1 files changed, 184 insertions, 134 deletions

diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index 2f822bb51717..b80437971d80 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -16,6 +16,7 @@
 
 #include <unistd.h>
 #include <linux/limits.h>
+#include <linux/socket.h>
 #include <pid_filter.h>
 
 /* bpf-output associated map */
@@ -33,6 +34,20 @@ struct syscall {
 
 bpf_map(syscalls, ARRAY, int, struct syscall, 512);
 
+/*
+ * What to augment at entry?
+ *
+ * Pointer arg payloads (filenames, etc) passed from userspace to the kernel
+ */
+bpf_map(syscalls_sys_enter, PROG_ARRAY, u32, u32, 512);
+
+/*
+ * What to augment at exit?
+ *
+ * Pointer arg payloads returned from the kernel (struct stat, etc) to userspace.
+ */
+bpf_map(syscalls_sys_exit, PROG_ARRAY, u32, u32, 512);
+
 struct syscall_enter_args {
 	unsigned long long common_tp_fields;
 	long		   syscall_nr;
@@ -45,7 +60,7 @@ struct syscall_exit_args {
 	long		   ret;
 };
 
-struct augmented_filename {
+struct augmented_arg {
 	unsigned int	size;
 	int		err;
 	char		value[PATH_MAX];
@@ -53,45 +68,176 @@ struct augmented_filename {
 
 pid_filter(pids_filtered);
 
-struct augmented_args_filename {
+struct augmented_args_payload {
        struct syscall_enter_args args;
-       struct augmented_filename filename;
+       union {
+		struct {
+			struct augmented_arg arg, arg2;
+		};
+		struct sockaddr_storage saddr;
+	};
 };
 
-bpf_map(augmented_filename_map, PERCPU_ARRAY, int, struct augmented_args_filename, 1);
+// We need more tmp space than the BPF stack can give us
+bpf_map(augmented_args_tmp, PERCPU_ARRAY, int, struct augmented_args_payload, 1);
+
+static inline struct augmented_args_payload *augmented_args_payload(void)
+{
+	int key = 0;
+	return bpf_map_lookup_elem(&augmented_args_tmp, &key);
+}
+
+static inline int augmented__output(void *ctx, struct augmented_args_payload *args, int len)
+{
+	/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */
+	return perf_event_output(ctx, &__augmented_syscalls__, BPF_F_CURRENT_CPU, args, len);
+}
 
 static inline
-unsigned int augmented_filename__read(struct augmented_filename *augmented_filename,
-				      const void *filename_arg, unsigned int filename_len)
+unsigned int augmented_arg__read_str(struct augmented_arg *augmented_arg, const void *arg, unsigned int arg_len)
 {
-	unsigned int len = sizeof(*augmented_filename);
-	int size = probe_read_str(&augmented_filename->value, filename_len, filename_arg);
+	unsigned int augmented_len = sizeof(*augmented_arg);
+	int string_len = probe_read_str(&augmented_arg->value, arg_len, arg);
 
-	augmented_filename->size = augmented_filename->err = 0;
+	augmented_arg->size = augmented_arg->err = 0;
 	/*
 	 * probe_read_str may return < 0, e.g. -EFAULT
-	 * So we leave that in the augmented_filename->size that userspace will
+	 * So we leave that in the augmented_arg->size that userspace will
 	 */
-	if (size > 0) {
-		len -= sizeof(augmented_filename->value) - size;
-		len &= sizeof(augmented_filename->value) - 1;
-		augmented_filename->size = size;
+	if (string_len > 0) {
+		augmented_len -= sizeof(augmented_arg->value) - string_len;
+		augmented_len &= sizeof(augmented_arg->value) - 1;
+		augmented_arg->size = string_len;
 	} else {
 		/*
 		 * So that username notice the error while still being able
 		 * to skip this augmented arg record
 		 */
-		augmented_filename->err = size;
-		len = offsetof(struct augmented_filename, value);
+		augmented_arg->err = string_len;
+		augmented_len = offsetof(struct augmented_arg, value);
 	}
 
