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H A DMakefilediff dee2b702 Sat Nov 13 17:57:25 MST 2021 Gustavo A. R. Silva <gustavoars@kernel.org> kconfig: Add support for -Wimplicit-fallthrough

Add Kconfig support for -Wimplicit-fallthrough for both GCC and Clang.

The compiler option is under configuration CC_IMPLICIT_FALLTHROUGH,
which is enabled by default.

Special thanks to Nathan Chancellor who fixed the Clang bug[1][2]. This
bugfix only appears in Clang 14.0.0, so older versions still contain
the bug and -Wimplicit-fallthrough won't be enabled for them, for now.

This concludes a long journey and now we are finally getting rid
of the unintentional fallthrough bug-class in the kernel, entirely. :)

Link: https://github.com/llvm/llvm-project/commit/9ed4a94d6451046a51ef393cd62f00710820a7e8 [1]
Link: https://bugs.llvm.org/show_bug.cgi?id=51094 [2]
Link: https://github.com/KSPP/linux/issues/115
Link: https://github.com/ClangBuiltLinux/linux/issues/236
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff dee2b702 Sat Nov 13 17:57:25 MST 2021 Gustavo A. R. Silva <gustavoars@kernel.org> kconfig: Add support for -Wimplicit-fallthrough

Add Kconfig support for -Wimplicit-fallthrough for both GCC and Clang.

The compiler option is under configuration CC_IMPLICIT_FALLTHROUGH,
which is enabled by default.

Special thanks to Nathan Chancellor who fixed the Clang bug[1][2]. This
bugfix only appears in Clang 14.0.0, so older versions still contain
the bug and -Wimplicit-fallthrough won't be enabled for them, for now.

This concludes a long journey and now we are finally getting rid
of the unintentional fallthrough bug-class in the kernel, entirely. :)

Link: https://github.com/llvm/llvm-project/commit/9ed4a94d6451046a51ef393cd62f00710820a7e8 [1]
Link: https://bugs.llvm.org/show_bug.cgi?id=51094 [2]
Link: https://github.com/KSPP/linux/issues/115
Link: https://github.com/ClangBuiltLinux/linux/issues/236
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff fc02cb2b Tue Nov 02 07:20:58 MDT 2021 Linus Torvalds <torvalds@linux-foundation.org> Merge tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Jakub Kicinski:
"Core:

- Remove socket skb caches

- Add a SO_RESERVE_MEM socket op to forward allocate buffer space and
avoid memory accounting overhead on each message sent

- Introduce managed neighbor entries - added by control plane and
resolved by the kernel for use in acceleration paths (BPF / XDP
right now, HW offload users will benefit as well)

- Make neighbor eviction on link down controllable by userspace to
work around WiFi networks with bad roaming implementations

- vrf: Rework interaction with netfilter/conntrack

- fq_codel: implement L4S style ce_threshold_ect1 marking

- sch: Eliminate unnecessary RCU waits in mini_qdisc_pair_swap()

BPF:

- Add support for new btf kind BTF_KIND_TAG, arbitrary type tagging
as implemented in LLVM14

- Introduce bpf_get_branch_snapshot() to capture Last Branch Records

- Implement variadic trace_printk helper

- Add a new Bloomfilter map type

- Track <8-byte scalar spill and refill

- Access hw timestamp through BPF's __sk_buff

- Disallow unprivileged BPF by default

- Document BPF licensing

Netfilter:

- Introduce egress hook for looking at raw outgoing packets

- Allow matching on and modifying inner headers / payload data

- Add NFT_META_IFTYPE to match on the interface type either from
ingress or egress

Protocols:

- Multi-Path TCP:
- increase default max additional subflows to 2
- rework forward memory allocation
- add getsockopts: MPTCP_INFO, MPTCP_TCPINFO, MPTCP_SUBFLOW_ADDRS

- MCTP flow support allowing lower layer drivers to configure msg
muxing as needed

- Automatic Multicast Tunneling (AMT) driver based on RFC7450

- HSR support the redbox supervision frames (IEC-62439-3:2018)

- Support for the ip6ip6 encapsulation of IOAM

- Netlink interface for CAN-FD's Transmitter Delay Compensation

- Support SMC-Rv2 eliminating the current same-subnet restriction, by
exploiting the UDP encapsulation feature of RoCE adapters

