backtracer runaway The backtracer will normally cut itself off after 100 frames anyway, but it's messy. With this change we notice that the frame being reported is the same as the last one, and cut off the dump with a message similar to what gdb displays in the same circumstance. Signed-off-by: Chris Metcalf --- arch/tile/kernel/stack.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) (limited to 'arch/tile/kernel/stack.c') diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c index ea2e0ce2838..0d54106be3d 100644 --- a/arch/tile/kernel/stack.c +++ b/arch/tile/kernel/stack.c @@ -30,6 +30,10 @@ #include #include +#define KBT_ONGOING 0 /* Backtrace still ongoing */ +#define KBT_DONE 1 /* Backtrace cleanly completed */ +#define KBT_RUNNING 2 /* Can't run backtrace on a running task */ +#define KBT_LOOP 3 /* Backtrace entered a loop */ /* Is address on the specified kernel stack? */ static int in_kernel_stack(struct KBacktraceIterator *kbt, VirtualAddress sp) @@ -207,11 +211,11 @@ static int KBacktraceIterator_next_item_inclusive( for (;;) { do { if (!KBacktraceIterator_is_sigreturn(kbt)) - return 1; + return KBT_ONGOING; } while (backtrace_next(&kbt->it)); if (!KBacktraceIterator_restart(kbt)) - return 0; + return KBT_DONE; } } @@ -264,7 +268,7 @@ void KBacktraceIterator_init(struct KBacktraceIterator *kbt, kbt->pgtable = NULL; kbt->verbose = 0; /* override in caller if desired */ kbt->profile = 0; /* override in caller if desired */ - kbt->end = 0; + kbt->end = KBT_ONGOING; kbt->new_context = 0; if (is_current) { HV_PhysAddr pgdir_pa = hv_inquire_context().page_table; @@ -290,7 +294,7 @@ void KBacktraceIterator_init(struct KBacktraceIterator *kbt, if (regs == NULL) { if (is_current || t->state == TASK_RUNNING) { /* Can't do this; we need registers */ - kbt->end = 1; + kbt->end = KBT_RUNNING; return; } pc = get_switch_to_pc(); @@ -305,26 +309,29 @@ void KBacktraceIterator_init(struct KBacktraceIterator *kbt, } backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52); - kbt->end = !KBacktraceIterator_next_item_inclusive(kbt); + kbt->end = KBacktraceIterator_next_item_inclusive(kbt); } EXPORT_SYMBOL(KBacktraceIterator_init); int KBacktraceIterator_end(struct KBacktraceIterator *kbt) { - return kbt->end; + return kbt->end != KBT_ONGOING; } EXPORT_SYMBOL(KBacktraceIterator_end); void KBacktraceIterator_next(struct KBacktraceIterator *kbt) { + VirtualAddress old_pc = kbt->it.pc, old_sp = kbt->it.sp; kbt->new_context = 0; - if (!backtrace_next(&kbt->it) && - !KBacktraceIterator_restart(kbt)) { - kbt->end = 1; - return; - } - - kbt->end = !KBacktraceIterator_next_item_inclusive(kbt); + if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) { + kbt->end = KBT_DONE; + return; + } + kbt->end = KBacktraceIterator_next_item_inclusive(kbt); + if (old_pc == kbt->it.pc && old_sp == kbt->it.sp) { + /* Trapped in a loop; give up. */ + kbt->end = KBT_LOOP; + } } EXPORT_SYMBOL(KBacktraceIterator_next); @@ -387,6 +394,8 @@ void tile_show_stack(struct KBacktraceIterator *kbt, int headers) break; } } + if (kbt->end == KBT_LOOP) + pr_err("Stack dump stopped; next frame identical to this one\n"); if (headers) pr_err("Stack dump complete\n"); } -- cgit v1.2.3-70-g09d2