arm64: kernel: use literal for relocated address of __secondary_switched (e5ebeec8) · Commits · 戴 / test

We can simply use a relocated 64-bit literal to store the address of __secondary_switched(), and the relocation code will ensure that it holds the correct value at secondary entry time, as long as we make sure that the literal is not dereferenced until after we have enabled the MMU. So jump via a small __secondary_switch() function covered by the ID map that performs the literal load and branch-to-register. Acked-by:

Catalin Marinas <catalin.marinas@arm.com> Acked-by:

Mark Rutland <mark.rutland@arm.com> Signed-off-by:

Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by:

Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/head.S

+7 −7

Original line number	Diff line number	Diff line
		@@ -468,9 +468,7 @@ __mmap_switched:
		str x15, [x11, x23]
		b 0b

		2: adr_l x8, kimage_vaddr // make relocated kimage_vaddr
		dc cvac, x8 // value visible to secondaries
		dsb sy // with MMU off
		2:
		#endif

		adr_l sp, initial_sp, x4
		@@ -699,12 +697,9 @@ secondary_startup:
		adrp x26, swapper_pg_dir
		bl __cpu_setup // initialise processor

		ldr x8, kimage_vaddr
		ldr w9, 0f
		sub x27, x8, w9, sxtw // address to jump to after enabling the MMU
		adr_l x27, __secondary_switch // address to jump to after enabling the MMU
		b __enable_mmu
		ENDPROC(secondary_startup)
		0: .long (_text - TEXT_OFFSET) - __secondary_switched

		__secondary_switched:
		adr_l x5, vectors
		@@ -806,3 +801,8 @@ __no_granule_support:
		wfi
		b 1b
		ENDPROC(__no_granule_support)

		__secondary_switch:
		ldr x8, =__secondary_switched
		br x8
		ENDPROC(__secondary_switch)

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