powerpc/signal32: Convert restore_[tm]_user_regs() to user access block

Convert restore_user_regs() and restore_tm_user_regs()
to use user_access_read_begin/end blocks.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/181adf15a6f644efcd1aeafb355f3578ff1b6bc5.1616151715.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/ptrace.h

@@ -245,7 +245,7 @@ static inline bool trap_norestart(struct pt_regs *regs)
 	return regs->trap & 0x10;
 }
 
-static inline void set_trap_norestart(struct pt_regs *regs)
+static __always_inline void set_trap_norestart(struct pt_regs *regs)
 {
 	regs->trap |= 0x10;
 }

arch/powerpc/kernel/signal_32.c

@@ -116,8 +116,8 @@ __unsafe_save_general_regs(struct pt_regs *regs, struct mcontext __user *frame)
 	return 1;
 }
 
-static inline int restore_general_regs(struct pt_regs *regs,
-		struct mcontext __user *sr)
+static __always_inline int
+__unsafe_restore_general_regs(struct pt_regs *regs, struct mcontext __user *sr)
 {
 	elf_greg_t64 *gregs = (elf_greg_t64 *)regs;
 	int i;
@@ -125,10 +125,12 @@ static inline int restore_general_regs(struct pt_regs *regs,
 	for (i = 0; i <= PT_RESULT; i++) {
 		if ((i == PT_MSR) || (i == PT_SOFTE))
 			continue;
-		if (__get_user(gregs[i], &sr->mc_gregs[i]))
-			return -EFAULT;
+		unsafe_get_user(gregs[i], &sr->mc_gregs[i], failed);
 	}
 	return 0;
+
+failed:
+	return 1;
 }
 
 #else /* CONFIG_PPC64 */
@@ -161,18 +163,20 @@ __unsafe_save_general_regs(struct pt_regs *regs, struct mcontext __user *frame)
 	return 1;
 }
 
-static inline int restore_general_regs(struct pt_regs *regs,
-		struct mcontext __user *sr)
+static __always_inline
+int __unsafe_restore_general_regs(struct pt_regs *regs, struct mcontext __user *sr)
 {
 	/* copy up to but not including MSR */
-	if (__copy_from_user(regs, &sr->mc_gregs,
-				PT_MSR * sizeof(elf_greg_t)))
-		return -EFAULT;
+	unsafe_copy_from_user(regs, &sr->mc_gregs, PT_MSR * sizeof(elf_greg_t), failed);
+
 	/* copy from orig_r3 (the word after the MSR) up to the end */
-	if (__copy_from_user(&regs->orig_gpr3, &sr->mc_gregs[PT_ORIG_R3],
-				GP_REGS_SIZE - PT_ORIG_R3 * sizeof(elf_greg_t)))
-		return -EFAULT;
+	unsafe_copy_from_user(&regs->orig_gpr3, &sr->mc_gregs[PT_ORIG_R3],
+			      GP_REGS_SIZE - PT_ORIG_R3 * sizeof(elf_greg_t), failed);
+
 	return 0;
+
+failed:
+	return 1;
 }
 #endif
 
@@ -181,6 +185,11 @@ static inline int restore_general_regs(struct pt_regs *regs,
 		goto label;					\
 } while (0)
 
+#define unsafe_restore_general_regs(regs, frame, label) do {	\
+	if (__unsafe_restore_general_regs(regs, frame))		\
+		goto label;					\
+} while (0)
+
 /*
  * When we have signals to deliver, we set up on the
  * user stack, going down from the original stack pointer:
@@ -485,14 +494,13 @@ static int save_tm_user_regs_unsafe(struct pt_regs *regs, struct mcontext __user
 static long restore_user_regs(struct pt_regs *regs,
 			      struct mcontext __user *sr, int sig)
 {
-	long err;
 	unsigned int save_r2 = 0;
 	unsigned long msr;
 #ifdef CONFIG_VSX
 	int i;
 #endif
 
-	if (!access_ok(sr, sizeof(*sr)))
+	if (!user_read_access_begin(sr, sizeof(*sr)))
 		return 1;
 	/*
 	 * restore general registers but not including MSR or SOFTE. Also
@@ -500,13 +508,11 @@ static long restore_user_regs(struct pt_regs *regs,
 	 */
 	if (!sig)
 		save_r2 = (unsigned int)regs->gpr[2];
-	err = restore_general_regs(regs, sr);
+	unsafe_restore_general_regs(regs, sr, failed);
 	set_trap_norestart(regs);
-	err |= __get_user(msr, &sr->mc_gregs[PT_MSR]);
+	unsafe_get_user(msr, &sr->mc_gregs[PT_MSR], failed);
 	if (!sig)
 		regs->gpr[2] = (unsigned long) save_r2;
-	if (err)
-		return 1;
 
