[PATCH] powerpc/vdso: Don't map VDSO at a fixed address on PPC32
From: Christophe Leroy <hidden>
Date: 2022-08-18 17:31:58
PPC64 removed default mapping address from VDSO in
commit 30d0b3682887 ("powerpc: Move 64bit VDSO to improve context
switch performance").
Do like PPC64 and let get_unmapped_area() place the VDSO mapping
at the address it wants, don't force a default address.
This allows randomisation of VDSO address.
Signed-off-by: Christophe Leroy <redacted>
---
arch/powerpc/include/asm/vdso.h | 3 ---
arch/powerpc/kernel/vdso.c | 13 ++-----------
2 files changed, 2 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/include/asm/vdso.h b/arch/powerpc/include/asm/vdso.h
index 8542e9bbeead..7650b6ce14c8 100644
--- a/arch/powerpc/include/asm/vdso.h
+++ b/arch/powerpc/include/asm/vdso.h@@ -2,9 +2,6 @@ #ifndef _ASM_POWERPC_VDSO_H #define _ASM_POWERPC_VDSO_H -/* Default map addresses for 32bit vDSO */ -#define VDSO32_MBASE 0x100000 - #define VDSO_VERSION_STRING LINUX_2.6.15 #ifndef __ASSEMBLY__
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 0da287544054..bf9574ec26ce 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c@@ -200,28 +200,19 @@ static int __arch_setup_additional_pages(struct linux_binprm *bprm, int uses_int if (is_32bit_task()) { vdso_spec = &vdso32_spec; vdso_size = &vdso32_end - &vdso32_start; - vdso_base = VDSO32_MBASE; } else { vdso_spec = &vdso64_spec; vdso_size = &vdso64_end - &vdso64_start; - /* - * On 64bit we don't have a preferred map address. This - * allows get_unmapped_area to find an area near other mmaps - * and most likely share a SLB entry. - */ - vdso_base = 0; } mappings_size = vdso_size + vvar_size; mappings_size += (VDSO_ALIGNMENT - 1) & PAGE_MASK; /* - * pick a base address for the vDSO in process space. We try to put it - * at vdso_base which is the "natural" base for it, but we might fail - * and end up putting it elsewhere. + * Pick a base address for the vDSO in process space. * Add enough to the size so that the result can be aligned. */ - vdso_base = get_unmapped_area(NULL, vdso_base, mappings_size, 0, 0); + vdso_base = get_unmapped_area(NULL, 0, mappings_size, 0, 0); if (IS_ERR_VALUE(vdso_base)) return vdso_base;
--
2.37.1