shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-05 02:21:52 +09:00
Code Issues Packages Projects Releases Wiki Activity

mm: add generic function_nocfi macro

Browse Source 
With CONFIG_CFI_CLANG, the compiler replaces function addresses
in instrumented C code with jump table addresses. This means that
__pa_symbol(function) returns the physical address of the jump table
entry instead of the actual function, which may not work as the jump
table code will immediately jump to a virtual address that may not be
mapped.

To avoid this address space confusion, this change adds a generic
definition for function_nocfi(), which architectures that support CFI
can override. The typical implementation of would use inline assembly
to take the function address, which avoids compiler instrumentation.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-4-samitolvanen@google.com
This commit is contained in:
Sami Tolvanen
2021-04-08 11:28:28 -07:00
committed by Kees Cook
parent ff301ceb52
commit 5caf968262
1 changed files with 10 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
include/linux/mm.h
View File

@@ -124,6 +124,16 @@ extern int mmap_rnd_compat_bits __read_mostly;
#define lm_alias(x) __va(__pa_symbol(x))
#endif
/*
* With CONFIG_CFI_CLANG, the compiler replaces function addresses in
* instrumented C code with jump table addresses. Architectures that
* support CFI can define this macro to return the actual function address
* when needed.
*/
#ifndef function_nocfi
#define function_nocfi(x) (x)
#endif
/*
* To prevent common memory management code establishing
* a zero page mapping on a read fault.