[PATCH v5 2/2] RISC-V: add zbb support to string functions

[Guenter Roeck]

Hi,

On Fri, Jan 13, 2023 at 10:23:01PM +0100, Heiko Stuebner wrote:
> From: Heiko Stuebner <heiko.stuebner at vrull.eu>
> 
> Add handling for ZBB extension and add support for using it as a
> variant for optimized string functions.
> 
> Support for the Zbb-str-variants is limited to the GNU-assembler
> for now, as LLVM has not yet acquired the functionality to
> selectively change the arch option in assembler code.
> This is still under review at
>     https://reviews.llvm.org/D123515
> 
> Co-developed-by: Christoph Muellner <christoph.muellner at vrull.eu>
> Signed-off-by: Christoph Muellner <christoph.muellner at vrull.eu>
> Signed-off-by: Heiko Stuebner <heiko.stuebner at vrull.eu>

With this patch in linux-next, the qemu "virt" emulation no longer finds
a root filesystem. I don't know how it is related, but the problem is
seen for all types of devices I tried to boot from. Booting from initrd
still works.

There are also repeated

WARNING: CPU: 0 PID: 0 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x222/0x2f6

in the log, but that appears to be unrelated.

Guenter

---
bisect log:

# bad: [6ba8a227fd19d19779005fb66ad7562608e1df83] Add linux-next specific files for 20230210
# good: [4ec5183ec48656cec489c49f989c508b68b518e3] Linux 6.2-rc7
git bisect start 'HEAD' 'v6.2-rc7'
# bad: [94613f0efc69ed41f9229ef5c294db3ec37145da] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
git bisect bad 94613f0efc69ed41f9229ef5c294db3ec37145da
# bad: [8928ece68de4371dc6e1d3336d3029c1e18ae3b4] Merge branch 'for_next' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git
git bisect bad 8928ece68de4371dc6e1d3336d3029c1e18ae3b4
# good: [78a9f460e33d103256f3abb38f02f4759710c7dc] soc: document merges
git bisect good 78a9f460e33d103256f3abb38f02f4759710c7dc
# good: [b35b2472ebafa29d0bbe79fbee1da6ef3c4ec619] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git
git bisect good b35b2472ebafa29d0bbe79fbee1da6ef3c4ec619
# bad: [57a87a64b520c37dd49f5fde84d09a4adb391180] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git
git bisect bad 57a87a64b520c37dd49f5fde84d09a4adb391180
# good: [cfc8ba01cc84b24ec6eb293ec9fba893f7cd4581] Merge branch 'clk-next' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git
git bisect good cfc8ba01cc84b24ec6eb293ec9fba893f7cd4581
# good: [6acecfa485d3de955c35a18730c106ddf1e7600e] powerpc/kcsan: Add KCSAN Support
git bisect good 6acecfa485d3de955c35a18730c106ddf1e7600e
# good: [8a16dea453dbc3e834b162640028e505882cd11e] Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git
git bisect good 8a16dea453dbc3e834b162640028e505882cd11e
# good: [6be1ff430dab9fc047762b10b2c9669399ea1f37] riscv: pgtable: Fixup comment for KERN_VIRT_SIZE
git bisect good 6be1ff430dab9fc047762b10b2c9669399ea1f37
# good: [e0c267e03b0c77c9ac79ac08eada41ba8eb1b95f] riscv: module: move find_section to module.h
git bisect good e0c267e03b0c77c9ac79ac08eada41ba8eb1b95f
# good: [e8ad17d2b5f38e595d597a3e2419d6d7cc727b17] riscv: KVM: Switch has_svinval() to riscv_has_extension_unlikely()
git bisect good e8ad17d2b5f38e595d597a3e2419d6d7cc727b17
# bad: [75ab93a244a516d1d3c03c4e27d5d0deff76ebfb] Merge patch series "Zbb string optimizations"
git bisect bad 75ab93a244a516d1d3c03c4e27d5d0deff76ebfb
# bad: [b6fcdb191e36f82336f9b5e126d51c02e7323480] RISC-V: add zbb support to string functions
git bisect bad b6fcdb191e36f82336f9b5e126d51c02e7323480
# good: [56e0790c7f9e59ba6a0f4b59981d1d6fbf43efb0] RISC-V: add infrastructure to allow different str* implementations
git bisect good 56e0790c7f9e59ba6a0f4b59981d1d6fbf43efb0
# first bad commit: [b6fcdb191e36f82336f9b5e126d51c02e7323480] RISC-V: add zbb support to string functions