On 3/17/22 5:45 AM, Greg Kroah-Hartman wrote: > From: James Morse <james.morse@xxxxxxx> > > 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@xxxxxxx> > Signed-off-by: James Morse <james.morse@xxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> This commit causes a linking failure with CONFIG_ARM_SDE_INTERFACE=y enabled in the kernel: LD .tmp_vmlinux.kallsyms1 /local/users/fainelli/buildroot/output/arm64/host/bin/aarch64-linux-ld: arch/arm64/kernel/entry.o: in function `__sdei_asm_exit_trampoline': /local/users/fainelli/buildroot/output/arm64/build/linux-custom/arch/arm64/kernel/entry.S:1352: undefined reference to `__sdei_asm_trampoline_next_handler' make[2]: *** [Makefile:1100: vmlinux] Error 1 make[1]: *** [package/pkg-generic.mk:295: /local/users/fainelli/buildroot/output/arm64/build/linux-custom/.stamp_built] Error 2 make: *** [Makefile:27: _all] Error 2 > --- > arch/arm64/kernel/entry.S | 35 ++++++++++++++++------------------- > 1 file changed, 16 insertions(+), 19 deletions(-) > > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index 14351ee5e812..e4b5a15c2e2e 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -1063,6 +1063,15 @@ 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 > @@ -1093,13 +1102,8 @@ 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 > alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM > prfm plil1strm, [x30, #(1b - \vector_start)] > alternative_else_nop_endif > @@ -1183,7 +1187,12 @@ 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 */ > @@ -1310,13 +1319,7 @@ 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_trampoline_next_handler > br x4 > ENDPROC(__sdei_asm_entry_trampoline) > NOKPROBE(__sdei_asm_entry_trampoline) > @@ -1339,12 +1342,6 @@ 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 */ > > /* > -- Florian