 	/* if doing signal return, restore the previous little-endian mode */
 	if (sig)
@@ -520,22 +526,19 @@ static long restore_user_regs(struct pt_regs *regs,
 	regs->msr &= ~MSR_VEC;
 	if (msr & MSR_VEC) {
 		/* restore altivec registers from the stack */
-		if (__copy_from_user(&current->thread.vr_state, &sr->mc_vregs,
-				     sizeof(sr->mc_vregs)))
-			return 1;
+		unsafe_copy_from_user(&current->thread.vr_state, &sr->mc_vregs,
+				      sizeof(sr->mc_vregs), failed);
 		current->thread.used_vr = true;
 	} else if (current->thread.used_vr)
 		memset(&current->thread.vr_state, 0,
 		       ELF_NVRREG * sizeof(vector128));
 
 	/* Always get VRSAVE back */
-	if (__get_user(current->thread.vrsave, (u32 __user *)&sr->mc_vregs[32]))
-		return 1;
+	unsafe_get_user(current->thread.vrsave, (u32 __user *)&sr->mc_vregs[32], failed);
 	if (cpu_has_feature(CPU_FTR_ALTIVEC))
 		mtspr(SPRN_VRSAVE, current->thread.vrsave);
 #endif /* CONFIG_ALTIVEC */
-	if (copy_fpr_from_user(current, &sr->mc_fregs))
-		return 1;
+	unsafe_copy_fpr_from_user(current, &sr->mc_fregs, failed);
 
 #ifdef CONFIG_VSX
 	/*
@@ -548,8 +551,7 @@ static long restore_user_regs(struct pt_regs *regs,
 		 * Restore altivec registers from the stack to a local
 		 * buffer, then write this out to the thread_struct
 		 */
-		if (copy_vsx_from_user(current, &sr->mc_vsregs))
-			return 1;
+		unsafe_copy_vsx_from_user(current, &sr->mc_vsregs, failed);
 		current->thread.used_vsr = true;
 	} else if (current->thread.used_vsr)
 		for (i = 0; i < 32 ; i++)
@@ -567,19 +569,22 @@ static long restore_user_regs(struct pt_regs *regs,
 	regs->msr &= ~MSR_SPE;
 	if (msr & MSR_SPE) {
 		/* restore spe registers from the stack */
-		if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
-				     ELF_NEVRREG * sizeof(u32)))
-			return 1;
+		unsafe_copy_from_user(current->thread.evr, &sr->mc_vregs,
+				      ELF_NEVRREG * sizeof(u32));
 		current->thread.used_spe = true;
 	} else if (current->thread.used_spe)
 		memset(current->thread.evr, 0, ELF_NEVRREG * sizeof(u32));
 
 	/* Always get SPEFSCR back */
-	if (__get_user(current->thread.spefscr, (u32 __user *)&sr->mc_vregs + ELF_NEVRREG))
-		return 1;
+	unsafe_get_user(current->thread.spefscr, (u32 __user *)&sr->mc_vregs + ELF_NEVRREG, failed);
 #endif /* CONFIG_SPE */
 
+	user_read_access_end();
 	return 0;
+
+failed:
+	user_read_access_end();
+	return 1;
 }
 
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
@@ -592,7 +597,6 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 				 struct mcontext __user *sr,
 				 struct mcontext __user *tm_sr)
 {
-	long err;
 	unsigned long msr, msr_hi;
 #ifdef CONFIG_VSX
 	int i;
@@ -607,14 +611,13 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 	 * TFHAR is restored from the checkpointed NIP; TEXASR and TFIAR
 	 * were set by the signal delivery.
 	 */
-	err = restore_general_regs(&current->thread.ckpt_regs, sr);
-
-	err |= __get_user(current->thread.tm_tfhar, &sr->mc_gregs[PT_NIP]);
-
-	err |= __get_user(msr, &sr->mc_gregs[PT_MSR]);
-	if (err)
+	if (!user_read_access_begin(sr, sizeof(*sr)))
 		return 1;
 
+	unsafe_restore_general_regs(&current->thread.ckpt_regs, sr, failed);
+	unsafe_get_user(current->thread.tm_tfhar, &sr->mc_gregs[PT_NIP], failed);
+	unsafe_get_user(msr, &sr->mc_gregs[PT_MSR], failed);
+
 	/* Restore the previous little-endian mode */
 	regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
 
@@ -622,9 +625,8 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 	regs->msr &= ~MSR_VEC;
 	if (msr & MSR_VEC) {
 		/* restore altivec registers from the stack */
-		if (__copy_from_user(&current->thread.ckvr_state, &sr->mc_vregs,
-				     sizeof(sr->mc_vregs)))
-			return 1;
+		unsafe_copy_from_user(&current->thread.ckvr_state, &sr->mc_vregs,
+				      sizeof(sr->mc_vregs), failed);
 		current->thread.used_vr = true;
 	} else if (current->thread.used_vr) {
 		memset(&current->thread.vr_state, 0,
@@ -634,17 +636,15 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 	}
 
