Commit a3cb7a03 authored Sep 10, 2020 by Sami Tolvanen

ANDROID: mm: add generic __va_function and __pa_function



We use non-canonical CFI jump tables with CONFIG_CFI_CLANG, which
means the compiler replaces function address references with the
address of the function's CFI jump table entry. This results in
__pa_symbol(function), for example, returning the physical address
of the jump table entry, which can lead to address space confusion
since the jump table itself points to a virtual address.

This change adds generic definitions for __pa/va_function, which
architectures that support CFI can override.

Bug: 166220312
Change-Id: If4a162de7854547d8437bf59be03eb6d16220832
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

parent 802f3427

include/linux/mm.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -116,6 +116,14 @@ extern int mmap_rnd_compat_bits __read_mostly;
		#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0))
		#endif

		#ifndef __va_function
		#define __va_function(x) (x)
		#endif

		#ifndef __pa_function
		#define __pa_function(x) __pa_symbol(x)
		#endif

		#ifndef page_to_virt
		#define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x)))
		#endif