commit 7797d17c591ae62c6f43c6de4fdb8beeb50eb692
author Will Deacon <will.deacon@arm.com> Thu Oct 11 12:10:57 2012 +0100
committer Catalin Marinas <catalin.marinas@arm.com> Thu Oct 18 20:15:31 2012 +0100
tree 168c3b4301ef6dedf1f9dbf73779986a49d934ca
parent 16dd46bb781a1d37eeb2377e8e48276e9d14d15d

arm64: ptrace: make structure padding explicit for debug registers

The user_hwdebug_state structure contains implicit padding to conform to
the alignment requirements of the AArch64 ABI (namely that aggregates
must be aligned to their most aligned member).

This patch fixes the ptrace functions operating on struct
user_hwdebug_state so that the padding is handled correctly.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/uapi/asm/ptrace.h

diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 9b131b4e..6913643 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -79,13 +79,14 @@
 
 struct user_hwdebug_state {
 	__u32		dbg_info;
+	__u32		pad;
 	struct {
 		__u64	addr;
 		__u32	ctrl;
+		__u32	pad;
 	}		dbg_regs[16];
 };
 
-
 #endif /* __ASSEMBLY__ */
 
 #endif /* _UAPI__ASM_PTRACE_H */

arch/arm64/kernel/ptrace.c

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 2ea3968..c62d39d 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -372,7 +372,7 @@
 
 #define PTRACE_HBP_ADDR_SZ	sizeof(u64)
 #define PTRACE_HBP_CTRL_SZ	sizeof(u32)
-#define PTRACE_HBP_REG_OFF	sizeof(u32)
+#define PTRACE_HBP_PAD_SZ	sizeof(u32)
 
 static int hw_break_get(struct task_struct *target,
 			const struct user_regset *regset,
@@ -380,7 +380,7 @@
 			void *kbuf, void __user *ubuf)
 {
 	unsigned int note_type = regset->core_note_type;
-	int ret, idx = 0, offset = PTRACE_HBP_REG_OFF, limit;
+	int ret, idx = 0, offset, limit;
 	u32 info, ctrl;
 	u64 addr;
 
@@ -389,11 +389,20 @@
 	if (ret)
 		return ret;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &info, 0, 4);
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &info, 0,
+				  sizeof(info));
+	if (ret)
+		return ret;
+
+	/* Pad */
+	offset = offsetof(struct user_hwdebug_state, pad);
+	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, offset,
+				       offset + PTRACE_HBP_PAD_SZ);
 	if (ret)
 		return ret;
 
 	/* (address, ctrl) registers */
+	offset = offsetof(struct user_hwdebug_state, dbg_regs);
 	limit = regset->n * regset->size;
 	while (count && offset < limit) {
 		ret = ptrace_hbp_get_addr(note_type, target, idx, &addr);
@@ -413,6 +422,13 @@
 		if (ret)
 			return ret;
 		offset += PTRACE_HBP_CTRL_SZ;
+
+		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
+					       offset,
+					       offset + PTRACE_HBP_PAD_SZ);
+		if (ret)
+			return ret;
+		offset += PTRACE_HBP_PAD_SZ;
 		idx++;
 	}
 
@@ -425,12 +441,13 @@
 			const void *kbuf, const void __user *ubuf)
 {
 	unsigned int note_type = regset->core_note_type;
-	int ret, idx = 0, offset = PTRACE_HBP_REG_OFF, limit;
+	int ret, idx = 0, offset, limit;
 	u32 ctrl;
 	u64 addr;
 
-	/* Resource info */
-	ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, 0, 4);
+	/* Resource info and pad */
+	offset = offsetof(struct user_hwdebug_state, dbg_regs);
+	ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, 0, offset);
 	if (ret)
 		return ret;
 
@@ -454,6 +471,13 @@
 		if (ret)
 			return ret;
 		offset += PTRACE_HBP_CTRL_SZ;
+
+		ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
+						offset,
+						offset + PTRACE_HBP_PAD_SZ);
+		if (ret)
+			return ret;
+		offset += PTRACE_HBP_PAD_SZ;
 		idx++;
 	}