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Add a patch for singlestep over atomic sequence on PPC

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This commit is contained in:
Petr Machata 2012-04-30 15:34:42 +02:00
parent 055adede18
commit 4fa0e1498d
2 changed files with 367 additions and 0 deletions
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365
ltrace-0.6.0-ppc-lwarx.patch Normal file
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@ -0,0 +1,365 @@
diff --git a/sysdeps/linux-gnu/ppc/arch.h b/sysdeps/linux-gnu/ppc/arch.h
index 711b4a3..64c1821 100644
--- a/sysdeps/linux-gnu/ppc/arch.h
+++ b/sysdeps/linux-gnu/ppc/arch.h
@@ -15,6 +15,7 @@
/* Start of arch-specific functions. */
#define ARCH_ENDIAN_BIG
+#define ARCH_HAVE_ATOMIC_SINGLESTEP
#define PPC_NOP { 0x60, 0x00, 0x00, 0x00 }
#define PPC_NOP_LENGTH 4
diff --git a/sysdeps/linux-gnu/ppc/trace.c b/sysdeps/linux-gnu/ppc/trace.c
index 8642157..05993de 100644
--- a/sysdeps/linux-gnu/ppc/trace.c
+++ b/sysdeps/linux-gnu/ppc/trace.c
@@ -197,3 +197,85 @@ arch_umovelong (Process *proc, void *addr, long *result, arg_type_info *info) {
memcpy(&arch->regs_copy, &arch->regs, sizeof(arch->regs));
memcpy(&arch->fpregs_copy, &arch->fpregs, sizeof(arch->fpregs));
}
+
+/* The atomic skip code is mostly taken from GDB. */
+
+/* Instruction masks used during single-stepping of atomic
+ * sequences. This was lifted from GDB. */
+#define LWARX_MASK 0xfc0007fe
+#define LWARX_INSTRUCTION 0x7c000028
+#define LDARX_INSTRUCTION 0x7c0000A8
+#define STWCX_MASK 0xfc0007ff
+#define STWCX_INSTRUCTION 0x7c00012d
+#define STDCX_INSTRUCTION 0x7c0001ad
+#define BC_MASK 0xfc000000
+#define BC_INSTRUCTION 0x40000000
+
+int
+arch_atomic_singlestep(struct Process *proc, struct breakpoint *sbp,
+ int (*add_cb)(void *addr, void *data),
+ void *add_cb_data)
+{
+ void *addr = sbp->addr;
+ debug(1, "pid=%d addr=%p", proc->pid, addr);
+
+ /* If the original instruction was lwarx/ldarx, we can't
+ * single-step over it, instead we have to execute the whole
+ * atomic block at once. */
+ union {
+ uint32_t insn;
+ char buf[4];
+ } u;
+ memcpy(u.buf, sbp->orig_value, BREAKPOINT_LENGTH);
+
+ if ((u.insn & LWARX_MASK) != LWARX_INSTRUCTION
+ && (u.insn & LWARX_MASK) != LDARX_INSTRUCTION)
+ return 1;
+
+ int insn_count;
+ for (insn_count = 0; ; ++insn_count) {
+ addr += 4;
+ unsigned long l = ptrace(PTRACE_PEEKTEXT, proc->pid, addr, 0);
+ if (l == (unsigned long)-1 && errno)
+ return -1;
+ uint32_t insn;
+#ifdef __powerpc64__
+ insn = l >> 32;
+#else
+ insn = l;
+#endif
+
+ /* If we hit a branch instruction, give up. The
+ * computation could escape that way and we'd have to
+ * treat that case specially. */
+ if ((insn & BC_MASK) == BC_INSTRUCTION) {
+ debug(1, "pid=%d, found branch at %p, giving up",
+ proc->pid, addr);
+ return -1;
+ }
+
+ if ((insn & STWCX_MASK) == STWCX_INSTRUCTION
+ || (insn & STWCX_MASK) == STDCX_INSTRUCTION) {
+ debug(1, "pid=%d, found end of atomic block at %p",
+ proc->pid, addr);
+ break;
+ }
+
+ /* Arbitrary cut-off. If we didn't find the
+ * terminating instruction by now, just give up. */
+ if (insn_count > 16) {
+ debug(1, "pid=%d, couldn't find end of atomic block",
+ proc->pid);
+ return -1;
+ }
+ }
+
+ /* Put the breakpoint to the next instruction. */
+ addr += 4;
+ if (add_cb(addr, add_cb_data) < 0)
+ return -1;
+
+ debug(1, "PTRACE_CONT");
+ ptrace(PTRACE_CONT, proc->pid, 0, 0);
+ return 0;
+}
diff --git a/sysdeps/linux-gnu/trace.c b/sysdeps/linux-gnu/trace.c
index 9ecea1e..d962048 100644
--- a/sysdeps/linux-gnu/trace.c
+++ b/sysdeps/linux-gnu/trace.c
@@ -249,6 +249,9 @@ struct process_stopping_handler
/* The pointer being re-enabled. */
struct breakpoint *breakpoint_being_enabled;
+ /* Artificial atomic skip breakpoint, if any needed. */
+ void *atomic_skip_bp_addr;
+
enum {
/* We are waiting for everyone to land in t/T. */
psh_stopping = 0,
