[lttng-dev] [PATCH] lttng-modules: Fixes for ARM and 32-bit systems
Trent Piepho
tpiepho at kymetacorp.com
Fri Mar 3 23:43:59 UTC 2017
Patch to fix recv() syscall missing in ARM syscall list.
Patch from lttng mailing list that fixes kernel timestamps being off
by about ~2 seconds on 32-bit systems. Additional patch to fix
compilation bug on non-X86 introduced by previous patch.
Signed-off-by: Trent Piepho <tpiepho at kymetacorp.com>
---
...trumentation-Add-recv-to-ARM-syscall-tabl.patch | 54 ++++++
...0002-Fix-nmi-safe-clock-on-32-bit-systems.patch | 188 +++++++++++++++++++++
...Fix-trace-clock-wrapper-to-compile-on-ARM.patch | 32 ++++
3 files changed, 274 insertions(+)
create mode 100644 package/lttng-modules/0001-syscall-instrumentation-Add-recv-to-ARM-syscall-tabl.patch
create mode 100644 package/lttng-modules/0002-Fix-nmi-safe-clock-on-32-bit-systems.patch
create mode 100644 package/lttng-modules/0003-Fix-trace-clock-wrapper-to-compile-on-ARM.patch
diff --git a/package/lttng-modules/0001-syscall-instrumentation-Add-recv-to-ARM-syscall-tabl.patch b/package/lttng-modules/0001-syscall-instrumentation-Add-recv-to-ARM-syscall-tabl.patch
new file mode 100644
index 0000000..f65a5d4
--- /dev/null
+++ b/package/lttng-modules/0001-syscall-instrumentation-Add-recv-to-ARM-syscall-tabl.patch
@@ -0,0 +1,54 @@
+From 318aba6e68e0338656909b207a96566c54becc85 Mon Sep 17 00:00:00 2001
+From: Trent Piepho <tpiepho at kymetacorp.com>
+Date: Wed, 22 Feb 2017 12:56:08 -0800
+Subject: [PATCH] syscall instrumentation: Add recv() to ARM syscall table
+
+This was missing for some reason.
+---
+ instrumentation/syscalls/3.4.25/arm-32-syscalls-3.4.25 | 1 +
+ .../syscalls/headers/arm-32-syscalls-3.4.25_pointers.h | 10 ++++++++++
+ 2 files changed, 11 insertions(+)
+
+diff --git a/instrumentation/syscalls/3.4.25/arm-32-syscalls-3.4.25 b/instrumentation/syscalls/3.4.25/arm-32-syscalls-3.4.25
+index 65c3973..c2e2429 100644
+--- a/instrumentation/syscalls/3.4.25/arm-32-syscalls-3.4.25
++++ b/instrumentation/syscalls/3.4.25/arm-32-syscalls-3.4.25
+@@ -221,6 +221,7 @@ syscall sys_getpeername nr 287 nbargs 3 types: (int, struct sockaddr *, int *) a
+ syscall sys_socketpair nr 288 nbargs 4 types: (int, int, int, int *) args: (family, type, protocol, usockvec)
+ syscall sys_send nr 289 nbargs 4 types: (int, void *, size_t, unsigned) args: (fd, buff, len, flags)
+ syscall sys_sendto nr 290 nbargs 6 types: (int, void *, size_t, unsigned, struct sockaddr *, int) args: (fd, buff, len, flags, addr, addr_len)
++syscall sys_recv nr 291 nbargs 4 types: (int, void *, size_t, unsigned int) args: (fd, ubuf, size, flags)
+ syscall sys_recvfrom nr 292 nbargs 6 types: (int, void *, size_t, unsigned, struct sockaddr *, int *) args: (fd, ubuf, size, flags, addr, addr_len)
