Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d223246e authored by Anders Kaseorg's avatar Anders Kaseorg Committed by H. Peter Anvin
Browse files

x86: fix fragile computation of vsyscall address 



Previously, the address of the vsyscall page (VSYSCALL_PHYS_ADDR,
VSYSCALL_VIRT_ADDR) was computed by arithmetic on the address of the
last section.  This leads to bugs when new sections are inserted, such
as the one fixed by commit d312ceda.
Let's compute it from the current address instead.

Signed-off-by: default avatarAnders Kaseorg <andersk@ksplice.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent daf7b9c9

arch/x86/kernel/vmlinux.lds.S

+7 −12
Original line number Diff line number Diff line
@@ -135,24 +135,21 @@ SECTIONS 
#ifdef CONFIG_X86_64



#define VSYSCALL_ADDR (-10*1024*1024)

#define VSYSCALL_PHYS_ADDR ((LOADADDR(.data) + SIZEOF(.data) + \

                            PAGE_SIZE - 1) & ~(PAGE_SIZE - 1))

#define VSYSCALL_VIRT_ADDR ((ADDR(.data) + SIZEOF(.data) + \

                            PAGE_SIZE - 1) & ~(PAGE_SIZE - 1))



#define VLOAD_OFFSET (VSYSCALL_ADDR - VSYSCALL_PHYS_ADDR)

#define VLOAD_OFFSET (VSYSCALL_ADDR - __vsyscall_0 + LOAD_OFFSET)

#define VLOAD(x) (ADDR(x) - VLOAD_OFFSET)



#define VVIRT_OFFSET (VSYSCALL_ADDR - VSYSCALL_VIRT_ADDR)

#define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0)

#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)



	. = ALIGN(4096);

	__vsyscall_0 = .;



	. = VSYSCALL_ADDR;

	.vsyscall_0 : AT(VSYSCALL_PHYS_ADDR) {

	.vsyscall_0 : AT(VLOAD(.vsyscall_0)) {

		*(.vsyscall_0)

	} :user



	__vsyscall_0 = VSYSCALL_VIRT_ADDR;



	. = ALIGN(CONFIG_X86_L1_CACHE_BYTES);

	.vsyscall_fn : AT(VLOAD(.vsyscall_fn)) {

		*(.vsyscall_fn)
@@ -192,11 +189,9 @@ SECTIONS 
		*(.vsyscall_3)

	}



	. = VSYSCALL_VIRT_ADDR + PAGE_SIZE;

	. = __vsyscall_0 + PAGE_SIZE;



#undef VSYSCALL_ADDR

#undef VSYSCALL_PHYS_ADDR

#undef VSYSCALL_VIRT_ADDR

#undef VLOAD_OFFSET

#undef VLOAD

#undef VVIRT_OFFSET