From: James Morse james.morse@arm.com
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 [ Removed SDEI for stable backport ] Signed-off-by: James Morse james.morse@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/entry.S | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-)
--- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -921,6 +921,15 @@ __ni_sys_trace: 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 @@ -951,13 +960,7 @@ __ni_sys_trace: b . 2: tramp_map_kernel x30 -#ifdef CONFIG_RANDOMIZE_BASE - tramp_data_page x30 - isb - 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 @@ -1037,7 +1040,12 @@ 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_trampoline_next_handler: + .quad __sdei_asm_handler +#endif /* CONFIG_ARM_SDE_INTERFACE */ .popsection // .rodata #endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */