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powerpc: Split user/kernel definitions of struct pt_regs 

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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27
arch/powerpc/include/asm/ptrace.h
View File

@ -26,6 +26,33 @@
#include <uapi/asm/ptrace.h>
#include <asm/asm-const.h>
#ifndef __ASSEMBLY__
struct pt_regs
{
union {
struct user_pt_regs user_regs;
struct {
unsigned long gpr[32];
unsigned long nip;
unsigned long msr;
unsigned long orig_gpr3;
unsigned long ctr;
unsigned long link;
unsigned long xer;
unsigned long ccr;
#ifdef CONFIG_PPC64
unsigned long softe;
#else
unsigned long mq;
#endif
unsigned long trap;
unsigned long dar;
unsigned long dsisr;
unsigned long result;
};
};
};
#endif
#ifdef __powerpc64__

7
arch/powerpc/include/uapi/asm/ptrace.h
View File

@ -29,7 +29,12 @@
#ifndef __ASSEMBLY__
struct pt_regs {
#ifdef __KERNEL__
struct user_pt_regs
#else
struct pt_regs
#endif
{
unsigned long gpr[32];
unsigned long nip;
unsigned long msr;

39
arch/powerpc/kernel/ptrace.c
View File

@ -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));
}