[PATCH] x86: Include asm/ptrace.h in syscall_wrapper header

Jiri Olsa
2022-10-18T12:27:20Z

From: Jiri Olsa <olsajiri@gmail.com>

With just the forward declaration of the 'struct pt_regs' in
syscall_wrapper.h, the syscall stub functions:

__[x64|ia32]_sys_*(struct pt_regs *regs)

will have different definition of 'regs' argument in BTF data
based on which object file they are defined in.

If the syscall's object includes 'struct pt_regs' definition,
the BTF argument data will point to 'struct pt_regs' record,
like:

[226] STRUCT 'pt_regs' size=168 vlen=21
'r15' type_id=1 bits_offset=0
'r14' type_id=1 bits_offset=64
'r13' type_id=1 bits_offset=128
...

If not, it will point to fwd declaration record:

[15439] FWD 'pt_regs' fwd_kind=struct

and make bpf tracing program hooking on those functions unable
to access fields from 'struct pt_regs'.

Including asm/ptrace.h directly in syscall_wrapper.h to make
sure all syscalls see 'struct pt_regs' definition and resulted
BTF for '__*_sys_*(struct pt_regs *regs)' functions point to
actual struct, not just forward declaration.

Reported-by: Akihiro HARAI <jharai0815@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
arch/x86/include/asm/syscall_wrapper.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h
index 59358d1bf880..fd2669b1cb2d 100644
--- a/arch/x86/include/asm/syscall_wrapper.h
+++ b/arch/x86/include/asm/syscall_wrapper.h
@@ -6,7 +6,7 @@
#ifndef _ASM_X86_SYSCALL_WRAPPER_H
#define _ASM_X86_SYSCALL_WRAPPER_H

-struct pt_regs;
+#include <asm/ptrace.h>

extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
--
2.37.3