Re: [PATCH v4 5/8] powerpc: add exit_flags field in pt_regs
"Dmitry V. Levin" <[email protected]>
| Newsgroups | gmane.linux.ports.ppc.embedded,gmane.linux.kernel |
|---|---|
| Message-ID | <[email protected]> |
On Fri, Jan 23, 2026 at 01:09:13PM +0530, Mukesh Kumar Chaurasiya wrote: > From: Mukesh Kumar Chaurasiya <[email protected]> > > 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. > 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