 	/* Always get VRSAVE back */
-	if (__get_user(current->thread.ckvrsave,
-		       (u32 __user *)&sr->mc_vregs[32]))
-		return 1;
+	unsafe_get_user(current->thread.ckvrsave,
+			(u32 __user *)&sr->mc_vregs[32], failed);
 	if (cpu_has_feature(CPU_FTR_ALTIVEC))
 		mtspr(SPRN_VRSAVE, current->thread.ckvrsave);
 #endif /* CONFIG_ALTIVEC */
 
 	regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1);
 
-	if (copy_fpr_from_user(current, &sr->mc_fregs))
-		return 1;
+	unsafe_copy_fpr_from_user(current, &sr->mc_fregs, failed);
 
 #ifdef CONFIG_VSX
 	regs->msr &= ~MSR_VSX;
@@ -653,8 +653,7 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 		 * Restore altivec registers from the stack to a local
 		 * buffer, then write this out to the thread_struct
 		 */
-		if (copy_ckvsx_from_user(current, &sr->mc_vsregs))
-			return 1;
+		unsafe_copy_ckvsx_from_user(current, &sr->mc_vsregs, failed);
 		current->thread.used_vsr = true;
 	} else if (current->thread.used_vsr)
 		for (i = 0; i < 32 ; i++) {
@@ -669,39 +668,36 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 	 */
 	regs->msr &= ~MSR_SPE;
 	if (msr & MSR_SPE) {
-		if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
-				     ELF_NEVRREG * sizeof(u32)))
-			return 1;
+		unsafe_copy_from_user(current->thread.evr, &sr->mc_vregs,
+				      ELF_NEVRREG * sizeof(u32), failed);
 		current->thread.used_spe = true;
 	} else if (current->thread.used_spe)
 		memset(current->thread.evr, 0, ELF_NEVRREG * sizeof(u32));
 
 	/* Always get SPEFSCR back */
-	if (__get_user(current->thread.spefscr, (u32 __user *)&sr->mc_vregs
-		       + ELF_NEVRREG))
-		return 1;
+	unsafe_get_user(current->thread.spefscr,
+			(u32 __user *)&sr->mc_vregs + ELF_NEVRREG, failed);
 #endif /* CONFIG_SPE */
 
-	err = restore_general_regs(regs, tm_sr);
-	if (err)
+	user_read_access_end();
+
+	if (!user_read_access_begin(tm_sr, sizeof(*tm_sr)))
 		return 1;
 
+	unsafe_restore_general_regs(regs, tm_sr, failed);
+
 #ifdef CONFIG_ALTIVEC
 	/* restore altivec registers from the stack */
 	if (msr & MSR_VEC)
-		if (__copy_from_user(&current->thread.vr_state,
-				     &tm_sr->mc_vregs,
-				     sizeof(sr->mc_vregs)))
-			return 1;
+		unsafe_copy_from_user(&current->thread.vr_state, &tm_sr->mc_vregs,
+				      sizeof(sr->mc_vregs), failed);
 
 	/* Always get VRSAVE back */
-	if (__get_user(current->thread.vrsave,
-		       (u32 __user *)&tm_sr->mc_vregs[32]))
-		return 1;
+	unsafe_get_user(current->thread.vrsave,
+			(u32 __user *)&tm_sr->mc_vregs[32], failed);
 #endif /* CONFIG_ALTIVEC */
 
-	if (copy_ckfpr_from_user(current, &tm_sr->mc_fregs))
-		return 1;
+	unsafe_copy_ckfpr_from_user(current, &tm_sr->mc_fregs, failed);
 
 #ifdef CONFIG_VSX
 	if (msr & MSR_VSX) {
@@ -709,16 +705,17 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 		 * Restore altivec registers from the stack to a local
 		 * buffer, then write this out to the thread_struct
 		 */
-		if (copy_vsx_from_user(current, &tm_sr->mc_vsregs))
-			return 1;
+		unsafe_copy_vsx_from_user(current, &tm_sr->mc_vsregs, failed);
 		current->thread.used_vsr = true;
 	}
 #endif /* CONFIG_VSX */
 
 	/* Get the top half of the MSR from the user context */
-	if (__get_user(msr_hi, &tm_sr->mc_gregs[PT_MSR]))
-		return 1;
+	unsafe_get_user(msr_hi, &tm_sr->mc_gregs[PT_MSR], failed);
 	msr_hi <<= 32;
+
+	user_read_access_end();
+
 	/* If TM bits are set to the reserved value, it's an invalid context */
 	if (MSR_TM_RESV(msr_hi))
 		return 1;
@@ -766,6 +763,10 @@ static long restore_tm_user_regs(struct pt_regs *regs,
 	preempt_enable();
 
 	return 0;
+
+failed:
+	user_read_access_end();
+	return 1;
 }
 #else
 static long restore_tm_user_regs(struct pt_regs *regs, struct mcontext __user *sr,