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ANDROID: x86: map CFI jump tables in pti_clone_entry_text

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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: 145210207
Change-Id: I4ad3506f7a365cd068009348d45b54e228e42e33
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Sami Tolvanen
2020-01-09 13:11:05 -08:00
committed by Alistair Delva
parent cdf744be2b
commit 13f7806690
3 changed files with 14 additions and 0 deletions
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1
arch/x86/include/asm/sections.h
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@@ -8,6 +8,7 @@
#include <asm/extable.h> #include <asm/extable.h>
extern char __brk_base[], __brk_limit[]; extern char __brk_base[], __brk_limit[];
extern char __cfi_jt_start[], __cfi_jt_end[];
extern char __end_rodata_aligned[]; extern char __end_rodata_aligned[];
#if defined(CONFIG_X86_64) #if defined(CONFIG_X86_64)

4
arch/x86/kernel/vmlinux.lds.S
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@@ -490,3 +490,7 @@ INIT_PER_CPU(irq_stack_backing_store);
"kexec control code size is too big"); "kexec control code size is too big");
#endif #endif
#ifdef CONFIG_CFI_CLANG
. = ASSERT((__cfi_jt_end - __cfi_jt_start > 0),
"CFI jump table is empty");
#endif

9
arch/x86/mm/pti.c
View File

@@ -498,6 +498,15 @@ static void pti_clone_entry_text(void)
pti_clone_pgtable((unsigned long) __entry_text_start, pti_clone_pgtable((unsigned long) __entry_text_start,
(unsigned long) __entry_text_end, (unsigned long) __entry_text_end,
PTI_CLONE_PMD); 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);
} }
/* /*