- TLS: add SM4 GCM/CCM crypto support

- Bluetooth: initial support for link quality and audio/codec offload

Driver APIs:

- Add a batched interface for RX buffer allocation in AF_XDP buffer
pool

- ethtool: Add ability to control transceiver modules' power mode

- phy: Introduce supported interfaces bitmap to express MAC
capabilities and simplify PHY code

- Drop rtnl_lock from DSA .port_fdb_{add,del} callbacks

New drivers:

- WiFi driver for Realtek 8852AE 802.11ax devices (rtw89)

- Ethernet driver for ASIX AX88796C SPI device (x88796c)

Drivers:

- Broadcom PHYs
- support 72165, 7712 16nm PHYs
- support IDDQ-SR for additional power savings

- PHY support for QCA8081, QCA9561 PHYs

- NXP DPAA2: support for IRQ coalescing

- NXP Ethernet (enetc): support for software TCP segmentation

- Renesas Ethernet (ravb) - support DMAC and EMAC blocks of
Gigabit-capable IP found on RZ/G2L SoC

- Intel 100G Ethernet
- support for eswitch offload of TC/OvS flow API, including
offload of GRE, VxLAN, Geneve tunneling
- support application device queues - ability to assign Rx and Tx
queues to application threads
- PTP and PPS (pulse-per-second) extensions

- Broadcom Ethernet (bnxt)
- devlink health reporting and device reload extensions

- Mellanox Ethernet (mlx5)
- offload macvlan interfaces
- support HW offload of TC rules involving OVS internal ports
- support HW-GRO and header/data split
- support application device queues

- Marvell OcteonTx2:
- add XDP support for PF
- add PTP support for VF

- Qualcomm Ethernet switch (qca8k): support for QCA8328

- Realtek Ethernet DSA switch (rtl8366rb)
- support bridge offload
- support STP, fast aging, disabling address learning
- support for Realtek RTL8365MB-VC, a 4+1 port 10M/100M/1GE switch

- Mellanox Ethernet/IB switch (mlxsw)
- multi-level qdisc hierarchy offload (e.g. RED, prio and shaping)
- offload root TBF qdisc as port shaper
- support multiple routing interface MAC address prefixes
- support for IP-in-IP with IPv6 underlay

- MediaTek WiFi (mt76)
- mt7921 - ASPM, 6GHz, SDIO and testmode support
- mt7915 - LED and TWT support

- Qualcomm WiFi (ath11k)
- include channel rx and tx time in survey dump statistics
- support for 80P80 and 160 MHz bandwidths
- support channel 2 in 6 GHz band
- spectral scan support for QCN9074
- support for rx decapsulation offload (data frames in 802.3
format)

- Qualcomm phone SoC WiFi (wcn36xx)
- enable Idle Mode Power Save (IMPS) to reduce power consumption
during idle

- Bluetooth driver support for MediaTek MT7922 and MT7921

- Enable support for AOSP Bluetooth extension in Qualcomm WCN399x and
Realtek 8822C/8852A

- Microsoft vNIC driver (mana)
- support hibernation and kexec

- Google vNIC driver (gve)
- support for jumbo frames
- implement Rx page reuse

Refactor:

- Make all writes to netdev->dev_addr go thru helpers, so that we can
add this address to the address rbtree and handle the updates

- Various TCP cleanups and optimizations including improvements to
CPU cache use

- Simplify the gnet_stats, Qdisc stats' handling and remove
qdisc->running sequence counter

- Driver changes and API updates to address devlink locking
deficiencies"

* tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2122 commits)
Revert "net: avoid double accounting for pure zerocopy skbs"
selftests: net: add arp_ndisc_evict_nocarrier
net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter
net: arp: introduce arp_evict_nocarrier sysctl parameter
libbpf: Deprecate AF_XDP support
kbuild: Unify options for BTF generation for vmlinux and modules
selftests/bpf: Add a testcase for 64-bit bounds propagation issue.
bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
net: vmxnet3: remove multiple false checks in vmxnet3_ethtool.c
net: avoid double accounting for pure zerocopy skbs
tcp: rename sk_wmem_free_skb
netdevsim: fix uninit value in nsim_drv_configure_vfs()
selftests/bpf: Fix also no-alu32 strobemeta selftest
bpf: Add missing map_delete_elem method to bloom filter map
selftests/bpf: Add bloom map success test for userspace calls
bpf: Add alignment padding for "map_extra" + consolidate holes
bpf: Bloom filter map naming fixups
selftests/bpf: Add test cases for struct_ops prog
bpf: Add dummy BPF STRUCT_OPS for test purpose
...
diff fc02cb2b Tue Nov 02 07:20:58 MDT 2021 Linus Torvalds <torvalds@linux-foundation.org> Merge tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Jakub Kicinski:
"Core:

- Remove socket skb caches

- Add a SO_RESERVE_MEM socket op to forward allocate buffer space and
avoid memory accounting overhead on each message sent

- Introduce managed neighbor entries - added by control plane and
resolved by the kernel for use in acceleration paths (BPF / XDP
right now, HW offload users will benefit as well)

- Make neighbor eviction on link down controllable by userspace to
work around WiFi networks with bad roaming implementations

- vrf: Rework interaction with netfilter/conntrack

- fq_codel: implement L4S style ce_threshold_ect1 marking

- sch: Eliminate unnecessary RCU waits in mini_qdisc_pair_swap()

BPF:

- Add support for new btf kind BTF_KIND_TAG, arbitrary type tagging
as implemented in LLVM14

- Introduce bpf_get_branch_snapshot() to capture Last Branch Records

- Implement variadic trace_printk helper

- Add a new Bloomfilter map type

- Track <8-byte scalar spill and refill

- Access hw timestamp through BPF's __sk_buff

- Disallow unprivileged BPF by default

- Document BPF licensing

Netfilter:

- Introduce egress hook for looking at raw outgoing packets

- Allow matching on and modifying inner headers / payload data

- Add NFT_META_IFTYPE to match on the interface type either from
ingress or egress

Protocols:

- Multi-Path TCP:
- increase default max additional subflows to 2
- rework forward memory allocation
- add getsockopts: MPTCP_INFO, MPTCP_TCPINFO, MPTCP_SUBFLOW_ADDRS

- MCTP flow support allowing lower layer drivers to configure msg
muxing as needed

- Automatic Multicast Tunneling (AMT) driver based on RFC7450

- HSR support the redbox supervision frames (IEC-62439-3:2018)

- Support for the ip6ip6 encapsulation of IOAM

- Netlink interface for CAN-FD's Transmitter Delay Compensation

- Support SMC-Rv2 eliminating the current same-subnet restriction, by
exploiting the UDP encapsulation feature of RoCE adapters

- TLS: add SM4 GCM/CCM crypto support

- Bluetooth: initial support for link quality and audio/codec offload

Driver APIs:

- Add a batched interface for RX buffer allocation in AF_XDP buffer
pool

- ethtool: Add ability to control transceiver modules' power mode

- phy: Introduce supported interfaces bitmap to express MAC
capabilities and simplify PHY code

- Drop rtnl_lock from DSA .port_fdb_{add,del} callbacks

New drivers:

- WiFi driver for Realtek 8852AE 802.11ax devices (rtw89)

- Ethernet driver for ASIX AX88796C SPI device (x88796c)

Drivers:

- Broadcom PHYs
- support 72165, 7712 16nm PHYs
- support IDDQ-SR for additional power savings

- PHY support for QCA8081, QCA9561 PHYs

- NXP DPAA2: support for IRQ coalescing

- NXP Ethernet (enetc): support for software TCP segmentation

- Renesas Ethernet (ravb) - support DMAC and EMAC blocks of
Gigabit-capable IP found on RZ/G2L SoC

- Intel 100G Ethernet
- support for eswitch offload of TC/OvS flow API, including
offload of GRE, VxLAN, Geneve tunneling
- support application device queues - ability to assign Rx and Tx
queues to application threads
- PTP and PPS (pulse-per-second) extensions

- Broadcom Ethernet (bnxt)
- devlink health reporting and device reload extensions

- Mellanox Ethernet (mlx5)
- offload macvlan interfaces
- support HW offload of TC rules involving OVS internal ports
- support HW-GRO and header/data split
- support application device queues