+ syscall sys_shutdown nr 293 nbargs 2 types: (int, int) args: (fd, how)
+ syscall sys_setsockopt nr 294 nbargs 5 types: (int, int, int, char *, int) args: (fd, level, optname, optval, optlen)
+diff --git a/instrumentation/syscalls/headers/arm-32-syscalls-3.4.25_pointers.h b/instrumentation/syscalls/headers/arm-32-syscalls-3.4.25_pointers.h
+index 76aab1b..05aae76 100644
+--- a/instrumentation/syscalls/headers/arm-32-syscalls-3.4.25_pointers.h
++++ b/instrumentation/syscalls/headers/arm-32-syscalls-3.4.25_pointers.h
+@@ -1024,6 +1024,13 @@ SC_LTTNG_TRACEPOINT_EVENT(send,
+ TP_FIELDS(sc_exit(ctf_integer(long, ret, ret)) sc_inout(ctf_integer(int, fd, fd)) sc_inout(ctf_integer(void *, buff, buff)) sc_inout(ctf_integer(size_t, len, len)) sc_inout(ctf_integer(unsigned, flags, flags)))
+ )
+ #endif
++#ifndef OVERRIDE_32_recv
++SC_LTTNG_TRACEPOINT_EVENT(recv,
++ TP_PROTO(sc_exit(long ret,) int fd, void * ubuf, size_t size, unsigned int flags),
++ TP_ARGS(sc_exit(ret,) fd, ubuf, size, flags),
++ TP_FIELDS(sc_exit(ctf_integer(long, ret, ret)) sc_inout(ctf_integer(int, fd, fd)) sc_inout(ctf_integer(void *, ubuf, ubuf)) sc_inout(ctf_integer(size_t, size, size)) sc_inout(ctf_integer(unsigned int, flags, flags)))
++)
++#endif
+ #ifndef OVERRIDE_32_msgsnd
+ SC_LTTNG_TRACEPOINT_EVENT(msgsnd,
+ TP_PROTO(sc_exit(long ret,) int msqid, struct msgbuf * msgp, size_t msgsz, int msgflg),
+@@ -1762,6 +1769,9 @@ TRACE_SYSCALL_TABLE(send, send, 289, 4)
+ #ifndef OVERRIDE_TABLE_32_sendto
+ TRACE_SYSCALL_TABLE(sendto, sendto, 290, 6)
+ #endif
++#ifndef OVERRIDE_TABLE_32_recv
++TRACE_SYSCALL_TABLE(recv, recv, 291, 4)
++#endif
+ #ifndef OVERRIDE_TABLE_32_recvfrom
+ TRACE_SYSCALL_TABLE(recvfrom, recvfrom, 292, 6)
+ #endif
+--
+2.7.0.25.gfc10eb5.dirty
+
diff --git a/package/lttng-modules/0002-Fix-nmi-safe-clock-on-32-bit-systems.patch b/package/lttng-modules/0002-Fix-nmi-safe-clock-on-32-bit-systems.patch
new file mode 100644
index 0000000..91296b8
--- /dev/null
+++ b/package/lttng-modules/0002-Fix-nmi-safe-clock-on-32-bit-systems.patch
@@ -0,0 +1,188 @@
+From 412bf9d51784b49c71b3ddabb3fc0e2b89a59a97 Mon Sep 17 00:00:00 2001
+From: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+Date: Thu, 9 Feb 2017 20:51:29 -0500
+Subject: [PATCH] Fix: nmi-safe clock on 32-bit systems
+
+On 32-bit systems, the current algorithm assume to have one clock read
+per 32-bit LSB overflow period, which is not guaranteed. It also has an
+issue on the first clock reads after module load, because the initial
+value for the last LSB is 0. It can cause the time to stay stuck at the
+same value for a few seconds at the beginning of the trace.
+
+It only affects 32-bit systems with kernels >= 3.17.
+
+Fix this by using the non-nmi-safe clock source on 32-bit systems,
+except for x86 systems that support double-word cmpxchg (cmpxchg8b).
