Messages in this thread Patch in this message | | | Subject | Re: [PATCH 5.4 18/43] arm64: entry: Add macro for reading symbol addresses from the trampoline | From | James Morse <> | Date | Fri, 18 Mar 2022 12:11:32 +0000 |
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Hi Florian,
On 3/17/22 8:48 PM, Florian Fainelli wrote: > 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
... and with CONFIG_RANDOMIZE_BASE turned off, which is why allyesconfig didn't catch it. This is because I kept the next_handler bit of the label when it conflicted, which isn't needed because the __entry_tramp bit added by the macro serves the same purpose.
The below diff fixes it: ----------%<---------- diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index e4b5a15c2e2e..cfc0bb6c49f7 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -1190,7 +1190,7 @@ __entry_tramp_data_start: __entry_tramp_data_vectors: .quad vectors #ifdef CONFIG_ARM_SDE_INTERFACE -__entry_tramp_data___sdei_asm_trampoline_next_handler: +__entry_tramp_data___sdei_asm_handler: .quad __sdei_asm_handler #endif /* CONFIG_ARM_SDE_INTERFACE */ .popsection // .rodata @@ -1319,7 +1319,7 @@ ENTRY(__sdei_asm_entry_trampoline) */ 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] - tramp_data_read_var x4, __sdei_asm_trampoline_next_handler + tramp_data_read_var x4, __sdei_asm_handler br x4 ENDPROC(__sdei_asm_entry_trampoline) NOKPROBE(__sdei_asm_entry_trampoline) ----------%<---------- Good news - this didn't happen with v5.10.
I don't see this in v5.4.185 yet.
Greg/Sasha, what is least work for you?: A new version of this patch, A fixup on top of the series, Reposting the series with this fixed.
Thanks for catching this!
James
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