From: Will Deacon <will@kernel.org> Date: 2021-03-03 18:11:05
Hi again,
This is version two of the series I previously posted here:
https://lore.kernel.org/r/20210225125921.13147-1-will@kernel.org
The main change since v1 is that, rather than "fix" the FDT code to
follow the documented behaviour for CMDLINE_EXTEND, I've opted to remove
the thing entirely for arm64 while a less ambiguous and generic
replacement is developed, probably based on either [1] or [2].
I've left the first-patch as-is so that it's easier to incorporate
whatever ends up replacing CMDLINE_EXTEND in future.
Cheers,
Will
[1] https://patchwork.ozlabs.org/project/linuxppc-dev/cover/cover.1554195798.git.christophe.leroy@c-s.fr/
[2] https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20190319232448.45964-2-danielwa@cisco.com/
--->8
Cc: Max Uvarov <redacted>
Cc: Rob Herring <robh@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Doug Anderson <dianders@chromium.org>
Cc: Tyler Hicks <redacted>
Cc: Frank Rowand <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: <redacted>
Cc: <redacted>
Cc: <redacted>
Will Deacon (2):
arm64: cpufeatures: Fix handling of CONFIG_CMDLINE for idreg overrides
arm64: Drop support for CMDLINE_EXTEND
arch/arm64/Kconfig | 6 -----
arch/arm64/kernel/idreg-override.c | 43 ++++++++++++++++--------------
2 files changed, 23 insertions(+), 26 deletions(-)
--
2.30.1.766.gb4fecdf3b7-goog
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From: Will Deacon <will@kernel.org> Date: 2021-03-03 18:11:04
The built-in kernel commandline (CONFIG_CMDLINE) can be configured in
three different ways:
1. CMDLINE_FORCE: Use CONFIG_CMDLINE instead of any bootloader args
2. CMDLINE_EXTEND: Append the bootloader args to CONFIG_CMDLINE
3. CMDLINE_FROM_BOOTLOADER: Only use CONFIG_CMDLINE if there aren't
any bootloader args.
The early cmdline parsing to detect idreg overrides gets (2) and (3)
slightly wrong: in the case of (2) the bootloader args are parsed first
and in the case of (3) the CMDLINE is always parsed.
Fix these issues by moving the bootargs parsing out into a helper
function and following the same logic as that used by the EFI stub.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Fixes: 33200303553d ("arm64: cpufeature: Add an early command-line cpufeature override facility")
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/idreg-override.c | 44 +++++++++++++++++-------------
1 file changed, 25 insertions(+), 19 deletions(-)
From: Rob Herring <robh@kernel.org> Date: 2021-03-04 00:11:04
On Wed, Mar 3, 2021 at 7:50 AM Will Deacon [off-list ref] wrote:
The built-in kernel commandline (CONFIG_CMDLINE) can be configured in
three different ways:
1. CMDLINE_FORCE: Use CONFIG_CMDLINE instead of any bootloader args
2. CMDLINE_EXTEND: Append the bootloader args to CONFIG_CMDLINE
3. CMDLINE_FROM_BOOTLOADER: Only use CONFIG_CMDLINE if there aren't
any bootloader args.
The early cmdline parsing to detect idreg overrides gets (2) and (3)
slightly wrong: in the case of (2) the bootloader args are parsed first
and in the case of (3) the CMDLINE is always parsed.
Fix these issues by moving the bootargs parsing out into a helper
function and following the same logic as that used by the EFI stub.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Fixes: 33200303553d ("arm64: cpufeature: Add an early command-line cpufeature override facility")
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/idreg-override.c | 44 +++++++++++++++++-------------
1 file changed, 25 insertions(+), 19 deletions(-)
It bothers me a bit having command line handling here. It means how
the command line is assembled in 2 places. I guess if we get rid of
ambiguous 'extend' then it's better, but perhaps a better
implementation would be an api get a specific command line parameter.
The main downside would be searching the DT again for each parameter
if we can't store any data in between calls, but there's ways around
that. PowerPC also needs similar functionality in
disabled_on_cmdline().
Anyways, that's all beyond the scope of this.
