Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 17658ae1 authored by Will Deacon's avatar Will Deacon Committed by Gerrit - the friendly Code Review server
Browse files

FROMLIST: arm64: kaslr: Put kernel vectors address in separate data page 



The literal pool entry for identifying the vectors base is the only piece
of information in the trampoline page that identifies the true location
of the kernel.

This patch moves it into a page-aligned region of the .rodata section
and maps this adjacent to the trampoline text via an additional fixmap
entry, which protects against any accidental leakage of the trampoline
contents.

Suggested-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: default avatarLaura Abbott <labbott@redhat.com>
Tested-by: default avatarShanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
(cherry picked from git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git


 commit 6c27c4082f4f70b9f41df4d0adf51128b40351df)
[ghackmann@google.com:
 - adjust context
 - replace ARM64_WORKAROUND_QCOM_FALKOR_E1003 alternative with
   compile-time CONFIG_ARCH_MSM8996 check]
Signed-off-by: default avatarGreg Hackmann <ghackmann@google.com>
Change-Id: Id96c1b0eaca8d2ff2e91320ac13d76b18d05fdd5
Git-Commit: 90523e83
Git-repo: git://android.googlesource.com/kernel/common.git


Signed-off-by: default avatarVinayak Menon <vinmenon@codeaurora.org>
parent cf4324bb

arch/arm64/include/asm/fixmap.h

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ enum fixed_addresses { 
	FIX_HOLE,

	FIX_EARLYCON_MEM_BASE,

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0

	FIX_ENTRY_TRAMP_DATA,

	FIX_ENTRY_TRAMP_TEXT,

#define TRAMP_VALIAS		(__fix_to_virt(FIX_ENTRY_TRAMP_TEXT))

#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */

arch/arm64/kernel/entry.S

+16 −0
Original line number Diff line number Diff line
@@ -936,7 +936,15 @@ __ni_sys_trace: 
	msr	tpidrro_el0, x30	// Restored in kernel_ventry

	.endif

	tramp_map_kernel	x30

#ifdef CONFIG_RANDOMIZE_BASE

	adr	x30, tramp_vectors + PAGE_SIZE

#ifndef CONFIG_ARCH_MSM8996

	isb

#endif

	ldr	x30, [x30]

#else

	ldr	x30, =vectors

#endif

	prfm	plil1strm, [x30, #(1b - tramp_vectors)]

	msr	vbar_el1, x30

	add	x30, x30, #(1b - tramp_vectors)
@@ -979,6 +987,14 @@ END(tramp_exit_compat) 


	.ltorg

	.popsection				// .entry.tramp.text

#ifdef CONFIG_RANDOMIZE_BASE

	.pushsection ".rodata", "a"

	.align PAGE_SHIFT

	.globl	__entry_tramp_data_start

__entry_tramp_data_start:

	.quad	vectors

	.popsection				// .rodata

#endif /* CONFIG_RANDOMIZE_BASE */

#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */



/*

arch/arm64/kernel/vmlinux.lds.S

+4 −0
Original line number Diff line number Diff line
@@ -197,6 +197,10 @@ SECTIONS 
ASSERT(((__hyp_idmap_text_start + PAGE_SIZE) > __hyp_idmap_text_end),

       "HYP init code too big")



#ifdef CONFIG_UNMAP_KERNEL_AT_EL0

ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE,

	"Entry trampoline text too big")

#endif

/*

 * If padding is applied before .head.text, virt<->phys conversions will fail.

 */

arch/arm64/mm/mmu.c

+9 −1
Original line number Diff line number Diff line
@@ -700,8 +700,16 @@ static int __init map_entry_trampoline(void) 
	__create_mapping(NULL, tramp_pg_dir + pgd_index(TRAMP_VALIAS), pa_start,

		TRAMP_VALIAS, PAGE_SIZE, prot, pgd_pgtable_alloc, false);



	/* ...as well as the kernel page table */

	/* Map both the text and data into the kernel page table */

	__set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);

	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {

		extern char __entry_tramp_data_start[];



		__set_fixmap(FIX_ENTRY_TRAMP_DATA,

			     __pa_symbol(__entry_tramp_data_start),

			     PAGE_KERNEL_RO);

	}



	return 0;

}

core_initcall(map_entry_trampoline);