- Marvell OcteonTx2:
- add XDP support for PF
- add PTP support for VF

- Qualcomm Ethernet switch (qca8k): support for QCA8328

- Realtek Ethernet DSA switch (rtl8366rb)
- support bridge offload
- support STP, fast aging, disabling address learning
- support for Realtek RTL8365MB-VC, a 4+1 port 10M/100M/1GE switch

- Mellanox Ethernet/IB switch (mlxsw)
- multi-level qdisc hierarchy offload (e.g. RED, prio and shaping)
- offload root TBF qdisc as port shaper
- support multiple routing interface MAC address prefixes
- support for IP-in-IP with IPv6 underlay

- MediaTek WiFi (mt76)
- mt7921 - ASPM, 6GHz, SDIO and testmode support
- mt7915 - LED and TWT support

- Qualcomm WiFi (ath11k)
- include channel rx and tx time in survey dump statistics
- support for 80P80 and 160 MHz bandwidths
- support channel 2 in 6 GHz band
- spectral scan support for QCN9074
- support for rx decapsulation offload (data frames in 802.3
format)

- Qualcomm phone SoC WiFi (wcn36xx)
- enable Idle Mode Power Save (IMPS) to reduce power consumption
during idle

- Bluetooth driver support for MediaTek MT7922 and MT7921

- Enable support for AOSP Bluetooth extension in Qualcomm WCN399x and
Realtek 8822C/8852A

- Microsoft vNIC driver (mana)
- support hibernation and kexec

- Google vNIC driver (gve)
- support for jumbo frames
- implement Rx page reuse

Refactor:

- Make all writes to netdev->dev_addr go thru helpers, so that we can
add this address to the address rbtree and handle the updates

- Various TCP cleanups and optimizations including improvements to
CPU cache use

- Simplify the gnet_stats, Qdisc stats' handling and remove
qdisc->running sequence counter

- Driver changes and API updates to address devlink locking
deficiencies"

* tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2122 commits)
Revert "net: avoid double accounting for pure zerocopy skbs"
selftests: net: add arp_ndisc_evict_nocarrier
net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter
net: arp: introduce arp_evict_nocarrier sysctl parameter
libbpf: Deprecate AF_XDP support
kbuild: Unify options for BTF generation for vmlinux and modules
selftests/bpf: Add a testcase for 64-bit bounds propagation issue.
bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
net: vmxnet3: remove multiple false checks in vmxnet3_ethtool.c
net: avoid double accounting for pure zerocopy skbs
tcp: rename sk_wmem_free_skb
netdevsim: fix uninit value in nsim_drv_configure_vfs()
selftests/bpf: Fix also no-alu32 strobemeta selftest
bpf: Add missing map_delete_elem method to bloom filter map
selftests/bpf: Add bloom map success test for userspace calls
bpf: Add alignment padding for "map_extra" + consolidate holes
bpf: Bloom filter map naming fixups
selftests/bpf: Add test cases for struct_ops prog
bpf: Add dummy BPF STRUCT_OPS for test purpose
...
diff b7b98f86 Mon Nov 01 20:59:45 MDT 2021 Jakub Kicinski <kuba@kernel.org> Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2021-11-01

We've added 181 non-merge commits during the last 28 day(s) which contain
a total of 280 files changed, 11791 insertions(+), 5879 deletions(-).

The main changes are:

1) Fix bpf verifier propagation of 64-bit bounds, from Alexei.

2) Parallelize bpf test_progs, from Yucong and Andrii.

3) Deprecate various libbpf apis including af_xdp, from Andrii, Hengqi, Magnus.

4) Improve bpf selftests on s390, from Ilya.

5) bloomfilter bpf map type, from Joanne.

6) Big improvements to JIT tests especially on Mips, from Johan.

7) Support kernel module function calls from bpf, from Kumar.

8) Support typeless and weak ksym in light skeleton, from Kumar.

9) Disallow unprivileged bpf by default, from Pawan.

10) BTF_KIND_DECL_TAG support, from Yonghong.

