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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: [PATCH 5.4 67/96] arm64: ptrace: nofpsimd: Fail FP/SIMD regset operations
Date:   Thu, 13 Feb 2020 07:21:14 -0800
Message-Id: <20200213151904.616191583@linuxfoundation.org>
In-Reply-To: <20200213151839.156309910@linuxfoundation.org>
References: <20200213151839.156309910@linuxfoundation.org>
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From: Suzuki K Poulose <suzuki.poulose@arm.com>

commit c9d66999f064947e6b577ceacc1eb2fbca6a8d3c upstream.

When fp/simd is not supported on the system, fail the operations
of FP/SIMD regsets.

Fixes: 82e0191a1aa11abf ("arm64: Support systems without FP/ASIMD")
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/ptrace.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -615,6 +615,13 @@ static int gpr_set(struct task_struct *t
 	return 0;
 }
 
+static int fpr_active(struct task_struct *target, const struct user_regset *regset)
+{
+	if (!system_supports_fpsimd())
+		return -ENODEV;
+	return regset->n;
+}
+
 /*
  * TODO: update fp accessors for lazy context switching (sync/flush hwstate)
  */
@@ -637,6 +644,9 @@ static int fpr_get(struct task_struct *t
 		   unsigned int pos, unsigned int count,
 		   void *kbuf, void __user *ubuf)
 {
+	if (!system_supports_fpsimd())
+		return -EINVAL;
+
 	if (target == current)
 		fpsimd_preserve_current_state();
 
@@ -676,6 +686,9 @@ static int fpr_set(struct task_struct *t
 {
 	int ret;
 
+	if (!system_supports_fpsimd())
+		return -EINVAL;
+
 	ret = __fpr_set(target, regset, pos, count, kbuf, ubuf, 0);
 	if (ret)
 		return ret;
@@ -1134,6 +1147,7 @@ static const struct user_regset aarch64_
 		 */
 		.size = sizeof(u32),
 		.align = sizeof(u32),
+		.active = fpr_active,
 		.get = fpr_get,
 		.set = fpr_set
 	},
@@ -1348,6 +1362,9 @@ static int compat_vfp_get(struct task_st
 	compat_ulong_t fpscr;
 	int ret, vregs_end_pos;
 
+	if (!system_supports_fpsimd())
+		return -EINVAL;
+
 	uregs = &target->thread.uw.fpsimd_state;
 
 	if (target == current)
@@ -1381,6 +1398,9 @@ static int compat_vfp_set(struct task_st
 	compat_ulong_t fpscr;
 	int ret, vregs_end_pos;
 
+	if (!system_supports_fpsimd())
+		return -EINVAL;
+
 	uregs = &target->thread.uw.fpsimd_state;
 
 	vregs_end_pos = VFP_STATE_SIZE - sizeof(compat_ulong_t);
@@ -1438,6 +1458,7 @@ static const struct user_regset aarch32_
 		.n = VFP_STATE_SIZE / sizeof(compat_ulong_t),
 		.size = sizeof(compat_ulong_t),
 		.align = sizeof(compat_ulong_t),
+		.active = fpr_active,
 		.get = compat_vfp_get,
 		.set = compat_vfp_set
 	},