[PATCH powerpc v2] powerpc/bpf: Fix use of user_pt_regs in uapi

From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH powerpc v2] powerpc/bpf: Fix use of user_pt_regs in uapi
Date: Tue, 28 Jun 2022 00:41:19 +0530	[thread overview]
Message-ID: <20220627191119.142867-1-naveen.n.rao@linux.vnet.ibm.com> (raw)

Trying to build a .c file that includes <linux/bpf_perf_event.h>:
  $ cat test_bpf_headers.c
  #include <linux/bpf_perf_event.h>

throws the below error:
  /usr/include/linux/bpf_perf_event.h:14:28: error: field ‘regs’ has incomplete type
     14 |         bpf_user_pt_regs_t regs;
	|                            ^~~~

This is because we typedef bpf_user_pt_regs_t to 'struct user_pt_regs'
in arch/powerpc/include/uaps/asm/bpf_perf_event.h, but 'struct
user_pt_regs' is not exposed to userspace.

Powerpc has both pt_regs and user_pt_regs structures. However, unlike
arm64 and s390, we expose user_pt_regs to userspace as just 'pt_regs'.
As such, we should typedef bpf_user_pt_regs_t to 'struct pt_regs' for
userspace.

Within the kernel though, we want to typedef bpf_user_pt_regs_t to
'struct user_pt_regs'.

Remove arch/powerpc/include/uapi/asm/bpf_perf_event.h so that the
uapi/asm-generic version of the header is exposed to userspace.
Introduce arch/powerpc/include/asm/bpf_perf_event.h so that we can
typedef bpf_user_pt_regs_t to 'struct user_pt_regs' for use within the
kernel.

Note that this was not showing up with the bpf selftest build since
tools/include/uapi/asm/bpf_perf_event.h didn't include the powerpc
variant.

Fixes: a6460b03f945ee ("powerpc/bpf: Fix broken uapi for BPF_PROG_TYPE_PERF_EVENT")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
v2: Add arch/powerpc/include/asm/bpf_perf_event.h

 arch/powerpc/include/asm/bpf_perf_event.h      | 9 +++++++++
 arch/powerpc/include/uapi/asm/bpf_perf_event.h | 9 ---------
 2 files changed, 9 insertions(+), 9 deletions(-)
 create mode 100644 arch/powerpc/include/asm/bpf_perf_event.h
 delete mode 100644 arch/powerpc/include/uapi/asm/bpf_perf_event.h

diff --git a/arch/powerpc/include/asm/bpf_perf_event.h b/arch/powerpc/include/asm/bpf_perf_event.h
new file mode 100644
index 00000000000000..a207467dd0a755
--- /dev/null
+++ b/arch/powerpc/include/asm/bpf_perf_event.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_BPF_PERF_EVENT_H
+#define _ASM_BPF_PERF_EVENT_H
+
+#include <asm/ptrace.h>
+
+typedef struct user_pt_regs bpf_user_pt_regs_t;
+
+#endif /* _ASM_BPF_PERF_EVENT_H */
diff --git a/arch/powerpc/include/uapi/asm/bpf_perf_event.h b/arch/powerpc/include/uapi/asm/bpf_perf_event.h
deleted file mode 100644
index 5e1e648aeec4c8..00000000000000
--- a/arch/powerpc/include/uapi/asm/bpf_perf_event.h
+++ /dev/null
@@ -1,9 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
-#ifndef _UAPI__ASM_BPF_PERF_EVENT_H__
-#define _UAPI__ASM_BPF_PERF_EVENT_H__
-
-#include <asm/ptrace.h>
-
-typedef struct user_pt_regs bpf_user_pt_regs_t;
-
-#endif /* _UAPI__ASM_BPF_PERF_EVENT_H__ */

base-commit: f85bb0e4405d64c657c3b10ca134bc8fff9afaaa
-- 
2.36.1

