From: Dave Hansen <[email protected]>
The x86 code has several places where it frees parts of kernel image: 1. Unused SMP alternative 2. __init code 3. The hole between text and rodata 4. The hole between rodata and data We call free_init_pages() to do this. Strangely, we convert the symbol addresses to kernel direct map addresses in some cases (#3, #4) but not others (#1, #2). The virt_to_page() and the other code in free_reserved_area() now works fine for for symbol addresses on x86, so don't bother converting the addresses to direct map addresses before freeing them. Signed-off-by: Dave Hansen <[email protected]> Cc: Kees Cook <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Andi Kleen <[email protected]> --- b/arch/x86/mm/init_64.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff -puN arch/x86/mm/init_64.c~x86-init-do-not-convert-symbol-addresses arch/x86/mm/init_64.c --- a/arch/x86/mm/init_64.c~x86-init-do-not-convert-symbol-addresses 2018-08-02 14:14:48.380483277 -0700 +++ b/arch/x86/mm/init_64.c 2018-08-02 14:14:48.383483277 -0700 @@ -1283,12 +1283,8 @@ void mark_rodata_ro(void) set_memory_ro(start, (end-start) >> PAGE_SHIFT); #endif - free_init_pages("unused kernel", - (unsigned long) __va(__pa_symbol(text_end)), - (unsigned long) __va(__pa_symbol(rodata_start))); - free_init_pages("unused kernel", - (unsigned long) __va(__pa_symbol(rodata_end)), - (unsigned long) __va(__pa_symbol(_sdata))); + free_init_pages("unused kernel", text_end, rodata_start); + free_init_pages("unused kernel", rodata_end, _sdata); debug_checkwx(); _