-	return len;
+	return augmented_len;
+}
+
+SEC("!raw_syscalls:unaugmented")
+int syscall_unaugmented(struct syscall_enter_args *args)
+{
+	return 1;
+}
+
+/*
+ * These will be tail_called from SEC("raw_syscalls:sys_enter"), so will find in
+ * augmented_args_tmp what was read by that raw_syscalls:sys_enter and go
+ * on from there, reading the first syscall arg as a string, i.e. open's
+ * filename.
+ */
+SEC("!syscalls:sys_enter_connect")
+int sys_enter_connect(struct syscall_enter_args *args)
+{
+	struct augmented_args_payload *augmented_args = augmented_args_payload();
+	const void *sockaddr_arg = (const void *)args->args[1];
+	unsigned int socklen = args->args[2];
+	unsigned int len = sizeof(augmented_args->args);
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+	if (socklen > sizeof(augmented_args->saddr))
+		socklen = sizeof(augmented_args->saddr);
+
+	probe_read(&augmented_args->saddr, socklen, sockaddr_arg);
+
+	return augmented__output(args, augmented_args, len + socklen);
+}
+
+SEC("!syscalls:sys_enter_sendto")
+int sys_enter_sendto(struct syscall_enter_args *args)
+{
+	struct augmented_args_payload *augmented_args = augmented_args_payload();
+	const void *sockaddr_arg = (const void *)args->args[4];
+	unsigned int socklen = args->args[5];
+	unsigned int len = sizeof(augmented_args->args);
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+	if (socklen > sizeof(augmented_args->saddr))
+		socklen = sizeof(augmented_args->saddr);
+
+	probe_read(&augmented_args->saddr, socklen, sockaddr_arg);
+
+	return augmented__output(args, augmented_args, len + socklen);
+}
+
+SEC("!syscalls:sys_enter_open")
+int sys_enter_open(struct syscall_enter_args *args)
+{
+	struct augmented_args_payload *augmented_args = augmented_args_payload();
+	const void *filename_arg = (const void *)args->args[0];
+	unsigned int len = sizeof(augmented_args->args);
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+	len += augmented_arg__read_str(&augmented_args->arg, filename_arg, sizeof(augmented_args->arg.value));
+
+	return augmented__output(args, augmented_args, len);
+}
+
+SEC("!syscalls:sys_enter_openat")
+int sys_enter_openat(struct syscall_enter_args *args)
+{
+	struct augmented_args_payload *augmented_args = augmented_args_payload();
+	const void *filename_arg = (const void *)args->args[1];
+	unsigned int len = sizeof(augmented_args->args);
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+	len += augmented_arg__read_str(&augmented_args->arg, filename_arg, sizeof(augmented_args->arg.value));
+
+	return augmented__output(args, augmented_args, len);
+}
+
+SEC("!syscalls:sys_enter_rename")
+int sys_enter_rename(struct syscall_enter_args *args)
+{
+	struct augmented_args_payload *augmented_args = augmented_args_payload();
+	const void *oldpath_arg = (const void *)args->args[0],
+		   *newpath_arg = (const void *)args->args[1];
+	unsigned int len = sizeof(augmented_args->args), oldpath_len;
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+	oldpath_len = augmented_arg__read_str(&augmented_args->arg, oldpath_arg, sizeof(augmented_args->arg.value));
+	len += oldpath_len + augmented_arg__read_str((void *)(&augmented_args->arg) + oldpath_len, newpath_arg, sizeof(augmented_args->arg.value));
+
+	return augmented__output(args, augmented_args, len);
+}
+
+SEC("!syscalls:sys_enter_renameat")
+int sys_enter_renameat(struct syscall_enter_args *args)
+{
+	struct augmented_args_payload *augmented_args = augmented_args_payload();
+	const void *oldpath_arg = (const void *)args->args[1],
+		   *newpath_arg = (const void *)args->args[3];
+	unsigned int len = sizeof(augmented_args->args), oldpath_len;
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+	oldpath_len = augmented_arg__read_str(&augmented_args->arg, oldpath_arg, sizeof(augmented_args->arg.value));
+	len += oldpath_len + augmented_arg__read_str((void *)(&augmented_args->arg) + oldpath_len, newpath_arg, sizeof(augmented_args->arg.value));
+
+	return augmented__output(args, augmented_args, len);
 }
 
