[PATCH 07/10] x86: make TASK_SIZE_MAX usable from assembly code

Christoph Hellwig
2020-08-27T15:04:09Z

For 64-bit the only thing missing was a strategic _AC, and for 32-bit we
need to use __PAGE_OFFSET instead of PAGE_OFFSET in the TASK_SIZE
definition to escape the explicit unsigned long cast. This just works
because __PAGE_OFFSET is defined using _AC itself and thus never needs
the cast anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
arch/x86/include/asm/page_32_types.h | 4 ++--
arch/x86/include/asm/page_64_types.h | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/page_32_types.h b/arch/x86/include/asm/page_32_types.h
index 26236925fb2c36..f462895a33e452 100644
--- a/arch/x86/include/asm/page_32_types.h
+++ b/arch/x86/include/asm/page_32_types.h
@@ -44,8 +44,8 @@
/*
* User space process size: 3GB (default).
*/
-#define IA32_PAGE_OFFSET PAGE_OFFSET
-#define TASK_SIZE PAGE_OFFSET
+#define IA32_PAGE_OFFSET __PAGE_OFFSET
+#define TASK_SIZE __PAGE_OFFSET
#define TASK_SIZE_LOW TASK_SIZE
#define TASK_SIZE_MAX TASK_SIZE
#define DEFAULT_MAP_WINDOW TASK_SIZE
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 996595c9897e0a..838515daf87b36 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -76,7 +76,7 @@
*
* With page table isolation enabled, we map the LDT in ... [stay tuned]
*/
-#define TASK_SIZE_MAX ((1UL << __VIRTUAL_MASK_SHIFT) - PAGE_SIZE)
+#define TASK_SIZE_MAX ((_AC(1,UL) << __VIRTUAL_MASK_SHIFT) - PAGE_SIZE)

#define DEFAULT_MAP_WINDOW ((1UL << 47) - PAGE_SIZE)

--
2.28.0