linux-kernel - [RESEND PATCH v3 3/3] x86/mm: Cleanup prctl_enable_tagged_addr() nr

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Date: Tue,  2 Jul 2024 13:21:39 +0000
From: Yosry Ahmed <yosryahmed@...gle.com>
To: x86@...nel.org
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, 
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	Yosry Ahmed <yosryahmed@...gle.com>
Subject: [RESEND PATCH v3 3/3] x86/mm: Cleanup prctl_enable_tagged_addr()
 nr_bits error checking

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.

Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Change-Id: Ia4f78de99d02f8ce28787346404d59ef13ca3d92
Signed-off-by: Yosry Ahmed <yosryahmed@...gle.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 26a853328f2d4..c62098332f05c 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -831,17 +831,13 @@ 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);
 
-- 
2.45.2.803.g4e1b14247a-goog