@@ -612,12 +615,84 @@ all_stops_accountable(struct pid_set * pids)
return 1;
}
-static void
-singlestep(Process * proc)
+/* The protocol is: 0 for success, negative for failure, positive if
+ * default singlestep is to be used. */
+int arch_atomic_singlestep(struct Process *proc, struct breakpoint *sbp,
+ int (*add_cb)(void *addr, void *data),
+ void *add_cb_data);
+
+#ifndef ARCH_HAVE_ATOMIC_SINGLESTEP
+int
+arch_atomic_singlestep(struct Process *proc, struct breakpoint *sbp,
+ int (*add_cb)(void *addr, void *data),
+ void *add_cb_data)
+{
+ return 1;
+}
+#endif
+
+static int
+atomic_singlestep_add_bp(void *addr, void *data)
+{
+ struct process_stopping_handler *self = data;
+ struct Process *proc = self->task_enabling_breakpoint;
+
+ /* Only support single address as of now. */
+ assert(self->atomic_skip_bp_addr == NULL);
+
+ self->atomic_skip_bp_addr = addr + 4;
+ insert_breakpoint(proc->leader, self->atomic_skip_bp_addr, NULL, 1);
+
+ return 0;
+}
+
+static int
+singlestep(struct process_stopping_handler *self)
{
+ struct Process *proc = self->task_enabling_breakpoint;
+
+ int status = arch_atomic_singlestep(self->task_enabling_breakpoint,
+ self->breakpoint_being_enabled,
+ &atomic_singlestep_add_bp, self);
+
+ /* Propagate failure and success. */
+ if (status <= 0)
+ return status;
+
+ /* Otherwise do the default action: singlestep. */
debug(1, "PTRACE_SINGLESTEP");
- if (ptrace(PTRACE_SINGLESTEP, proc->pid, 0, 0))
+ if (ptrace(PTRACE_SINGLESTEP, proc->pid, 0, 0)) {
perror("PTRACE_SINGLESTEP");
+ return -1;
+ }
+ return 0;
+}
+
+static void
+post_singlestep(struct process_stopping_handler *self, Event **eventp)
+{
+ continue_for_sigstop_delivery(&self->pids);
+
+ if ((*eventp)->type == EVENT_BREAKPOINT)
+ *eventp = NULL; // handled
+
+ if (self->atomic_skip_bp_addr != 0)
+ delete_breakpoint(self->task_enabling_breakpoint->leader,
+ self->atomic_skip_bp_addr);
+
+ self->breakpoint_being_enabled = NULL;
+}
+
+static void
+singlestep_error(struct process_stopping_handler *self, Event **eventp)
+{
+ struct Process *teb = self->task_enabling_breakpoint;
+ struct breakpoint *sbp = self->breakpoint_being_enabled;
+ fprintf(stderr, "%d couldn't singlestep over %s (%p)\n",
+ teb->pid, sbp->libsym != NULL ? sbp->libsym->name : NULL,
+ sbp->addr);
+ delete_breakpoint(teb->leader, sbp->addr);
+ post_singlestep(self, eventp);
}
/* This event handler is installed when we are in the process of
@@ -670,7 +745,11 @@ process_stopping_on_event(Event_Handler * super, Event * event)
teb->pid);
if (sbp->enabled)
disable_breakpoint(teb, sbp);
- singlestep(teb);
+ if (singlestep(self) < 0) {
+ singlestep_error(self, &event);
+ goto psh_sinking;
+ }
+
self->state = state = psh_singlestep;
}
break;
@@ -682,7 +761,10 @@ process_stopping_on_event(Event_Handler * super, Event * event)
/* This is not the singlestep that we are waiting for. */
if (event->type == EVENT_SIGNAL) {
- singlestep(task);
+ if (singlestep(self) < 0) {
+ singlestep_error(self, &event);
+ goto psh_sinking;
+ }
break;
}
@@ -692,18 +774,13 @@ process_stopping_on_event(Event_Handler * super, Event * event)
if (sbp->enabled)
enable_breakpoint(teb, sbp);
- continue_for_sigstop_delivery(&self->pids);
-
- self->breakpoint_being_enabled = NULL;
- self->state = state = psh_sinking;
-
- if (event->type == EVENT_BREAKPOINT)
- event = NULL; // handled
- } else
- break;
-
- /* fall-through */
+ post_singlestep(self, &event);
+ goto psh_sinking;
+ }
+ break;
+ psh_sinking:
+ state = self->state = psh_sinking;
case psh_sinking:
if (await_sigstop_delivery(&self->pids, task_info, event))
process_stopping_done(self, leader);
diff --git a/testsuite/ltrace.torture/ppc-lwarx.c b/testsuite/ltrace.torture/ppc-lwarx.c
new file mode 100644
index 0000000..0716407
--- /dev/null
+++ b/testsuite/ltrace.torture/ppc-lwarx.c
@@ -0,0 +1,44 @@
+/*
+ * This file is part of ltrace.
