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Commit 99a21300 authored by James Morse's avatar James Morse Committed by Gerrit - the friendly Code Review server
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arm64: entry: Add macro for reading symbol addresses from the trampoline 



commit b28a8eebe81c186fdb1a0078263b30576c8e1f42 upstream.

The trampoline code needs to use the address of symbols in the wider
kernel, e.g., vectors. PC-relative addressing wouldn't work as the
trampoline code doesn't run at the address the linker expected.

tramp_ventry uses a literal pool, unless CONFIG_RANDOMIZE_BASE is
set in which case it uses the data page as a literal pool because
the data page can be unmapped when running in user-space, which is
required for CPUs vulnerable to meltdown.

Pull this logic out as a macro instead of adding a third copy
of it.

Change-Id: Ic2c62933b6a49c15f572c40e430a83bfa50dedae
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: e18876b5
Git-repo: https://android.googlesource.com/kernel/common/


Signed-off-by: default avatarKishor Krishna Bhat <quic_kishkris@quicinc.com>
parent 005ec074

arch/arm64/kernel/entry.S

+17 −19
Original line number Diff line number Diff line
@@ -1003,6 +1003,16 @@ alternative_else_nop_endif 
	sub	\dst, \dst, PAGE_SIZE

	.endm



	.macro tramp_data_read_var	dst, var

#ifdef CONFIG_RANDOMIZE_BASE

	tramp_data_page		\dst

	add	\dst, \dst, #:lo12:__entry_tramp_data_\var

	ldr	\dst, [\dst]

#else

	ldr	\dst, =\var

#endif

	.endm



#define BHB_MITIGATION_NONE	0

#define BHB_MITIGATION_LOOP	1

#define BHB_MITIGATION_FW	2
@@ -1032,13 +1042,8 @@ alternative_else_nop_endif 
	b	.

2:

	tramp_map_kernel	x30

#ifdef CONFIG_RANDOMIZE_BASE

	tramp_data_page		x30

alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003

	ldr	x30, [x30]

#else

	ldr	x30, =vectors

#endif

	tramp_data_read_var	x30, vectors

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

	msr	vbar_el1, x30

	isb
@@ -1118,7 +1123,12 @@ END(tramp_exit_compat) 
	.align PAGE_SHIFT

	.globl	__entry_tramp_data_start

__entry_tramp_data_start:

__entry_tramp_data_vectors:

	.quad	vectors

#ifdef CONFIG_ARM_SDE_INTERFACE

__entry_tramp_data___sdei_asm_handler:

	.quad	__sdei_asm_handler

#endif /* CONFIG_ARM_SDE_INTERFACE */

	.popsection				// .rodata

#endif /* CONFIG_RANDOMIZE_BASE */

#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
@@ -1250,13 +1260,7 @@ ENTRY(__sdei_asm_entry_trampoline) 
	 */

1:	str	x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)]



#ifdef CONFIG_RANDOMIZE_BASE

	tramp_data_page 	x4

	add	x4, x4, #:lo12:__sdei_asm_trampoline_next_handler

	ldr	x4, [x4]

#else

	ldr	x4, =__sdei_asm_handler

#endif

	tramp_data_read_var	x4, __sdei_asm_handler

	br	x4

ENDPROC(__sdei_asm_entry_trampoline)

NOKPROBE(__sdei_asm_entry_trampoline)
@@ -1279,12 +1283,6 @@ ENDPROC(__sdei_asm_exit_trampoline) 
NOKPROBE(__sdei_asm_exit_trampoline)

	.ltorg

.popsection		// .entry.tramp.text

#ifdef CONFIG_RANDOMIZE_BASE

.pushsection ".rodata", "a"

__sdei_asm_trampoline_next_handler:

	.quad	__sdei_asm_handler

.popsection		// .rodata

#endif /* CONFIG_RANDOMIZE_BASE */

#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */



/*