+
+Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+---
+ wrapper/trace-clock.c | 2 +-
+ wrapper/trace-clock.h | 82 +++++++++++++++++++--------------------------------
+ 2 files changed, 31 insertions(+), 53 deletions(-)
+
+diff --git a/wrapper/trace-clock.c b/wrapper/trace-clock.c
+index d9bc956..8c07942 100644
+--- a/wrapper/trace-clock.c
++++ b/wrapper/trace-clock.c
+@@ -24,7 +24,7 @@
+ #include <wrapper/trace-clock.h>
+
+ #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
+-DEFINE_PER_CPU(local_t, lttng_last_tsc);
++DEFINE_PER_CPU(struct lttng_last_timestamp, lttng_last_tsc);
+ EXPORT_PER_CPU_SYMBOL(lttng_last_tsc);
+ #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,16,0)) */
+
+diff --git a/wrapper/trace-clock.h b/wrapper/trace-clock.h
+index 496fec4..7f76b1b 100644
+--- a/wrapper/trace-clock.h
++++ b/wrapper/trace-clock.h
+@@ -59,65 +59,43 @@ extern struct lttng_trace_clock *lttng_trace_clock;
+ #define LTTNG_CLOCK_NMI_SAFE_BROKEN
+ #endif
+
++/*
++ * We need clock values to be monotonically increasing per-cpu, which is
++ * not strictly guaranteed by ktime_get_mono_fast_ns(). It is
++ * straightforward to do on architectures with a 64-bit cmpxchg(), but
++ * not so on architectures without 64-bit cmpxchg.
++ */
++
+ #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) \
++ && (BITS_PER_LONG == 64 || CONFIG_X86_CMPXCHG64) \
+ && !defined(LTTNG_CLOCK_NMI_SAFE_BROKEN))
++#define LTTNG_USE_NMI_SAFE_CLOCK
++#endif
+
+-DECLARE_PER_CPU(local_t, lttng_last_tsc);
++#ifdef LTTNG_USE_NMI_SAFE_CLOCK
+
+-#if (BITS_PER_LONG == 32)
+ /*
+- * Fixup "src_now" using the 32 LSB from "last". We need to handle overflow and
+- * underflow of the 32nd bit. "last" can be above, below or equal to the 32 LSB
+- * of "src_now".
++ * Ensure the variable is aligned on 64-bit for cmpxchg8b on 32-bit
++ * systems.
+ */
+-static inline u64 trace_clock_fixup(u64 src_now, u32 last)
+-{
+- u64 now;
++struct lttng_last_timestamp {
++ u64 v;
++} __attribute__((aligned(sizeof(u64))));
+
+- now = src_now & 0xFFFFFFFF00000000ULL;
+- now |= (u64) last;
+- /* Detect overflow or underflow between now and last. */
+- if ((src_now & 0x80000000U) && !(last & 0x80000000U)) {
+- /*
+- * If 32nd bit transitions from 1 to 0, and we move forward in
+- * time from "now" to "last", then we have an overflow.
+- */
+- if (((s32) now - (s32) last) < 0)
+- now += 0x0000000100000000ULL;
+- } else if (!(src_now & 0x80000000U) && (last & 0x80000000U)) {
+- /*
+- * If 32nd bit transitions from 0 to 1, and we move backward in
+- * time from "now" to "last", then we have an underflow.
+- */
+- if (((s32) now - (s32) last) > 0)
+- now -= 0x0000000100000000ULL;
+- }
+- return now;
+-}
+-#else /* #if (BITS_PER_LONG == 32) */
+-/*
+- * The fixup is pretty easy on 64-bit architectures: "last" is a 64-bit
+- * value, so we can use last directly as current time.
+- */
+-static inline u64 trace_clock_fixup(u64 src_now, u64 last)
+-{
+- return last;
+-}
+-#endif /* #else #if (BITS_PER_LONG == 32) */
++DECLARE_PER_CPU(struct lttng_last_timestamp, lttng_last_tsc);
+
+ /*
+ * Sometimes called with preemption enabled. Can be interrupted.
+ */
+ static inline u64 trace_clock_monotonic_wrapper(void)
+ {
+- u64 now;
+- unsigned long last, result;
+- local_t *last_tsc;
++ u64 now, last, result;
++ struct lttng_last_timestamp *last_tsc_ptr;
+
+ /* Use fast nmi-safe monotonic clock provided by the Linux kernel. */
+ preempt_disable();
+- last_tsc = lttng_this_cpu_ptr(<tng_last_tsc);
+- last = local_read(last_tsc);
++ last_tsc_ptr = lttng_this_cpu_ptr(<tng_last_tsc);
++ last = last_tsc_ptr->v;
+ /*
+ * Read "last" before "now". It is not strictly required, but it ensures
+ * that an interrupt coming in won't artificially trigger a case where
+@@ -126,9 +104,9 @@ static inline u64 trace_clock_monotonic_wrapper(void)
+ */
+ barrier();
+ now = ktime_get_mono_fast_ns();
+- if (((long) now - (long) last) < 0)
+- now = trace_clock_fixup(now, last);
+- result = local_cmpxchg(last_tsc, last, (unsigned long) now);
++ if (U64_MAX / 2 < now - last)
++ now = last;
++ result = cmpxchg64_local(&last_tsc_ptr->v, last, now);
+ preempt_enable();
+ if (result == last) {
+ /* Update done. */
+@@ -139,11 +117,11 @@ static inline u64 trace_clock_monotonic_wrapper(void)
+ * "result", since it has been sampled concurrently with our
+ * time read, so it should not be far from "now".
