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| author | Ard Biesheuvel <ardb@kernel.org> | 2022-06-22 18:10:10 +0200 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2022-06-24 14:08:30 +0200 |
| commit | 1c9a8e87680870d5daf1eaa6314373dcc156ac15 (patch) | |
| tree | 7795f36f44351c6debfe7fc04d840d31ba3c9502 /arch/arm64/kernel/entry.S | |
| parent | arm64: mm: install KPTI nG mappings with MMU enabled (diff) | |
| download | linux-1c9a8e87680870d5daf1eaa6314373dcc156ac15.tar.xz linux-1c9a8e87680870d5daf1eaa6314373dcc156ac15.zip | |
arm64: entry: simplify trampoline data page
Get rid of some clunky open coded arithmetic on section addresses, by
emitting the trampoline data variables into a separate, dedicated r/o
data section, and putting it at the next page boundary. This way, we can
access the literals via single LDR instruction.
While at it, get rid of other, implicit literals, and use ADRP/ADD or
MOVZ/MOVK sequences, as appropriate. Note that the latter are only
supported for CONFIG_RELOCATABLE=n (which is usually the case if
CONFIG_RANDOMIZE_BASE=n), so update the CPP conditionals to reflect
this.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220622161010.3845775-1-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 53 |
1 files changed, 22 insertions, 31 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 5b82b9292400..254fe31c03a0 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -636,18 +636,28 @@ alternative_else_nop_endif */ .endm - .macro tramp_data_page dst - adr_l \dst, .entry.tramp.text - 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] + .macro tramp_data_read_var dst, var +#ifdef CONFIG_RELOCATABLE + ldr \dst, .L__tramp_data_\var + .ifndef .L__tramp_data_\var + .pushsection ".entry.tramp.rodata", "a", %progbits + .align 3 +.L__tramp_data_\var: + .quad \var + .popsection + .endif #else - ldr \dst, =\var + /* + * As !RELOCATABLE implies !RANDOMIZE_BASE the address is always a + * compile time constant (and hence not secret and not worth hiding). + * + * As statically allocated kernel code and data always live in the top + * 47 bits of the address space we can sign-extend bit 47 and avoid an + * instruction to load the upper 16 bits (which must be 0xFFFF). + */ + movz \dst, :abs_g2_s:\var + movk \dst, :abs_g1_nc:\var + movk \dst, :abs_g0_nc:\var #endif .endm @@ -695,7 +705,7 @@ alternative_else_nop_endif msr vbar_el1, x30 isb .else - ldr x30, =vectors + adr_l x30, vectors .endif // \kpti == 1 .if \bhb == BHB_MITIGATION_FW @@ -764,24 +774,7 @@ SYM_CODE_END(tramp_exit_native) SYM_CODE_START(tramp_exit_compat) tramp_exit 32 SYM_CODE_END(tramp_exit_compat) - - .ltorg .popsection // .entry.tramp.text -#ifdef CONFIG_RANDOMIZE_BASE - .pushsection ".rodata", "a" - .align PAGE_SHIFT -SYM_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 */ -__entry_tramp_data_this_cpu_vector: - .quad this_cpu_vector -SYM_DATA_END(__entry_tramp_data_start) - .popsection // .rodata -#endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ /* @@ -932,7 +925,6 @@ NOKPROBE(call_on_irq_stack) * This clobbers x4, __sdei_handler() will restore this from firmware's * copy. */ -.ltorg .pushsection ".entry.tramp.text", "ax" SYM_CODE_START(__sdei_asm_entry_trampoline) mrs x4, ttbr1_el1 @@ -967,7 +959,6 @@ SYM_CODE_START(__sdei_asm_exit_trampoline) 1: sdei_handler_exit exit_mode=x2 SYM_CODE_END(__sdei_asm_exit_trampoline) NOKPROBE(__sdei_asm_exit_trampoline) - .ltorg .popsection // .entry.tramp.text #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ |