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powerpc: Split user/kernel definitions of struct pt_regs

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We use a shared definition for struct pt_regs in uapi/asm/ptrace.h.
That means the layout of the structure is ABI, ie. we can't change it.

That would be fine if it was only used to describe the user-visible
register state of a process, but it's also the struct we use in the
kernel to describe the registers saved in an interrupt frame.

We'd like more flexibility in the content (and possibly layout) of the
kernel version of the struct, but currently that's not possible.

So split the definition into a user-visible definition which remains
unchanged, and a kernel internal one.

At the moment they're still identical, and we check that at build
time. That's because we have code (in ptrace etc.) that assumes that
they are the same. We will fix that code in future patches, and then
we can break the strict symmetry between the two structs.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Michael Ellerman
2018-10-12 23:13:17 +11:00
parent 7f995d3ba6
commit 002af9391b
3 changed files with 72 additions and 1 deletions
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39
arch/powerpc/kernel/ptrace.c
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@@ -3335,3 +3335,42 @@ void do_syscall_trace_leave(struct pt_regs *regs)
user_enter();
}
void __init pt_regs_check(void)
{
BUILD_BUG_ON(offsetof(struct pt_regs, gpr) !=
offsetof(struct user_pt_regs, gpr));
BUILD_BUG_ON(offsetof(struct pt_regs, nip) !=
offsetof(struct user_pt_regs, nip));
BUILD_BUG_ON(offsetof(struct pt_regs, msr) !=
offsetof(struct user_pt_regs, msr));
BUILD_BUG_ON(offsetof(struct pt_regs, msr) !=
offsetof(struct user_pt_regs, msr));
BUILD_BUG_ON(offsetof(struct pt_regs, orig_gpr3) !=
offsetof(struct user_pt_regs, orig_gpr3));
BUILD_BUG_ON(offsetof(struct pt_regs, ctr) !=
offsetof(struct user_pt_regs, ctr));
BUILD_BUG_ON(offsetof(struct pt_regs, link) !=
offsetof(struct user_pt_regs, link));
BUILD_BUG_ON(offsetof(struct pt_regs, xer) !=
offsetof(struct user_pt_regs, xer));
BUILD_BUG_ON(offsetof(struct pt_regs, ccr) !=
offsetof(struct user_pt_regs, ccr));
#ifdef __powerpc64__
BUILD_BUG_ON(offsetof(struct pt_regs, softe) !=
offsetof(struct user_pt_regs, softe));
#else
BUILD_BUG_ON(offsetof(struct pt_regs, mq) !=
offsetof(struct user_pt_regs, mq));
#endif
BUILD_BUG_ON(offsetof(struct pt_regs, trap) !=
offsetof(struct user_pt_regs, trap));
BUILD_BUG_ON(offsetof(struct pt_regs, dar) !=
offsetof(struct user_pt_regs, dar));
BUILD_BUG_ON(offsetof(struct pt_regs, dsisr) !=
offsetof(struct user_pt_regs, dsisr));
BUILD_BUG_ON(offsetof(struct pt_regs, result) !=
offsetof(struct user_pt_regs, result));
BUILD_BUG_ON(sizeof(struct user_pt_regs) > sizeof(struct pt_regs));
}