On Fri, Mar 18, 2022 at 12:11:32PM +0000, James Morse wrote:
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 x4ENDPROC(__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.
Let me merge this into this commit.
thanks!
greg k-h