11) Various bpftool cleanups, from Quentin.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (181 commits)
libbpf: Deprecate AF_XDP support
kbuild: Unify options for BTF generation for vmlinux and modules
selftests/bpf: Add a testcase for 64-bit bounds propagation issue.
bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
selftests/bpf: Fix also no-alu32 strobemeta selftest
bpf: Add missing map_delete_elem method to bloom filter map
selftests/bpf: Add bloom map success test for userspace calls
bpf: Add alignment padding for "map_extra" + consolidate holes
bpf: Bloom filter map naming fixups
selftests/bpf: Add test cases for struct_ops prog
bpf: Add dummy BPF STRUCT_OPS for test purpose
bpf: Factor out helpers for ctx access checking
bpf: Factor out a helper to prepare trampoline for struct_ops prog
selftests, bpf: Fix broken riscv build
riscv, libbpf: Add RISC-V (RV64) support to bpf_tracing.h
tools, build: Add RISC-V to HOSTARCH parsing
riscv, bpf: Increase the maximum number of iterations
selftests, bpf: Add one test for sockmap with strparser
selftests, bpf: Fix test_txmsg_ingress_parser error
...
====================

Link: https://lore.kernel.org/r/20211102013123.9005-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff 5f6e0fe0 Wed Jun 09 20:03:31 MDT 2021 Masahiro Yamada <masahiroy@kernel.org> parisc: Fix compile failure when building 64-bit kernel natively

Commit 23243c1ace9f ("arch: use cross_compiling to check whether it is
a cross build or not") broke 64-bit parisc builds on 32-bit parisc
systems.

Helge mentioned:
- 64-bit parisc userspace is not supported yet [1]
- hppa gcc does not support "-m64" flag [2]

That means, parisc developers working on a 32-bit parisc machine need
to use hppa64-linux-gnu-gcc (cross compiler) for building the 64-bit
parisc kernel.

After the offending commit, gcc is used in such a case because
both $(SRCARCH) and $(SUBARCH) are 'parisc', hence cross_compiling is
unset.

A correct way is to introduce ARCH=parisc64 because building the 64-bit
parisc kernel on a 32-bit parisc system is not exactly a native build,
but rather a semi-cross build.

[1]: https://lore.kernel.org/linux-parisc/5dfd81eb-c8ca-b7f5-e80e-8632767c022d@gmx.de/#t
[2]: https://lore.kernel.org/linux-parisc/89515325-fc21-31da-d238-6f7a9abbf9a0@gmx.de/

Fixes: 23243c1ace9f ("arch: use cross_compiling to check whether it is a cross build or not")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reported-by: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>
Cc: <stable@vger.kernel.org> # v5.13+
Signed-off-by: Helge Deller <deller@gmx.de>
diff 5f6e0fe0 Wed Jun 09 20:03:31 MDT 2021 Masahiro Yamada <masahiroy@kernel.org> parisc: Fix compile failure when building 64-bit kernel natively

Commit 23243c1ace9f ("arch: use cross_compiling to check whether it is
a cross build or not") broke 64-bit parisc builds on 32-bit parisc
systems.

Helge mentioned:
- 64-bit parisc userspace is not supported yet [1]
- hppa gcc does not support "-m64" flag [2]

That means, parisc developers working on a 32-bit parisc machine need
to use hppa64-linux-gnu-gcc (cross compiler) for building the 64-bit
parisc kernel.

After the offending commit, gcc is used in such a case because
both $(SRCARCH) and $(SUBARCH) are 'parisc', hence cross_compiling is
unset.

A correct way is to introduce ARCH=parisc64 because building the 64-bit
parisc kernel on a 32-bit parisc system is not exactly a native build,
but rather a semi-cross build.

[1]: https://lore.kernel.org/linux-parisc/5dfd81eb-c8ca-b7f5-e80e-8632767c022d@gmx.de/#t
[2]: https://lore.kernel.org/linux-parisc/89515325-fc21-31da-d238-6f7a9abbf9a0@gmx.de/

Fixes: 23243c1ace9f ("arch: use cross_compiling to check whether it is a cross build or not")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reported-by: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>
Cc: <stable@vger.kernel.org> # v5.13+
Signed-off-by: Helge Deller <deller@gmx.de>
diff 6072b2c4 Sat Jul 31 20:53:46 MDT 2021 Masahiro Yamada <masahiroy@kernel.org> kbuild: warn if a different compiler is used for external module builds

It is always safe to use the same compiler for the kernel and external
modules, but in reality, some distributions such as Fedora release a
different version of GCC from the one used for building the kernel.

There was a long discussion about mixing different compilers [1].

I do not repeat it here, but at least, showing a heads up in that
case is better than nothing.

