Commit 0515e5999a466dfe ("bpf: introduce BPF_PROG_TYPE_PERF_EVENT
program type") introduced the bpf_perf_event_data structure which
exports the pt_regs structure. This is OK for multiple architectures
but fail for s390 and arm64 which do not export pt_regs. Programs
using them, for example, the bpf selftest fail to compile on these
architectures.
For s390, exporting the pt_regs is not an option because s390 wants
to allow changes to it. For arm64, there is a user_pt_regs structure
that covers parts of the pt_regs structure for use by user space.
To solve the broken uapi for s390 and arm64, introduce an abstract
type for pt_regs and add an asm/bpf_perf_event.h file that concretes
the type. An asm-generic header file covers the architectures that
export pt_regs today.
The arch-specific enablement for s390 and arm64 follows in separate
commits.
Reported-by: Thomas Richter <tmricht@xxxxxxxxxxxxxxxxxx>
Fixes: 0515e5999a466dfe ("bpf: introduce BPF_PROG_TYPE_PERF_EVENT program type")
Signed-off-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx>
Reviewed-and-tested-by: Thomas Richter <tmricht@xxxxxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
---
include/linux/perf_event.h | 6 +++++-
include/uapi/asm-generic/bpf_perf_event.h | 9 +++++++++
include/uapi/linux/bpf_perf_event.h | 5 ++---
kernel/events/core.c | 2 +-
4 files changed, 17 insertions(+), 5 deletions(-)
create mode 100644 include/uapi/asm-generic/bpf_perf_event.h
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2c9c87d..7546822 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -15,6 +15,7 @@
#define _LINUX_PERF_EVENT_H
#include <uapi/linux/perf_event.h>
+#include <uapi/linux/bpf_perf_event.h>
/*
* Kernel-internal data types and definitions:
@@ -787,7 +788,7 @@ struct perf_output_handle {
};
struct bpf_perf_event_data_kern {
- struct pt_regs *regs;
+ bpf_user_pt_regs_t *regs;
struct perf_sample_data *data;
struct perf_event *event;
};
@@ -1177,6 +1178,9 @@ extern void perf_tp_event(u16 event_type, u64 count, void *record,
(user_mode(regs) ? PERF_RECORD_MISC_USER : PERF_RECORD_MISC_KERNEL)
# define perf_instruction_pointer(regs) instruction_pointer(regs)
#endif
+#ifndef perf_arch_bpf_user_pt_regs
+# define perf_arch_bpf_user_pt_regs(regs) regs
+#endif
static inline bool has_branch_stack(struct perf_event *event)
{
diff --git a/include/uapi/asm-generic/bpf_perf_event.h b/include/uapi/asm-generic/bpf_perf_event.h
new file mode 100644
index 0000000..53815d2
--- /dev/null
+++ b/include/uapi/asm-generic/bpf_perf_event.h
@@ -0,0 +1,9 @@
+#ifndef _UAPI__ASM_GENERIC_BPF_PERF_EVENT_H__
+#define _UAPI__ASM_GENERIC_BPF_PERF_EVENT_H__
+
+#include <linux/ptrace.h>
+
+/* Export kernel pt_regs structure */
+typedef struct pt_regs bpf_user_pt_regs_t;
+
+#endif /* _UAPI__ASM_GENERIC_BPF_PERF_EVENT_H__ */
diff --git a/include/uapi/linux/bpf_perf_event.h b/include/uapi/linux/bpf_perf_event.h
index af549d4..8f95303 100644
--- a/include/uapi/linux/bpf_perf_event.h
+++ b/include/uapi/linux/bpf_perf_event.h
@@ -8,11 +8,10 @@
#ifndef _UAPI__LINUX_BPF_PERF_EVENT_H__
#define _UAPI__LINUX_BPF_PERF_EVENT_H__
-#include <linux/types.h>
-#include <linux/ptrace.h>
+#include <asm/bpf_perf_event.h>
struct bpf_perf_event_data {
- struct pt_regs regs;
+ bpf_user_pt_regs_t regs;
__u64 sample_period;
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 16beab4..ba957b9 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7987,11 +7987,11 @@ static void bpf_overflow_handler(struct perf_event *event,
{
struct bpf_perf_event_data_kern ctx = {
.data = data,
- .regs = regs,
.event = event,
};
int ret = 0;
+ ctx.regs = perf_arch_bpf_user_pt_regs(regs);
preempt_disable();
if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
goto out;
--
1.8.3.1
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