selftests: new x86 breakpoints selftest

Bring a first selftest in the relevant directory.  This tests several
combinations of breakpoints and watchpoints in x86, as well as icebp traps
and int3 traps.  Given the amount of breakpoint regressions we raised
after we merged the generic breakpoint infrastructure, such selftest
became necessary and can still serve today as a basis for new patches that
touch the do_debug() path.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 416 insertions, 2 deletions

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 298a5c0c1ead..4ec84018cc13 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -1,4 +1,4 @@
-TARGETS =
+TARGETS = breakpoints
 
 all:
         for TARGET in $(TARGETS); do \
diff --git a/tools/testing/selftests/breakpoints/Makefile b/tools/testing/selftests/breakpoints/Makefile
new file mode 100644
index 000000000000..f362722cdce7
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/Makefile
@@ -0,0 +1,20 @@
+# Taken from perf makefile
+uname_M := $(shell uname -m 2>/dev/null || echo not)
+ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/)
+ifeq ($(ARCH),i386)
+        ARCH := x86
+endif
+ifeq ($(ARCH),x86_64)
+        ARCH := x86
+endif
+
+
+all:
+ifeq ($(ARCH),x86)
+        gcc breakpoint_test.c -o run_test
+else
+        echo "Not an x86 target, can't build breakpoints selftests"
+endif
+
+clean:
+        rm -fr run_test
diff --git a/tools/testing/selftests/breakpoints/breakpoint_test.c b/tools/testing/selftests/breakpoints/breakpoint_test.c
new file mode 100644
index 000000000000..a0743f3b2b57
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/breakpoint_test.c
@@ -0,0 +1,394 @@
+/*
+ * Copyright (C) 2011 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
+ *
+ * Licensed under the terms of the GNU GPL License version 2
+ *
+ * Selftests for breakpoints (and more generally the do_debug() path) in x86.
+ */
+
+
+#include <sys/ptrace.h>
+#include <unistd.h>
+#include <stddef.h>
+#include <sys/user.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+
+/* Breakpoint access modes */
+enum {
+        BP_X = 1,
+        BP_RW = 2,
+        BP_W = 4,
+};
+
+static pid_t child_pid;
+
+/*
+ * Ensures the child and parent are always "talking" about
+ * the same test sequence. (ie: that we haven't forgotten
+ * to call check_trapped() somewhere).
+ */
+static int nr_tests;
+
+static void set_breakpoint_addr(void *addr, int n)
+{
+        int ret;
+
+        ret = ptrace(PTRACE_POKEUSER, child_pid,
+                     offsetof(struct user, u_debugreg[n]), addr);
+        if (ret) {
+                perror("Can't set breakpoint addr\n");
+                exit(-1);
+        }
+}
+
+static void toggle_breakpoint(int n, int type, int len,
+                              int local, int global, int set)
+{
+        int ret;
+
+        int xtype, xlen;
+        unsigned long vdr7, dr7;
+
+        switch (type) {
+        case BP_X:
+                xtype = 0;
+                break;
+        case BP_W:
+                xtype = 1;
+                break;
+        case BP_RW:
+                xtype = 3;
+                break;
+        }
+
+        switch (len) {
+        case 1:
+                xlen = 0;
+                break;
+        case 2:
+                xlen = 4;
+                break;
+        case 4:
+                xlen = 0xc;
+                break;
+        case 8:
+                xlen = 8;
+                break;
+        }
+
+        dr7 = ptrace(PTRACE_PEEKUSER, child_pid,
+                     offsetof(struct user, u_debugreg[7]), 0);
+
+        vdr7 = (xlen | xtype) << 16;
+        vdr7 <<= 4 * n;
+
+        if (local) {
+                vdr7 |= 1 << (2 * n);
+                vdr7 |= 1 << 8;
+        }
+        if (global) {
+                vdr7 |= 2 << (2 * n);
+                vdr7 |= 1 << 9;
+        }
+
+        if (set)
+                dr7 |= vdr7;
+        else
+                dr7 &= ~vdr7;
+
+        ret = ptrace(PTRACE_POKEUSER, child_pid,
+                     offsetof(struct user, u_debugreg[7]), dr7);
+        if (ret) {
+                perror("Can't set dr7");
+                exit(-1);
+        }
+}
+
+/* Dummy variables to test read/write accesses */
+static unsigned long long dummy_var[4];
+
+/* Dummy functions to test execution accesses */
+static void dummy_func(void) { }
+static void dummy_func1(void) { }
+static void dummy_func2(void) { }
+static void dummy_func3(void) { }
+
+static void (*dummy_funcs[])(void) = {
+        dummy_func,
+        dummy_func1,
+        dummy_func2,
+        dummy_func3,
+};
+
+static int trapped;
+
+static void check_trapped(void)
+{
+        /*
+         * If we haven't trapped, wake up the parent
+         * so that it notices the failure.
+         */
+        if (!trapped)
+                kill(getpid(), SIGUSR1);
+        trapped = 0;
+
+        nr_tests++;
+}
+
+static void write_var(int len)
+{
+        char *pcval; short *psval; int *pival; long long *plval;
+        int i;
+