+ * Copyright (C) 2012 Petr Machata, Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <stdint.h>
+
+__attribute__((noinline, optimize(3))) void
+atomic_add(uint32_t *a, uint32_t b)
+{
+ __asm__ volatile("lwarx 9,0,%0\n"
+ "add 9,9,%2\n"
+ "stwcx. 9,0,%0\n"
+ "bne- atomic_add\n"
+ : "=r"(a)
+ : "0"(a), "r"(b)
+ : "%r9");
+}
+
+uint32_t a = 0;
+
+__attribute__((optimize(0))) int
+main(int argc, char **argv)
+{
+ atomic_add(&a, 5);
+ atomic_add(&a, 10);
+ atomic_add(&a, 15);
+ return a;
+}
diff --git a/testsuite/ltrace.torture/ppc-lwarx.exp b/testsuite/ltrace.torture/ppc-lwarx.exp
new file mode 100644
index 0000000..bc2eba4
--- /dev/null
+++ b/testsuite/ltrace.torture/ppc-lwarx.exp
@@ -0,0 +1,55 @@
+# This file is part of ltrace.
+# Copyright (C) 2012 Petr Machata, Red Hat Inc.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; either version 2 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+set testfile "ppc-lwarx"
+set srcfile ${testfile}.c
+set binfile ${testfile}
+
+if [get_compiler_info $binfile] {
+ return -1
+}
+
+if { [istarget powerpc*-*] } then {
+ verbose "compiling source file now....."
+ if { [ltrace_compile $srcdir/$subdir/$srcfile $objdir/$subdir/$binfile executable {debug} ] != "" } {
+ send_user "Testcase compile failed, so all tests in this file will automatically fail\n."
+ }
+
+ # set options for ltrace.
+ ltrace_options "-x" "atomic_add" "-e" "!atoi"
+
+ # Run PUT for ltarce.
+ set exec_output [ltrace_runtest $objdir/$subdir $objdir/$subdir/$binfile]
+
+ # Check the output of this program.
+ verbose "ltrace runtest output: $exec_output\n"
+ if [regexp {ELF from incompatible architecture} $exec_output] {
+ fail "32-bit ltrace can not perform on 64-bit PUTs and rebuild ltrace in 64 bit mode!"
+ return
+ } elseif [ regexp {Couldn't get .hash data} $exec_output ] {
+ fail "Couldn't get .hash data!"
+ return
+ }
+
+ set pattern "atomic_add(.*, 5,.*)"
+ ltrace_verify_output ${objdir}/${subdir}/${testfile}.ltrace $pattern 1
+ set pattern "atomic_add(.*, 10,.*)"
+ ltrace_verify_output ${objdir}/${subdir}/${testfile}.ltrace $pattern 1
+ set pattern "atomic_add(.*, 15,.*)"
+ ltrace_verify_output ${objdir}/${subdir}/${testfile}.ltrace $pattern 1
+}

2
ltrace.spec
View File

@ -31,6 +31,7 @@ Patch13: ltrace-0.6.0-process-start.patch
Patch14: ltrace-0.6.0-selinux.patch
Patch15: ltrace-0.6.0-detach-sleeping.patch
Patch16: ltrace-0.6.0-tail-return.patch
Patch17: ltrace-0.6.0-ppc-lwarx.patch
%description
Ltrace is a debugging program which runs a specified command until the
@ -60,6 +61,7 @@ execution of processes.
%patch14 -p1
%patch15 -p1
%patch16 -p1
%patch17 -p1
sed -i -e 's/-o root -g root//' Makefile.in
%build