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Message-Id: <1587120160-3030-7-git-send-email-alan.maguire@oracle.com>
Date: Fri, 17 Apr 2020 11:42:40 +0100
From: Alan Maguire <alan.maguire@...cle.com>
To: ast@...nel.org, daniel@...earbox.net, yhs@...com
Cc: kafai@...com, songliubraving@...com, andriin@...com,
john.fastabend@...il.com, kpsingh@...omium.org,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
bpf@...r.kernel.org, Alan Maguire <alan.maguire@...cle.com>
Subject: [RFC PATCH bpf-next 6/6] printk: extend test_printf to test %pT BTF-based format specifier
Add tests to verify basic types and to iterate through all
enums, structs, unions and typedefs ensuring expected behaviour
occurs. Since test_printf can be built as a module we need to
export a BTF kind iterator function to allow us to iterate over
all names of a particular BTF kind.
These changes add up to approximately 10,000 new tests covering
all enum, struct, union and typedefs in vmlinux BTF.
Signed-off-by: Alan Maguire <alan.maguire@...cle.com>
---
include/linux/btf.h | 10 +++++
kernel/bpf/btf.c | 35 ++++++++++++++++
lib/test_printf.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+)
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 456bd8f..ef66d2e 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -177,4 +177,14 @@ static inline const char *btf_name_by_offset(const struct btf *btf,
}
#endif
+/* Following function used for testing BTF-based printk-family support */
+#ifdef CONFIG_BTF_PRINTF
+const char *btf_vmlinux_next_type_name(u8 kind, s32 *id);
+#else
+static inline const char *btf_vmlinux_next_type_name(u8 kind, s32 *id)
+{
+ return NULL;
+}
+#endif /* CONFIG_BTF_PRINTF */
+
#endif
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index ae453f0..0703d1d 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4867,3 +4867,38 @@ u32 btf_id(const struct btf *btf)
{
return btf->id;
}
+
+#ifdef CONFIG_BTF_PRINTF
+/*
+ * btf_vmlinux_next_type_name(): used in test_printf.c to
+ * iterate over types for testing.
+ * Exported as test_printf can be built as a module.
+ *
+ * @kind: BTF_KIND_* value
+ * @id: pointer to last id; value/result argument. When next
+ * type name is found, we set *id to associated id.
+ * Returns:
+ * Next type name, sets *id to associated id.
+ */
+const char *btf_vmlinux_next_type_name(u8 kind, s32 *id)
+{
+ const struct btf *btf = bpf_get_btf_vmlinux();
+ const struct btf_type *t;
+ const char *name;
+
+ if (!btf || !id)
+ return NULL;
+
+ for ((*id)++; *id <= btf->nr_types; (*id)++) {
+ t = btf->types[*id];
+ if (BTF_INFO_KIND(t->info) != kind)
+ continue;
+ name = btf_name_by_offset(btf, t->name_off);
+ if (name && strlen(name) > 0)
+ return name;
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(btf_vmlinux_next_type_name);
+#endif /* CONFIG_BTF_PRINTF */
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 2d9f520..9743e96 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -23,6 +23,9 @@
#include <linux/mm.h>
#include <linux/property.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/skbuff.h>
#include "../tools/testing/selftests/kselftest_module.h"
@@ -644,6 +647,120 @@ static void __init fwnode_pointer(void)
#endif
}
+#define __TEST_BTF(type, var, expected) test(expected, "%pT<"#type">", &var)
+
+#define TEST_BTF(type, var, ...) \
+ do { \
+ type var = __VA_ARGS__; \
