linux-kernel - [PATCH? v2] powerpc: Hard wire PT_SOFTE value to 1 in gpr

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Date:   Tue, 17 Sep 2019 16:37:53 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>
Cc:     Jan Kratochvil <jan.kratochvil@...hat.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH? v2] powerpc: Hard wire PT_SOFTE value to 1 in gpr_get() too

I don't have a ppc machine, this patch wasn't even compile tested,
could you please review?

The commit a8a4b03ab95f ("powerpc: Hard wire PT_SOFTE value to 1 in
ptrace & signals") changed ptrace_get_reg(PT_SOFTE) to report 0x1,
but PTRACE_GETREGS still copies pt_regs->softe as is.

This is not consistent and this breaks
http://sourceware.org/systemtap/wiki/utrace/tests/user-regs-peekpoke

Reported-by: Jan Kratochvil <jan.kratochvil@...hat.com>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 arch/powerpc/kernel/ptrace.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 8c92feb..291acfb 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -363,11 +363,36 @@ static int gpr_get(struct task_struct *target, const struct user_regset *regset,
 	BUILD_BUG_ON(offsetof(struct pt_regs, orig_gpr3) !=
 		     offsetof(struct pt_regs, msr) + sizeof(long));
 
+#ifdef CONFIG_PPC64
+	if (!ret)
+		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+					  &target->thread.regs->orig_gpr3,
+					  offsetof(struct pt_regs, orig_gpr3),
+					  offsetof(struct pt_regs, softe));
+
+	if (!ret) {
+		unsigned long softe = 0x1;
+		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &softe,
+					  offsetof(struct pt_regs, softe),
+					  offsetof(struct pt_regs, softe) +
+					  sizeof(softe));
+	}
+
+	BUILD_BUG_ON(offsetof(struct pt_regs, trap) !=
+		     offsetof(struct pt_regs, softe) + sizeof(long));
+
+	if (!ret)
+		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+					  &target->thread.regs->trap,
+					  offsetof(struct pt_regs, trap),
+					  sizeof(struct user_pt_regs));
+#else
 	if (!ret)
 		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 					  &target->thread.regs->orig_gpr3,
 					  offsetof(struct pt_regs, orig_gpr3),
 					  sizeof(struct user_pt_regs));
+#endif
 	if (!ret)
 		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
 					       sizeof(struct user_pt_regs), -1);
-- 
2.5.0