From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux@armlinux.org.uk, arnd@arndb.de, Ard Biesheuvel <ardb@kernel.org>
Subject: [PATCH] ARM: decompressor: deal with ADR going out of range in efi_enter_kernel()
Date: Tue, 7 Apr 2020 09:46:23 +0200 [thread overview]
Message-ID: <20200407074623.29378-1-ardb@kernel.org> (raw)
Commit 0698fac4ac2a ("efi/arm: Clean EFI stub exit code from cache instead
of avoiding it") introduced a PC-relative reference to 'call_cache_fn' into
efi_enter_kernel(), which lives way at the end of head.S. In some cases,
the ARM version of the ADR instruction does not have sufficient range,
resulting in a build error:
arch/arm/boot/compressed/head.S:1453: Error: invalid constant (fffffffffffffbe4) after fixup
ARM defines an alternative with a wider range, called ADRL, but this does
not exist for Thumb-2. At the same time, the ADR instruction in Thumb-2
has a wider range, and so it does not suffer from the same issue.
So let's switch to ADRL for ARM builds, and keep the ADR for Thumb-2 builds.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm/boot/compressed/head.S | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index cabdd8f4a248..e8e1c866e413 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -1450,7 +1450,8 @@ ENTRY(efi_enter_kernel)
@ running beyond the PoU, and so calling cache_off below from
@ inside the PE/COFF loader allocated region is unsafe unless
@ we explicitly clean it to the PoC.
- adr r0, call_cache_fn @ region of code we will
+ ARM( adrl r0, call_cache_fn )
+ THUMB( adr r0, call_cache_fn ) @ region of code we will
adr r1, 0f @ run with MMU off
bl cache_clean_flush
bl cache_off
--
2.17.1
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next reply other threads:[~2020-04-07 7:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 7:46 Ard Biesheuvel [this message]
2020-04-07 8:06 ` [PATCH] ARM: decompressor: deal with ADR going out of range in efi_enter_kernel() Ard Biesheuvel
2020-04-07 10:13 ` Arnd Bergmann
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