| Message ID | 20200407074623.29378-1-ardb@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | a94691680bace7e1404e4f235badb74e30467e86 |
| Headers | show |
| Series | ARM: decompressor: deal with ADR going out of range in efi_enter_kernel() | expand |
On Tue, 7 Apr 2020 at 09:46, Ard Biesheuvel <ardb@kernel.org> wrote: > > 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> If nobody has any objections, I'll take this as a EFI fix. > --- > 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 >
On Tue, Apr 7, 2020 at 10:06 AM Ard Biesheuvel <ardb@kernel.org> wrote: > > On Tue, 7 Apr 2020 at 09:46, Ard Biesheuvel <ardb@kernel.org> wrote: > > > > 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> > > If nobody has any objections, I'll take this as a EFI fix. I've added it to my randconfig build tree. If you don't hear back from me today, you can add my Tested-by: Arnd Bergmann <arnd@arndb.de>
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
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(-)