Re: [PATCH v4 5/8] powerpc: add exit_flags field in pt_regs
From: Dmitry V. Levin <hidden>
Date: 2026-07-22 07:10:32
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On Fri, Jan 23, 2026 at 01:09:13PM +0530, Mukesh Kumar Chaurasiya wrote:
From: Mukesh Kumar Chaurasiya <redacted> Add a new field `exit_flags` in the pt_regs structure. This field will hold the flags set during interrupt or syscall execution that are required during exit to user mode.
Apparently, this change breaks PTRACE_GETREGS as the latter has no means to communicate the size of struct pt_regs being written to userspace. As result, the kernel with this patch will write to userpsace 32 more bytes than before, and unless the userspace is re-compiled with the latest ptrace.h, 32 bytes of userspace memory after struct pt_regs will be overwritten. This issue was detected by strace test suite, specifically, the test that checks whether the actual number of bytes written by ptrace(PTRACE_GETREGS) matches sizeof(struct pt_regs), and that test failed with runtime version v7.1 and headers version v7.2-rc1.
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/include/uapi/asm/ptrace.h b/arch/powerpc/include/uapi/asm/ptrace.h index 01e630149d48..a393b7f2760a 100644 --- a/arch/powerpc/include/uapi/asm/ptrace.h +++ b/arch/powerpc/include/uapi/asm/ptrace.h@@ -55,6 +55,8 @@ struct pt_regs unsigned long dar; /* Fault registers */ unsigned long dsisr; /* on 4xx/Book-E used for ESR */ unsigned long result; /* Result of a system call */ + unsigned long exit_flags; /* System call exit flags */ + unsigned long __pt_regs_pad[3]; /* Maintain 16 byte interrupt stack alignment */ }; #endif /* __ASSEMBLER__ */
-- ldv