 SEC("raw_syscalls:sys_enter")
 int sys_enter(struct syscall_enter_args *args)
 {
-	struct augmented_args_filename *augmented_args;
+	struct augmented_args_payload *augmented_args;
 	/*
 	 * We start len, the amount of data that will be in the perf ring
 	 * buffer, if this is not filtered out by one of pid_filter__has(),
@@ -103,142 +249,46 @@ int sys_enter(struct syscall_enter_args *args)
 	 */
 	unsigned int len = sizeof(augmented_args->args);
 	struct syscall *syscall;
-	int key = 0;
-
-        augmented_args = bpf_map_lookup_elem(&augmented_filename_map, &key);
-        if (augmented_args == NULL)
-                return 1;
 
 	if (pid_filter__has(&pids_filtered, getpid()))
 		return 0;
 
+	augmented_args = augmented_args_payload();
+	if (augmented_args == NULL)
+		return 1;
+
 	probe_read(&augmented_args->args, sizeof(augmented_args->args), args);
 
-	syscall = bpf_map_lookup_elem(&syscalls, &augmented_args->args.syscall_nr);
-	if (syscall == NULL || !syscall->enabled)
-		return 0;
 	/*
-	 * Yonghong and Edward Cree sayz:
-	 *
-	 * https://www.spinics.net/lists/netdev/msg531645.html
-	 *
-	 * >>   R0=inv(id=0) R1=inv2 R6=ctx(id=0,off=0,imm=0) R7=inv64 R10=fp0,call_-1
-	 * >> 10: (bf) r1 = r6
-	 * >> 11: (07) r1 += 16
-	 * >> 12: (05) goto pc+2
-	 * >> 15: (79) r3 = *(u64 *)(r1 +0)
-	 * >> dereference of modified ctx ptr R1 off=16 disallowed
-	 * > Aha, we at least got a different error message this time.
-	 * > And indeed llvm has done that optimisation, rather than the more obvious
-	 * > 11: r3 = *(u64 *)(r1 +16)
-	 * > because it wants to have lots of reads share a single insn.  You may be able
-	 * > to defeat that optimisation by adding compiler barriers, idk.  Maybe someone
-	 * > with llvm knowledge can figure out how to stop it (ideally, llvm would know
-	 * > when it's generating for bpf backend and not do that).  -O0?  ¯\_(ツ)_/¯
-	 *
-	 * The optimization mostly likes below:
-	 *
-	 *	br1:
-	 * 	...
-	 *	r1 += 16
-	 *	goto merge
-	 *	br2:
-	 *	...
-	 *	r1 += 20
-	 *	goto merge
-	 *	merge:
-	 *	*(u64 *)(r1 + 0)
-	 *
-	 * The compiler tries to merge common loads. There is no easy way to
-	 * stop this compiler optimization without turning off a lot of other
-	 * optimizations. The easiest way is to add barriers:
-	 *
-	 * 	 __asm__ __volatile__("": : :"memory")
-	 *
-	 * 	 after the ctx memory access to prevent their down stream merging.
+	 * Jump to syscall specific augmenter, even if the default one,
+	 * "!raw_syscalls:unaugmented" that will just return 1 to return the
+	 * unagmented tracepoint payload.
 	 */
-	/*
-	 * For now copy just the first string arg, we need to improve the protocol
-	 * and have more than one.
-	 *
-	 * Using the unrolled loop is not working, only when we do it manually,
-	 * check this out later...
-
-	u8 arg;
-#pragma clang loop unroll(full)
-	for (arg = 0; arg < 6; ++arg) {
-		if (syscall->string_args_len[arg] != 0) {
-			filename_len = syscall->string_args_len[arg];
-			filename_arg = (const void *)args->args[arg];
-			__asm__ __volatile__("": : :"memory");
-			break;
-		}
-	}
-
-	verifier log:
-
-; if (syscall->string_args_len[arg] != 0) {
-37: (69) r3 = *(u16 *)(r0 +2)
