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-rw-r--r--arch/Kconfig8
-rw-r--r--kernel/trace/trace_syscalls.c32
2 files changed, 33 insertions, 7 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 5f8a5d84dbbe..69c87e8608d8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -960,6 +960,14 @@ config RELR
config ARCH_HAS_MEM_ENCRYPT
bool
+config HAVE_SPARSE_SYSCALL_NR
+ bool
+ help
+ An architecture should select this if its syscall numbering is sparse
+ to save space. For example, MIPS architecture has a syscall array with
+ entries at 4000, 5000 and 6000 locations. This option turns on syscall
+ related optimizations for a given architecture.
+
source "kernel/gcov/Kconfig"
source "scripts/gcc-plugins/Kconfig"
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");
+ }
+
}
}