Subject: Re: [PATCH V4 7/8] powerpc, ptrace: Enable support for miscellaneous debug registers

From: Anshuman Khandual <[email-masked]>
Date: Thu, 13 Nov 2014 15:15:11 +0530

On 11/11/2014 10:56 AM, Anshuman Khandual wrote:
> This patch enables get and set of miscellaneous debug registers through
> ptrace PTRACE_GETREGSET-PTRACE_SETREGSET interface by implementing new
> powerpc specific register set REGSET_MISC support corresponding to the
> new ELF core note NT_PPC_MISC added previously in this regard.

Right now this one does not compile for "ppc64e_defconfig" and
"pmac32_defconfig" config options. The patch below will fix it
and would be part of next revision.

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 61a2581..be566eb 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1326,6 +1326,7 @@ static int tm_cvmx_set(struct task_struct *target,
 }
 #endif	/* CONFIG_PPC_TRANSACTIONAL_MEM */
 
+#ifdef CONFIG_PPC64
 /*
  * get_misc_dbg
  *
@@ -1339,6 +1340,9 @@ static int tm_cvmx_set(struct task_struct *target,
  *	unsigned long ppr;
  *	unsigned long tar;
  * };
+ *
+ * The data element 'tar' will be valid only if the
+ * kernel has CONFIG_PPC_BOOK3S_64 config option enabled.
  */
 static int get_misc_dbg(struct task_struct *target,
 			const struct user_regset *regset, unsigned int pos,
@@ -1348,7 +1352,10 @@ static int get_misc_dbg(struct task_struct *target,
 
 	/* Build test */
 	BUILD_BUG_ON(TSO(dscr) + 2 * sizeof(unsigned long) != TSO(ppr));
+
+#ifdef CONFIG_PPC_BOOK3S_64
 	BUILD_BUG_ON(TSO(ppr) + sizeof(unsigned long) != TSO(tar));
+#endif
 
 	/* DSCR register */
 	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
@@ -1362,12 +1369,14 @@ static int get_misc_dbg(struct task_struct *target,
 						sizeof(unsigned long),
 						2 * sizeof(unsigned long));
 
+#ifdef CONFIG_PPC_BOOK3S_64
 	/* TAR register */
 	if (!ret)
 		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 						&target->thread.tar,
 						2 * sizeof(unsigned long),
 						3 * sizeof(unsigned long));
+#endif
 	return ret;
 }
 
@@ -1384,6 +1393,9 @@ static int get_misc_dbg(struct task_struct *target,
  *	unsigned long ppr;
  *	unsigned long tar;
  * };
+ *
+ * The data element 'tar' will be valid only if the
+ * kernel has CONFIG_PPC_BOOK3S_64 config option enabled.
  */
 static int set_misc_dbg(struct task_struct *target,
 			const struct user_regset *regset, unsigned int pos,
@@ -1394,7 +1406,10 @@ static int set_misc_dbg(struct task_struct *target,
 
 	/* Build test */
 	BUILD_BUG_ON(TSO(dscr) + 2 * sizeof(unsigned long) != TSO(ppr));
+
+#ifdef CONFIG_PPC_BOOK3S_64
 	BUILD_BUG_ON(TSO(ppr) + sizeof(unsigned long) != TSO(tar));
+#endif
 
 	/* DSCR register */
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
@@ -1407,15 +1422,17 @@ static int set_misc_dbg(struct task_struct *target,
 						&target->thread.ppr,
 						sizeof(unsigned long),
 						2 * sizeof(unsigned long));
-
+#ifdef CONFIG_PPC_BOOK3S_64
 	/* TAR register */
 	if (!ret)
 		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 						&target->thread.tar,
 						2 * sizeof(unsigned long),
 						3 * sizeof(unsigned long));
+#endif
 	return ret;
 }
+#endif /* CONFIG_PPC64 */
 
 /*
  * These are our native regset flavors.
@@ -1438,7 +1455,9 @@ enum powerpc_regset {
 	REGSET_TM_CFPR,		/* TM checkpointed FPR registers */
 	REGSET_TM_CVMX,		/* TM checkpointed VMX registers */
 #endif
+#ifdef CONFIG_PPC64
 	REGSET_MISC		/* Miscellaneous debug registers */
+#endif
 };
 
 static const struct user_regset native_regsets[] = {
@@ -1495,11 +1514,13 @@ static const struct user_regset native_regsets[] = {
 		.active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
 	},
 #endif
+#ifdef CONFIG_PPC64
 	[REGSET_MISC] = {
 		.core_note_type = NT_PPC_MISC, .n = ELF_NMISCREG,
 		.size = sizeof(u64), .align = sizeof(u64),
 		.get = get_misc_dbg, .set = set_misc_dbg
 	},
+#endif
 };
 
 static const struct user_regset_view user_ppc_native_view = {