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Commit 88f78b7e authored by Sami Tolvanen's avatar Sami Tolvanen
Browse files

ANDROID: x86: map CFI jump tables in pti_clone_entry_text 



Allow CFI enabled entry code to make indirect calls by also mapping
CFI jump tables, and add a check to ensure the jump table section is
not empty.

Bug: 145297900
Change-Id: I1204c50a139ba62234f3bb4699c50921a831162b
Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
parent 9c7e3869

arch/x86/include/asm/sections.h

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <asm/extable.h>



extern char __brk_base[], __brk_limit[];

extern char __cfi_jt_start[], __cfi_jt_end[];

extern char __end_rodata_aligned[];



#if defined(CONFIG_X86_64)

arch/x86/kernel/vmlinux.lds.S

+11 −0
Original line number Diff line number Diff line
@@ -141,6 +141,13 @@ SECTIONS 
		*(.text.__x86.indirect_thunk)

		__indirect_thunk_end = .;

#endif



#ifdef CONFIG_CFI_CLANG

		. = ALIGN(PAGE_SIZE);

		__cfi_jt_start = .;

		*(.text..L.cfi.jumptable .text..L.cfi.jumptable.*)

		__cfi_jt_end = .;

#endif

	} :text = 0x9090



	NOTES :text :note
@@ -457,3 +464,7 @@ INIT_PER_CPU(irq_stack_backing_store); 
           "kexec control code size is too big");

#endif



#ifdef CONFIG_CFI_CLANG

. = ASSERT((__cfi_jt_end - __cfi_jt_start > 0),

	   "CFI jump table is empty");

#endif

arch/x86/mm/pti.c

+9 −0
Original line number Diff line number Diff line
@@ -505,6 +505,15 @@ static void pti_clone_entry_text(void) 
	pti_clone_pgtable((unsigned long) __entry_text_start,

			  (unsigned long) __irqentry_text_end,

			  PTI_CLONE_PMD);



	/*

	 * If CFI is enabled, also map jump tables, so the entry code can

	 * make indirect calls.

	 */

	if (IS_ENABLED(CONFIG_CFI_CLANG))

		pti_clone_pgtable((unsigned long) __cfi_jt_start,

				  (unsigned long) __cfi_jt_end,

				  PTI_CLONE_PMD);

}



/*