Rob
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From: Will Deacon <will@kernel.org> Date: 2021-03-04 09:34:55
On Wed, Mar 03, 2021 at 04:30:21PM -0600, Rob Herring wrote:
On Wed, Mar 3, 2021 at 7:50 AM Will Deacon [off-list ref] wrote:
quoted
The built-in kernel commandline (CONFIG_CMDLINE) can be configured in
three different ways:
1. CMDLINE_FORCE: Use CONFIG_CMDLINE instead of any bootloader args
2. CMDLINE_EXTEND: Append the bootloader args to CONFIG_CMDLINE
3. CMDLINE_FROM_BOOTLOADER: Only use CONFIG_CMDLINE if there aren't
any bootloader args.
The early cmdline parsing to detect idreg overrides gets (2) and (3)
slightly wrong: in the case of (2) the bootloader args are parsed first
and in the case of (3) the CMDLINE is always parsed.
Fix these issues by moving the bootargs parsing out into a helper
function and following the same logic as that used by the EFI stub.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Fixes: 33200303553d ("arm64: cpufeature: Add an early command-line cpufeature override facility")
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/idreg-override.c | 44 +++++++++++++++++-------------
1 file changed, 25 insertions(+), 19 deletions(-)
It bothers me a bit having command line handling here. It means how
the command line is assembled in 2 places.
It's more than 2 places, it's also done in the EFI stub; see efi_pe_entry()
in drivers/firmware/efi/libstub/efi-stub.c. That's why I'm pushing on this,
because at the moment the command-line reported by /proc/cmdline doesn't
match the command-line that was parsed there because they stitch it together
in opposite orders when CMDLINE_EXTEND is used.
I guess if we get rid of ambiguous 'extend' then it's better, but perhaps
a better implementation would be an api get a specific command line
parameter. The main downside would be searching the DT again for each
parameter if we can't store any data in between calls, but there's ways
around that. PowerPC also needs similar functionality in
disabled_on_cmdline().
Christophe's patches at least aim to put the assembling all in one place,
although we'll have to see whether or not it can be used in the EFI stub
environment.
Will
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From: Will Deacon <will@kernel.org> Date: 2021-03-03 18:11:04
The documented behaviour for CMDLINE_EXTEND is that the arguments from
the bootloader are appended to the built-in kernel command line. This
also matches the option parsing behaviour for the EFI stub and early ID
register overrides.
Bizarrely, the fdt behaviour is the other way around: appending the
built-in command line to the bootloader arguments, resulting in a
command-line that doesn't necessarily line-up with the parsing order and
definitely doesn't line-up with the documented behaviour.
As it turns out, there is a proposal [1] to replace CMDLINE_EXTEND with
CMDLINE_PREPEND and CMDLINE_APPEND options which should hopefully make
the intended behaviour much clearer. While we wait for those to land,
drop CMDLINE_EXTEND for now as there appears to be little enthusiasm for
changing the current FDT behaviour.
[1] https://lore.kernel.org/lkml/20190319232448.45964-2-danielwa@cisco.com/
Cc: Max Uvarov <redacted>
Cc: Rob Herring <robh@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Doug Anderson <dianders@chromium.org>
Cc: Tyler Hicks <redacted>
Cc: Frank Rowand <redacted>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/CAL_JsqJX=TCCs7=gg486r9TN4NYscMTCLNfqJF9crskKPq-bTg@mail.gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/Kconfig | 6 ------
arch/arm64/kernel/idreg-override.c | 5 +----
2 files changed, 1 insertion(+), 10 deletions(-)
From: Will Deacon <will@kernel.org> Date: 2021-03-08 14:40:52
On Wed, 3 Mar 2021 13:49:25 +0000, Will Deacon wrote:
This is version two of the series I previously posted here:
https://lore.kernel.org/r/20210225125921.13147-1-will@kernel.org
The main change since v1 is that, rather than "fix" the FDT code to
follow the documented behaviour for CMDLINE_EXTEND, I've opted to remove
the thing entirely for arm64 while a less ambiguous and generic
replacement is developed, probably based on either [1] or [2].
[...]