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arm64: entry: Add macro for reading symbol addresses from the trampoline

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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.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
James Morse
2021-11-25 14:25:34 +00:00
committed by Greg Kroah-Hartman
parent 3f21b7e355
commit 56cf5326bd
1 changed files with 16 additions and 20 deletions
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36
arch/arm64/kernel/entry.S
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@@ -816,6 +816,15 @@ alternative_else_nop_endif
sub \dst, \dst, PAGE_SIZE sub \dst, \dst, PAGE_SIZE
.endm .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_NONE 0
#define BHB_MITIGATION_LOOP 1 #define BHB_MITIGATION_LOOP 1
@@ -846,13 +855,8 @@ alternative_else_nop_endif
b . b .
2: 2:
tramp_map_kernel x30 tramp_map_kernel x30
#ifdef CONFIG_RANDOMIZE_BASE
tramp_data_page x30
alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
ldr x30, [x30] tramp_data_read_var x30, vectors
#else
ldr x30, =vectors
#endif
alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM
prfm plil1strm, [x30, #(1b - \vector_start)] prfm plil1strm, [x30, #(1b - \vector_start)]
alternative_else_nop_endif alternative_else_nop_endif
@@ -935,7 +939,12 @@ SYM_CODE_END(tramp_exit_compat)
.pushsection ".rodata", "a" .pushsection ".rodata", "a"
.align PAGE_SHIFT .align PAGE_SHIFT
SYM_DATA_START(__entry_tramp_data_start) SYM_DATA_START(__entry_tramp_data_start)
__entry_tramp_data_vectors:
.quad vectors .quad vectors
#ifdef CONFIG_ARM_SDE_INTERFACE
__entry_tramp_data___sdei_asm_handler:
.quad __sdei_asm_handler
#endif /* CONFIG_ARM_SDE_INTERFACE */
SYM_DATA_END(__entry_tramp_data_start) SYM_DATA_END(__entry_tramp_data_start)
.popsection // .rodata .popsection // .rodata
#endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_RANDOMIZE_BASE */
@@ -1066,13 +1075,7 @@ SYM_CODE_START(__sdei_asm_entry_trampoline)
*/ */
1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)]
#ifdef CONFIG_RANDOMIZE_BASE tramp_data_read_var x4, __sdei_asm_handler
tramp_data_page x4
add x4, x4, #:lo12:__sdei_asm_trampoline_next_handler
ldr x4, [x4]
#else
ldr x4, =__sdei_asm_handler
#endif
br x4 br x4
SYM_CODE_END(__sdei_asm_entry_trampoline) SYM_CODE_END(__sdei_asm_entry_trampoline)
NOKPROBE(__sdei_asm_entry_trampoline) NOKPROBE(__sdei_asm_entry_trampoline)
@@ -1095,13 +1098,6 @@ SYM_CODE_END(__sdei_asm_exit_trampoline)
NOKPROBE(__sdei_asm_exit_trampoline) NOKPROBE(__sdei_asm_exit_trampoline)
.ltorg .ltorg
.popsection // .entry.tramp.text .popsection // .entry.tramp.text
#ifdef CONFIG_RANDOMIZE_BASE
.pushsection ".rodata", "a"
SYM_DATA_START(__sdei_asm_trampoline_next_handler)
.quad __sdei_asm_handler
SYM_DATA_END(__sdei_asm_trampoline_next_handler)
.popsection // .rodata
#endif /* CONFIG_RANDOMIZE_BASE */
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
/* /*