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Mon, 15 Jun 2020 12:57:59 +0000 (UTC) Message-Id: <341688399c1b102756046d19ea6ce39db1ae4742.1592225558.git.christophe.leroy@csgroup.eu> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH 3/3] powerpc/8xx: Provide ptep_get() with 16k pages To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Will Deacon , Andrew Morton , "Peter Zijlstra (Intel)" Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org Date: Mon, 15 Jun 2020 12:57:59 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org READ_ONCE() now enforces atomic read, which leads to: CC mm/gup.o In file included from ./include/linux/kernel.h:11:0, from mm/gup.c:2: In function 'gup_hugepte.constprop', inlined from 'gup_huge_pd.isra.79' at mm/gup.c:2465:8: ./include/linux/compiler.h:392:38: error: call to '__compiletime_assert_222' declared with attribute error: Unsupported access size for {READ,WRITE}_ONCE(). _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ ./include/linux/compiler.h:373:4: note: in definition of macro '__compiletime_assert' prefix ## suffix(); \ ^ ./include/linux/compiler.h:392:2: note: in expansion of macro '_compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ ./include/linux/compiler.h:405:2: note: in expansion of macro 'compiletime_assert' compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \ ^ ./include/linux/compiler.h:291:2: note: in expansion of macro 'compiletime_assert_rwonce_type' compiletime_assert_rwonce_type(x); \ ^ mm/gup.c:2428:8: note: in expansion of macro 'READ_ONCE' pte = READ_ONCE(*ptep); ^ In function 'gup_get_pte', inlined from 'gup_pte_range' at mm/gup.c:2228:9, inlined from 'gup_pmd_range' at mm/gup.c:2613:15, inlined from 'gup_pud_range' at mm/gup.c:2641:15, inlined from 'gup_p4d_range' at mm/gup.c:2666:15, inlined from 'gup_pgd_range' at mm/gup.c:2694:15, inlined from 'internal_get_user_pages_fast' at mm/gup.c:2795:3: ./include/linux/compiler.h:392:38: error: call to '__compiletime_assert_219' declared with attribute error: Unsupported access size for {READ,WRITE}_ONCE(). _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ ./include/linux/compiler.h:373:4: note: in definition of macro '__compiletime_assert' prefix ## suffix(); \ ^ ./include/linux/compiler.h:392:2: note: in expansion of macro '_compiletime_assert' _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ ./include/linux/compiler.h:405:2: note: in expansion of macro 'compiletime_assert' compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \ ^ ./include/linux/compiler.h:291:2: note: in expansion of macro 'compiletime_assert_rwonce_type' compiletime_assert_rwonce_type(x); \ ^ mm/gup.c:2199:9: note: in expansion of macro 'READ_ONCE' return READ_ONCE(*ptep); ^ make[2]: *** [mm/gup.o] Error 1 Define ptep_get() on 8xx when using 16k pages. Fixes: 2ab3a0a02905 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses") Cc: Will Deacon Signed-off-by: Christophe Leroy --- arch/powerpc/include/asm/nohash/32/pgtable.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h index b56f14160ae5..77addb599ce7 100644 --- a/arch/powerpc/include/asm/nohash/32/pgtable.h +++ b/arch/powerpc/include/asm/nohash/32/pgtable.h @@ -286,6 +286,16 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, return __pte(pte_update(mm, addr, ptep, ~0, 0, 0)); } +#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PPC_16K_PAGES) +#define __HAVE_ARCH_PTEP_GET +static inline pte_t ptep_get(pte_t *ptep) +{ + pte_t pte = {READ_ONCE(ptep->pte), 0, 0, 0}; + + return pte; +} +#endif + #define __HAVE_ARCH_PTEP_SET_WRPROTECT static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep) -- 2.25.0