On 3/17/22 5:45 AM, Greg Kroah-Hartman wrote:
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 Signed-off-by: James Morse james.morse@arm.com Signed-off-by: Sasha Levin sashal@kernel.org
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 */ /*