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compact: workaround for GPL-only symbols on riscv from Linux 6.2 

Since Linux 6.2, the implementation of flush_dcache_page on riscv
references GPL-only symbol `PageHuge`, breaking the build of zfs.

This patch uses existing mechanism to override flush_dcache_page,
removing the call to `PageHuge`. According to comments in kernel,
it is only used to do some check against HugeTLB pages, which only
exist in userspace. ZFS uses flush_dcache_page only on kernel pages,
thus this patch will not introduce any behaviour change.

See also: torvalds/linux@d33deda, openzfs/zfs@589f59b

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Shengqi Chen <harry-chen@outlook.com>
Closes #14974 
Closes #15627
This commit is contained in:
Shengqi Chen 2023-12-07 04:37:50 +08:00 committed by GitHub
parent 687e4d7f9c
commit 86239a5b9c
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 22 additions and 4 deletions
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5
config/kernel-flush_dcache_page.m4
View File

@ -1,7 +1,8 @@
dnl #
dnl # Starting from Linux 5.13, flush_dcache_page() becomes an inline
dnl # function and may indirectly referencing GPL-only cpu_feature_keys on
dnl # powerpc
dnl # function and may indirectly referencing GPL-only symbols:
dnl # on powerpc: cpu_feature_keys
dnl # on riscv: PageHuge (added from 6.2)
dnl #
dnl #

6
config/kernel.m4
View File

@ -168,6 +168,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
ZFS_AC_KERNEL_SRC_CPU_HAS_FEATURE
ZFS_AC_KERNEL_SRC_FLUSH_DCACHE_PAGE
;;
riscv*)
ZFS_AC_KERNEL_SRC_FLUSH_DCACHE_PAGE
;;
esac
AC_MSG_CHECKING([for available kernel interfaces])
@ -310,6 +313,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
ZFS_AC_KERNEL_CPU_HAS_FEATURE
ZFS_AC_KERNEL_FLUSH_DCACHE_PAGE
;;
riscv*)
ZFS_AC_KERNEL_FLUSH_DCACHE_PAGE
;;
esac
])

15
include/os/linux/kernel/linux/dcache_compat.h
View File

@ -42,8 +42,8 @@
/*
* Starting from Linux 5.13, flush_dcache_page() becomes an inline function
* and under some configurations, may indirectly referencing GPL-only
* cpu_feature_keys on powerpc. Override this function when it is detected
* being GPL-only.
* symbols, e.g., cpu_feature_keys on powerpc and PageHuge on riscv.
* Override this function when it is detected being GPL-only.
*/
#if defined __powerpc__ && defined HAVE_FLUSH_DCACHE_PAGE_GPL_ONLY
#include <linux/simd_powerpc.h>
@ -53,6 +53,17 @@
clear_bit(PG_dcache_clean, &(page)->flags); \
} while (0)
#endif
/*
* For riscv implementation, the use of PageHuge can be safely removed.
* Because it handles pages allocated by HugeTLB, while flush_dcache_page
* in zfs module is only called on kernel pages.
*/
#if defined __riscv && defined HAVE_FLUSH_DCACHE_PAGE_GPL_ONLY
#define flush_dcache_page(page) do { \
if (test_bit(PG_dcache_clean, &(page)->flags)) \
clear_bit(PG_dcache_clean, &(page)->flags); \
} while (0)
#endif
/*
* 2.6.30 API change,