Linus suggested [2]:
And a warning might be more palatable even if different compiler
version work fine together. Just a heads up on "it looks like you
might be mixing compiler versions" is a valid note, and isn't
necessarily wrong. Even when they work well together, maybe you want
to have people at least _aware_ of it.

This commit shows a warning unless the compiler is exactly the same.

warning: the compiler differs from the one used to build the kernel
The kernel was built by: gcc (GCC) 11.1.1 20210531 (Red Hat 11.1.1-3)
You are using: gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)

Check the difference, and if it is OK with you, please proceed at your
risk.

To avoid the locale issue as in commit bcbcf50f5218 ("kbuild: fix
ld-version.sh to not be affected by locale"), pass LC_ALL=C to
"$(CC) --version".

[1] https://lore.kernel.org/linux-hardening/efe6b039a544da8215d5e54aa7c4b6d1986fc2b0.1611607264.git.jpoimboe@redhat.com/
[2] https://lore.kernel.org/lkml/CAHk-=wgjwhDy-y4mQh34L+2aF=n6BjzHdqAW2=8wri5x7O04pA@mail.gmail.com/

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
diff 6072b2c4 Sat Jul 31 20:53:46 MDT 2021 Masahiro Yamada <masahiroy@kernel.org> kbuild: warn if a different compiler is used for external module builds

It is always safe to use the same compiler for the kernel and external
modules, but in reality, some distributions such as Fedora release a
different version of GCC from the one used for building the kernel.

There was a long discussion about mixing different compilers [1].

I do not repeat it here, but at least, showing a heads up in that
case is better than nothing.

Linus suggested [2]:
And a warning might be more palatable even if different compiler
version work fine together. Just a heads up on "it looks like you
might be mixing compiler versions" is a valid note, and isn't
necessarily wrong. Even when they work well together, maybe you want
to have people at least _aware_ of it.

This commit shows a warning unless the compiler is exactly the same.

warning: the compiler differs from the one used to build the kernel
The kernel was built by: gcc (GCC) 11.1.1 20210531 (Red Hat 11.1.1-3)
You are using: gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)

Check the difference, and if it is OK with you, please proceed at your
risk.

To avoid the locale issue as in commit bcbcf50f5218 ("kbuild: fix
ld-version.sh to not be affected by locale"), pass LC_ALL=C to
"$(CC) --version".

[1] https://lore.kernel.org/linux-hardening/efe6b039a544da8215d5e54aa7c4b6d1986fc2b0.1611607264.git.jpoimboe@redhat.com/
[2] https://lore.kernel.org/lkml/CAHk-=wgjwhDy-y4mQh34L+2aF=n6BjzHdqAW2=8wri5x7O04pA@mail.gmail.com/

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
diff 6072b2c4 Sat Jul 31 20:53:46 MDT 2021 Masahiro Yamada <masahiroy@kernel.org> kbuild: warn if a different compiler is used for external module builds

It is always safe to use the same compiler for the kernel and external
modules, but in reality, some distributions such as Fedora release a
different version of GCC from the one used for building the kernel.

There was a long discussion about mixing different compilers [1].

I do not repeat it here, but at least, showing a heads up in that
case is better than nothing.

Linus suggested [2]:
And a warning might be more palatable even if different compiler
version work fine together. Just a heads up on "it looks like you
might be mixing compiler versions" is a valid note, and isn't
necessarily wrong. Even when they work well together, maybe you want
to have people at least _aware_ of it.

This commit shows a warning unless the compiler is exactly the same.

warning: the compiler differs from the one used to build the kernel
The kernel was built by: gcc (GCC) 11.1.1 20210531 (Red Hat 11.1.1-3)
You are using: gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)

Check the difference, and if it is OK with you, please proceed at your
risk.

To avoid the locale issue as in commit bcbcf50f5218 ("kbuild: fix
ld-version.sh to not be affected by locale"), pass LC_ALL=C to
"$(CC) --version".

[1] https://lore.kernel.org/linux-hardening/efe6b039a544da8215d5e54aa7c4b6d1986fc2b0.1611607264.git.jpoimboe@redhat.com/
[2] https://lore.kernel.org/lkml/CAHk-=wgjwhDy-y4mQh34L+2aF=n6BjzHdqAW2=8wri5x7O04pA@mail.gmail.com/

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Completed in 828 milliseconds