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authorHassan Naveed <hnaveed@wavecomp.com>2019-11-15 23:44:42 +0000
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-11-22 19:47:41 -0500
commit0e24220821b0e0e330a18bfef29ac6396545d62e (patch)
treeb184533336bdad135bc7f38b3c06bceaac9c661b /kernel/trace
parent89ed42495ef4a020435f2b999093bb5731eeb8b9 (diff)
downloadlinux-0e24220821b0e0e330a18bfef29ac6396545d62e.tar.bz2
tracing: Use xarray for syscall trace events
Currently, a lot of memory is wasted for architectures like MIPS when init_ftrace_syscalls() allocates the array for syscalls using kcalloc. This is because syscalls numbers start from 4000, 5000 or 6000 and array elements up to that point are unused. Fix this by using a data structure more suited to storing sparsely populated arrays. The XARRAY data structure, implemented using radix trees, is much more memory efficient for storing the syscalls in question. Link: http://lkml.kernel.org/r/20191115234314.21599-1-hnaveed@wavecomp.com Signed-off-by: Hassan Naveed <hnaveed@wavecomp.com> Reviewed-by: Paul Burton <paulburton@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace_syscalls.c32
1 files changed, 25 insertions, 7 deletions
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index fa8fbff736d6..16fa218556fa 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -7,6 +7,7 @@
#include <linux/module.h> /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
#include <linux/ftrace.h>
#include <linux/perf_event.h>
+#include <linux/xarray.h>
#include <asm/syscall.h>
#include "trace_output.h"
@@ -30,6 +31,7 @@ syscall_get_enter_fields(struct trace_event_call *call)
extern struct syscall_metadata *__start_syscalls_metadata[];
extern struct syscall_metadata *__stop_syscalls_metadata[];
+static DEFINE_XARRAY(syscalls_metadata_sparse);
static struct syscall_metadata **syscalls_metadata;
#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
@@ -101,6 +103,9 @@ find_syscall_meta(unsigned long syscall)
static struct syscall_metadata *syscall_nr_to_meta(int nr)
{
+ if (IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR))
+ return xa_load(&syscalls_metadata_sparse, (unsigned long)nr);
+
if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
return NULL;
@@ -536,12 +541,16 @@ void __init init_ftrace_syscalls(void)
struct syscall_metadata *meta;
unsigned long addr;
int i;
-
- syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
- GFP_KERNEL);
- if (!syscalls_metadata) {
- WARN_ON(1);
- return;
+ void *ret;
+
+ if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
+ syscalls_metadata = kcalloc(NR_syscalls,
+ sizeof(*syscalls_metadata),
+ GFP_KERNEL);
+ if (!syscalls_metadata) {
+ WARN_ON(1);
+ return;
+ }
}
for (i = 0; i < NR_syscalls; i++) {
@@ -551,7 +560,16 @@ void __init init_ftrace_syscalls(void)
continue;
meta->syscall_nr = i;
- syscalls_metadata[i] = meta;
+
+ if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
+ syscalls_metadata[i] = meta;
+ } else {
+ ret = xa_store(&syscalls_metadata_sparse, i, meta,
+ GFP_KERNEL);
+ WARN(xa_is_err(ret),
+ "Syscall memory allocation failed\n");
+ }
+
}
}