- R0=map_value(id=0,off=0,ks=4,vs=14,imm=0) R1_w=inv0 R2_w=map_value(id=0,off=2,ks=4,vs=14,imm=0) R6=ctx(id=0,off=0,imm=0) R7=map_value(id=0,off=0,ks=4,vs=4168,imm=0) R10=fp0,call_-1 fp-8=mmmmmmmm
-; if (syscall->string_args_len[arg] != 0) {
-38: (55) if r3 != 0x0 goto pc+5
- R0=map_value(id=0,off=0,ks=4,vs=14,imm=0) R1=inv0 R2=map_value(id=0,off=2,ks=4,vs=14,imm=0) R3=inv0 R6=ctx(id=0,off=0,imm=0) R7=map_value(id=0,off=0,ks=4,vs=4168,imm=0) R10=fp0,call_-1 fp-8=mmmmmmmm
-39: (b7) r1 = 1
-; if (syscall->string_args_len[arg] != 0) {
-40: (bf) r2 = r0
-41: (07) r2 += 4
-42: (69) r3 = *(u16 *)(r0 +4)
- R0=map_value(id=0,off=0,ks=4,vs=14,imm=0) R1_w=inv1 R2_w=map_value(id=0,off=4,ks=4,vs=14,imm=0) R3_w=inv0 R6=ctx(id=0,off=0,imm=0) R7=map_value(id=0,off=0,ks=4,vs=4168,imm=0) R10=fp0,call_-1 fp-8=mmmmmmmm
-; if (syscall->string_args_len[arg] != 0) {
-43: (15) if r3 == 0x0 goto pc+32
- R0=map_value(id=0,off=0,ks=4,vs=14,imm=0) R1=inv1 R2=map_value(id=0,off=4,ks=4,vs=14,imm=0) R3=inv(id=0,umax_value=65535,var_off=(0x0; 0xffff)) R6=ctx(id=0,off=0,imm=0) R7=map_value(id=0,off=0,ks=4,vs=4168,imm=0) R10=fp0,call_-1 fp-8=mmmmmmmm
-; filename_arg = (const void *)args->args[arg];
-44: (67) r1 <<= 3
-45: (bf) r3 = r6
-46: (0f) r3 += r1
-47: (b7) r5 = 64
-48: (79) r3 = *(u64 *)(r3 +16)
-dereference of modified ctx ptr R3 off=8 disallowed
-processed 46 insns (limit 1000000) max_states_per_insn 0 total_states 12 peak_states 12 mark_read 7
-	*/
-
-#define __loop_iter(arg) \
-	if (syscall->string_args_len[arg] != 0) { \
-		unsigned int filename_len = syscall->string_args_len[arg]; \
-		const void *filename_arg = (const void *)args->args[arg]; \
-		if (filename_len <= sizeof(augmented_args->filename.value)) \
-			len += augmented_filename__read(&augmented_args->filename, filename_arg, filename_len);
-#define loop_iter_first() __loop_iter(0); }
-#define loop_iter(arg) else __loop_iter(arg); }
-#define loop_iter_last(arg) else __loop_iter(arg); __asm__ __volatile__("": : :"memory"); }
-
-	loop_iter_first()
-	loop_iter(1)
-	loop_iter(2)
-	loop_iter(3)
-	loop_iter(4)
-	loop_iter_last(5)
+	bpf_tail_call(args, &syscalls_sys_enter, augmented_args->args.syscall_nr);
 
-	/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */
-	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, augmented_args, len);
+	// If not found on the PROG_ARRAY syscalls map, then we're filtering it:
+	return 0;
 }
 
 SEC("raw_syscalls:sys_exit")
 int sys_exit(struct syscall_exit_args *args)
 {
 	struct syscall_exit_args exit_args;
-	struct syscall *syscall;
 
 	if (pid_filter__has(&pids_filtered, getpid()))
 		return 0;
 
 	probe_read(&exit_args, sizeof(exit_args), args);
-
-	syscall = bpf_map_lookup_elem(&syscalls, &exit_args.syscall_nr);
-	if (syscall == NULL || !syscall->enabled)
-		return 0;
-
-	return 1;
+	/*
+	 * Jump to syscall specific return augmenter, even if the default one,
+	 * "!raw_syscalls:unaugmented" that will just return 1 to return the
+	 * unagmented tracepoint payload.
+	 */
+	bpf_tail_call(args, &syscalls_sys_exit, exit_args.syscall_nr);
+	/*
+	 * If not found on the PROG_ARRAY syscalls map, then we're filtering it:
+	 */
+	return 0;
 }
 
 license(GPL);