+ pr_debug("type %s: %pT<" #type ">", #type, &var); \
+ __TEST_BTF(type, var, #__VA_ARGS__); \
+ } while (0)
+
+#define BTF_MAX_DATA_SIZE 8192
+#define BTF_MAX_BUF_SIZE (BTF_MAX_DATA_SIZE * 8)
+
+static void __init
+btf_print_kind(u8 kind, const char *kind_name)
+{
+ char fmt1[256], fmt2[256];
+ int res1, res2, res3;
+ const char *name;
+ u64 *dummy_data;
+ s32 id = 0;
+ char *buf;
+
+ dummy_data = kzalloc(BTF_MAX_DATA_SIZE, GFP_KERNEL);
+ buf = kzalloc(BTF_MAX_BUF_SIZE, GFP_KERNEL);
+ for (;;) {
+ name = btf_vmlinux_next_type_name(kind, &id);
+ if (!name)
+ break;
+
+ total_tests++;
+
+ strncpy(fmt1, "%pT<", sizeof(fmt1));
+ strncat(fmt1, kind_name, sizeof(fmt1));
+ strncat(fmt1, name, sizeof(fmt1));
+ strncat(fmt1, ">", sizeof(fmt1));
+
+ strncpy(fmt2, "%pTN<", sizeof(fmt2));
+ strncat(fmt2, kind_name, sizeof(fmt2));
+ strncat(fmt2, name, sizeof(fmt2));
+ strncat(fmt2, ">", sizeof(fmt2));
+
+ res1 = snprintf(buf, BTF_MAX_BUF_SIZE, fmt1, dummy_data);
+ res2 = snprintf(buf, 0, fmt1, dummy_data);
+ res3 = snprintf(buf, BTF_MAX_BUF_SIZE, fmt2, dummy_data);
+
+ /*
+ * Ensure return value is > 0 and identical irrespective
+ * of whether we pass in a big enough buffer;
+ * also ensure that printing names always results in as
+ * long/longer buffer length.
+ */
+ if (res1 <= 0 || res2 <= 0 || res3 <= 0) {
+ pr_warn("snprintf(%s%s); %d <= 0",
+ kind_name, name,
+ res1 <= 0 ? res1 : res2 <= 0 ? res2 : res3);
+ failed_tests++;
+ } else if (res1 != res2) {
+ pr_warn("snprintf(%s%s): %d != %d",
+ kind_name, name, res1, res2);
+ failed_tests++;
+ } else if (res3 < res2) {
+ pr_warn("snprintf(%s%s); %d < %d",
+ kind_name, name, res3, res2);
+ failed_tests++;
+ } else {
+ pr_debug("Printed %s%s (%d bytes, %d bytes with names)",
+ kind_name, name, res1, res3);
+ }
+ }
+ kfree(dummy_data);
+ kfree(buf);
+}
+
+static void __init
+btf_pointer(void)
+{
+ struct sk_buff *skb = alloc_skb(64, GFP_KERNEL);
+#ifdef CONFIG_BTF_PRINTF
+ TEST_BTF(int, testint, 0);
+ TEST_BTF(int, testint, 1234);
+ TEST_BTF(int, testint, -4567);
+ TEST_BTF(bool, testbool, 0);
+ TEST_BTF(bool, testbool, 1);
+ TEST_BTF(int64_t, testint64, 0);
+ TEST_BTF(int64_t, testint64, 1234);
+ TEST_BTF(int64_t, testint64, -4567);
+ TEST_BTF(char, testchar, 100);
+ TEST_BTF(enum bpf_arg_type, testenum, ARG_CONST_MAP_PTR);
+#endif /* CONFIG_BTF_PRINTF */
+
+ /*
+ * Iterate every instance of each kind, printing each associated type.
+ * This constitutes around 10k tests.
+ */
+ btf_print_kind(BTF_KIND_STRUCT, "struct ");
+ btf_print_kind(BTF_KIND_UNION, "union ");
+ btf_print_kind(BTF_KIND_ENUM, "enum ");
+ btf_print_kind(BTF_KIND_TYPEDEF, "");
+
+ /* verify unknown type falls back to hashed pointer display */
+ test_hashed("%pT<unknown_type>", NULL);
+ test_hashed("%pT<unknown_type>", skb);
+
+ /* verify use of unknown modifier X returns error string */
+ test("(%pT?)<unknown_type>", "%pTX<unknown_type>", skb);
+
+ /* No space separation is allowed other than for struct|enum|union */
+ test("(%pT?)", "%pT<invalid format>", skb);
+ /* Missing ">" format error */
+ test("(%pT?)", "%pT<struct sk_buff", skb);
+
+ kfree_skb(skb);
+}
+
static void __init
test_pointer(void)
{
@@ -668,6 +785,7 @@ static void __init fwnode_pointer(void)
flags();
errptr();
fwnode_pointer();
+ btf_pointer();
}
static void __init selftest(void)
--
1.8.3.1
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