+ */
+- return trace_clock_fixup(now, result);
++ return result;
+ }
+ }
+
+-#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
++#else /* #ifdef LTTNG_USE_NMI_SAFE_CLOCK */
+ static inline u64 trace_clock_monotonic_wrapper(void)
+ {
+ ktime_t ktime;
+@@ -158,7 +136,7 @@ static inline u64 trace_clock_monotonic_wrapper(void)
+ ktime = ktime_get();
+ return ktime_to_ns(ktime);
+ }
+-#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
++#endif /* #else #ifdef LTTNG_USE_NMI_SAFE_CLOCK */
+
+ static inline u64 trace_clock_read64_monotonic(void)
+ {
+@@ -185,19 +163,19 @@ static inline const char *trace_clock_description_monotonic(void)
+ return "Monotonic Clock";
+ }
+
+-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
++#ifdef LTTNG_USE_NMI_SAFE_CLOCK
+ static inline int get_trace_clock(void)
+ {
+ printk_once(KERN_WARNING "LTTng: Using mainline kernel monotonic fast clock, which is NMI-safe.\n");
+ return 0;
+ }
+-#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
++#else /* #ifdef LTTNG_USE_NMI_SAFE_CLOCK */
+ static inline int get_trace_clock(void)
+ {
+ printk_once(KERN_WARNING "LTTng: Using mainline kernel monotonic clock. NMIs will not be traced.\n");
+ return 0;
+ }
+-#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
++#endif /* #else #ifdef LTTNG_USE_NMI_SAFE_CLOCK */
+
+ static inline void put_trace_clock(void)
+ {
+--
+2.7.0.25.gfc10eb5.dirty
+
diff --git a/package/lttng-modules/0003-Fix-trace-clock-wrapper-to-compile-on-ARM.patch b/package/lttng-modules/0003-Fix-trace-clock-wrapper-to-compile-on-ARM.patch
new file mode 100644
index 0000000..15708b8
--- /dev/null
+++ b/package/lttng-modules/0003-Fix-trace-clock-wrapper-to-compile-on-ARM.patch
@@ -0,0 +1,32 @@
+From f69bf94310f0da5ed1791b0da4c1420b235d4b8b Mon Sep 17 00:00:00 2001
+From: Trent Piepho <tpiepho at kymetacorp.com>
+Date: Fri, 3 Mar 2017 14:25:16 -0800
+Subject: [PATCH] Fix trace clock wrapper to compile on ARM
+
+The X86 only define isn't present. Just assume 64-bit cmpxcng works
+on all all the other architectures.
+---
+ wrapper/trace-clock.h | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/wrapper/trace-clock.h b/wrapper/trace-clock.h
+index 7f76b1b..066d5e6 100644
+--- a/wrapper/trace-clock.h
++++ b/wrapper/trace-clock.h
+@@ -66,8 +66,12 @@ extern struct lttng_trace_clock *lttng_trace_clock;
+ * not so on architectures without 64-bit cmpxchg.
+ */
+
++#if defined(ARCH_X86) && !defined(CONFIG_X86_CMPXCHG64)
++#define LTTNG_NO_CMPXCHG64
++#endif
++
+ #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) \
+- && (BITS_PER_LONG == 64 || CONFIG_X86_CMPXCHG64) \
++ && !defined(LTTNG_NO_CMPXCHG64) \
+ && !defined(LTTNG_CLOCK_NMI_SAFE_BROKEN))
+ #define LTTNG_USE_NMI_SAFE_CLOCK
+ #endif
+--
+2.7.0.25.gfc10eb5.dirty
+
--
2.7.0.25.gfc10eb5.dirty
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