linux-kernel - [PATCH 05/10] x86/um: Drop gate area handling

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Message-Id: <20251028-uml-remove-32bit-pseudo-vdso-v1-5-e930063eff5f@weissschuh.net>
Date: Tue, 28 Oct 2025 10:15:40 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Richard Weinberger <richard@....at>, 
 Anton Ivanov <anton.ivanov@...bridgegreys.com>, 
 Johannes Berg <johannes@...solutions.net>, 
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
 x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
 Kees Cook <kees@...nel.org>
Cc: linux-um@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 linux-mm@...ck.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH 05/10] x86/um: Drop gate area handling

With the removal of the vDSO passthrough from the host,
FIXADDR_USER_START is always 0 and the gate area setup code is dead.

Remove it.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 arch/um/include/asm/page.h |  4 ----
 arch/x86/um/Makefile       |  4 ++--
 arch/x86/um/mem_32.c       | 50 ----------------------------------------------
 3 files changed, 2 insertions(+), 56 deletions(-)

diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
index 6f54254aaf44..2d363460d896 100644
--- a/arch/um/include/asm/page.h
+++ b/arch/um/include/asm/page.h
@@ -96,8 +96,4 @@ extern unsigned long uml_physmem;
 
 #endif	/* __ASSEMBLER__ */
 
-#ifdef CONFIG_X86_32
-#define __HAVE_ARCH_GATE_AREA 1
-#endif
-
 #endif	/* __UM_PAGE_H */
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index 1767e6061b4d..f9ea75bf43ac 100644
--- a/arch/x86/um/Makefile
+++ b/arch/x86/um/Makefile
@@ -13,7 +13,7 @@ obj-y = bugs_$(BITS).o delay.o fault.o \
 	ptrace.o ptrace_$(BITS).o ptrace_user.o setjmp_$(BITS).o signal.o \
 	stub_segv.o \
 	sys_call_table_$(BITS).o sysrq_$(BITS).o tls_$(BITS).o \
-	mem_$(BITS).o subarch.o os-Linux/
+	subarch.o os-Linux/
 
 ifeq ($(CONFIG_X86_32),y)
 
@@ -26,7 +26,7 @@ subarch-y += ../kernel/sys_ia32.o
 
 else
 
-obj-y += syscalls_64.o vdso/
+obj-y += mem_64.o syscalls_64.o vdso/
 
 subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o \
 	../lib/memmove_64.o ../lib/memset_64.o
diff --git a/arch/x86/um/mem_32.c b/arch/x86/um/mem_32.c
deleted file mode 100644
index 29b2203bc82c..000000000000
--- a/arch/x86/um/mem_32.c
+++ /dev/null
@@ -1,50 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (C) 2011 Richard Weinberger <richrd@....at>
- */
-
-#include <linux/mm.h>
-#include <asm/elf.h>
-
-static struct vm_area_struct gate_vma;
-
-static int __init gate_vma_init(void)
-{
-	if (!FIXADDR_USER_START)
-		return 0;
-
-	vma_init(&gate_vma, NULL);
-	gate_vma.vm_start = FIXADDR_USER_START;
-	gate_vma.vm_end = FIXADDR_USER_END;
-	vm_flags_init(&gate_vma, VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC);
-	gate_vma.vm_page_prot = PAGE_READONLY;
-
-	return 0;
-}
-__initcall(gate_vma_init);
-
-struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
-{
-	return FIXADDR_USER_START ? &gate_vma : NULL;
-}
-
-int in_gate_area_no_mm(unsigned long addr)
-{
-	if (!FIXADDR_USER_START)
-		return 0;
-
-	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
-		return 1;
-
-	return 0;
-}
-
-int in_gate_area(struct mm_struct *mm, unsigned long addr)
-{
-	struct vm_area_struct *vma = get_gate_vma(mm);
-
-	if (!vma)
-		return 0;
-
-	return (addr >= vma->vm_start) && (addr < vma->vm_end);
-}

-- 
2.51.1.dirty