um: Set __HAVE_ARCH_GATE_AREA for i386

When UML is unable to reuse the host's vDSO FIXADDR_USER_START is zero. To handle this special case correclty we have to implement custom gate area helper methods. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

um: Set __HAVE_ARCH_GATE_AREA for i386
When UML is unable to reuse the host's vDSO FIXADDR_USER_START is zero. To handle this special case correclty we have to implement custom gate area helper methods. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Richard Weinberger · Linus Torvalds
1 parent b743ac54e5
Showing 3 changed files with 65 additions and 1 deletions Side-by-side Diff
arch/um/sys-i386/Makefile
arch/um/sys-i386/asm/elf.h
arch/um/sys-i386/mem.c
@@ -4,7 +4,7 @@
  
 obj-y = bug.o bugs.o checksum.o delay.o fault.o ksyms.o ldt.o ptrace.o \
 	ptrace_user.o setjmp.o signal.o stub.o stub_segv.o syscalls.o sysrq.o \
-	sys_call_table.o tls.o atomic64_cx8_32.o
+	sys_call_table.o tls.o atomic64_cx8_32.o mem.o
  
 obj-$(CONFIG_BINFMT_ELF) += elfcore.o
  
@@ -105,6 +105,8 @@
 #define FIXADDR_USER_START      VSYSCALL_BASE
 #define FIXADDR_USER_END        VSYSCALL_END
  
+#define __HAVE_ARCH_GATE_AREA 1
+
 /*
  * Architecture-neutral AT_ values in 0-17, leave some room
  * for more of them, start the x86-specific ones at 32.
+/*
+ * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/mm.h>
+#include <asm/page.h>
+#include <asm/mman.h>
+
+static struct vm_area_struct gate_vma;
+
+static int __init gate_vma_init(void)
+{
+	if (!FIXADDR_USER_START)
+		return 0;
+
+	gate_vma.vm_mm = NULL;
+	gate_vma.vm_start = FIXADDR_USER_START;
+	gate_vma.vm_end = FIXADDR_USER_END;
+	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
+	gate_vma.vm_page_prot = __P101;
+
+	/*
+	 * Make sure the vDSO gets into every core dump.
+	 * Dumping its contents makes post-mortem fully interpretable later
+	 * without matching up the same kernel and hardware config to see
+	 * what PC values meant.
+	 */
+	gate_vma.vm_flags |= VM_ALWAYSDUMP;
+
+	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);
+}
...	...	@@ -4,7 +4,7 @@
4	4
5	5	obj-y = bug.o bugs.o checksum.o delay.o fault.o ksyms.o ldt.o ptrace.o \
6	6	ptrace_user.o setjmp.o signal.o stub.o stub_segv.o syscalls.o sysrq.o \
7		- sys_call_table.o tls.o atomic64_cx8_32.o
	7	+ sys_call_table.o tls.o atomic64_cx8_32.o mem.o
8	8
9	9	obj-$(CONFIG_BINFMT_ELF) += elfcore.o
10	10
...	...	@@ -105,6 +105,8 @@
105	105	#define FIXADDR_USER_START VSYSCALL_BASE
106	106	#define FIXADDR_USER_END VSYSCALL_END
107	107
	108	+#define __HAVE_ARCH_GATE_AREA 1
	109	+
108	110	/*
109	111	* Architecture-neutral AT_ values in 0-17, leave some room
110	112	* for more of them, start the x86-specific ones at 32.
	1	+/*
	2	+ * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
	3	+ *
	4	+ * This program is free software; you can redistribute it and/or modify
	5	+ * it under the terms of the GNU General Public License version 2 as
	6	+ * published by the Free Software Foundation.
	7	+ */
	8	+
	9	+#include <linux/mm.h>
	10	+#include <asm/page.h>
	11	+#include <asm/mman.h>
	12	+
	13	+static struct vm_area_struct gate_vma;
	14	+
	15	+static int __init gate_vma_init(void)
	16	+{
	17	+ if (!FIXADDR_USER_START)
	18	+ return 0;
	19	+
	20	+ gate_vma.vm_mm = NULL;
	21	+ gate_vma.vm_start = FIXADDR_USER_START;
	22	+ gate_vma.vm_end = FIXADDR_USER_END;
	23	+ gate_vma.vm_flags = VM_READ \| VM_MAYREAD \| VM_EXEC \| VM_MAYEXEC;
	24	+ gate_vma.vm_page_prot = __P101;
	25	+
	26	+ /*
	27	+ * Make sure the vDSO gets into every core dump.
	28	+ * Dumping its contents makes post-mortem fully interpretable later
	29	+ * without matching up the same kernel and hardware config to see
	30	+ * what PC values meant.
	31	+ */
	32	+ gate_vma.vm_flags \|= VM_ALWAYSDUMP;
	33	+
	34	+ return 0;
	35	+}
	36	+__initcall(gate_vma_init);
	37	+
	38	+struct vm_area_struct get_gate_vma(struct mm_struct mm)
	39	+{
	40	+ return FIXADDR_USER_START ? &gate_vma : NULL;
	41	+}
	42	+
	43	+int in_gate_area_no_mm(unsigned long addr)
	44	+{
	45	+ if (!FIXADDR_USER_START)
	46	+ return 0;
	47	+
	48	+ if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
	49	+ return 1;
	50	+
	51	+ return 0;
	52	+}
	53	+
	54	+int in_gate_area(struct mm_struct *mm, unsigned long addr)
	55	+{
	56	+ struct vm_area_struct *vma = get_gate_vma(mm);
	57	+
	58	+ if (!vma)
	59	+ return 0;
	60	+
	61	+ return (addr >= vma->vm_start) && (addr < vma->vm_end);
	62	+}