Received-SPF: pass (google.com: domain of linux-kernel+bounces-100482-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Date: Tue, 12 Mar 2024 15:56:41 +0000
In-Reply-To: <20240312155641.4003683-1-yosryahmed@google.com>
Precedence: bulk
Mime-Version: 1.0
References: <20240312155641.4003683-1-yosryahmed@google.com>
Message-ID: <20240312155641.4003683-3-yosryahmed@google.com>
Subject: [PATCH v2 3/3] x86/mm: Cleanup prctl_enable_tagged_addr() nr_bits
 error checking
From: Yosry Ahmed <yosryahmed@google.com>
To: x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, 
	Dave Hansen <dave.hansen@linux.intel.com>, "H. Peter Anvin" <hpa@zytor.com>, 
	Andy Lutomirski <luto@kernel.org>, Peter Zijlstra <peterz@infradead.org>, 
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, 
	Rick Edgecombe <rick.p.edgecombe@intel.com>, Andrew Morton <akpm@linux-foundation.org>, 
	linux-mm@kvack.org, linux-kernel@vger.kernel.org, 
	Yosry Ahmed <yosryahmed@google.com>
Content-Type: text/plain; charset="UTF-8"

There are two separate checks in prctl_enable_tagged_addr() that nr_bits
is in the correct range. The checks are arranged such the correct case
is sandwiched between both error cases, which do exactly the same thing.

Simplify the if condition and pull the correct case outside with the
rest of the success code path.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/x86/kernel/process_64.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 3dd8c1f51e45c..8349431136530 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -783,17 +783,13 @@ static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits)
 		return -EBUSY;
 	}
 
-	if (!nr_bits) {
-		mmap_write_unlock(mm);
-		return -EINVAL;
-	} else if (nr_bits <= LAM_U57_BITS) {
-		mm->context.lam_cr3_mask = X86_CR3_LAM_U57;
-		mm->context.untag_mask =  ~GENMASK(62, 57);
-	} else {
+	if (!nr_bits || nr_bits > LAM_U57_BITS) {
 		mmap_write_unlock(mm);
 		return -EINVAL;
 	}
 
+	mm->context.lam_cr3_mask = X86_CR3_LAM_U57;
+	mm->context.untag_mask =  ~GENMASK(62, 57);
 	on_each_cpu_mask(mm_cpumask(mm), enable_lam_func, mm, true);
 	set_bit(MM_CONTEXT_LOCK_LAM, &mm->context.flags);
 
-- 
2.44.0.278.ge034bb2e1d-goog