| Message ID | aa54834e9ee5e40179def32ff5834a8a2a02c413.1716714720.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Reimplement huge pages without hugepd on powerpc (8xx, e500, book3s/64) | expand |
On Sun, May 26, 2024 at 11:22:25AM +0200, Christophe Leroy wrote: > Building on 32 bits with pmd_leaf() not returning always false leads > to the following error: > > CC arch/powerpc/mm/pgtable.o > arch/powerpc/mm/pgtable.c: In function '__find_linux_pte': > arch/powerpc/mm/pgtable.c:506:1: error: function may return address of local variable [-Werror=return-local-addr] > 506 | } > | ^ > arch/powerpc/mm/pgtable.c:394:15: note: declared here > 394 | pud_t pud, *pudp; > | ^~~ > arch/powerpc/mm/pgtable.c:394:15: note: declared here > > This is due to pmd_offset() being a no-op in that case. > > So rework it for powerpc/32 so that pXd_offset() are used on real > pointers and not on on-stack copies. > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Maybe this could be folded into the patch that makes pmd_leaf() not returning always false, but no strong feelings: Reviewed-by: Oscar Salvador <osalvador@suse.de>
Le 27/05/2024 à 06:55, Oscar Salvador a écrit : > On Sun, May 26, 2024 at 11:22:25AM +0200, Christophe Leroy wrote: >> Building on 32 bits with pmd_leaf() not returning always false leads >> to the following error: >> >> CC arch/powerpc/mm/pgtable.o >> arch/powerpc/mm/pgtable.c: In function '__find_linux_pte': >> arch/powerpc/mm/pgtable.c:506:1: error: function may return address of local variable [-Werror=return-local-addr] >> 506 | } >> | ^ >> arch/powerpc/mm/pgtable.c:394:15: note: declared here >> 394 | pud_t pud, *pudp; >> | ^~~ >> arch/powerpc/mm/pgtable.c:394:15: note: declared here >> >> This is due to pmd_offset() being a no-op in that case. >> >> So rework it for powerpc/32 so that pXd_offset() are used on real >> pointers and not on on-stack copies. >> >> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > > Maybe this could be folded into the patch that makes pmd_leaf() not returning > always false, but no strong feelings: I prefer to keep it separate, the patch introducing pmd_leaf() is already big enough. > > Reviewed-by: Oscar Salvador <osalvador@suse.de> > >
On Sun, May 26, 2024 at 11:22:25AM +0200, Christophe Leroy wrote: > Building on 32 bits with pmd_leaf() not returning always false leads > to the following error: > > CC arch/powerpc/mm/pgtable.o > arch/powerpc/mm/pgtable.c: In function '__find_linux_pte': > arch/powerpc/mm/pgtable.c:506:1: error: function may return address of local variable [-Werror=return-local-addr] > 506 | } > | ^ > arch/powerpc/mm/pgtable.c:394:15: note: declared here > 394 | pud_t pud, *pudp; > | ^~~ > arch/powerpc/mm/pgtable.c:394:15: note: declared here > > This is due to pmd_offset() being a no-op in that case. > > So rework it for powerpc/32 so that pXd_offset() are used on real > pointers and not on on-stack copies. > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-by: Oscar Salvador <osalvador@suse.de>
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 9e7ba9c3851f..10adef5967a3 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -382,8 +382,10 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, bool *is_thp, unsigned *hpage_shift) { pgd_t *pgdp; +#ifdef CONFIG_PPC64 p4d_t p4d, *p4dp; pud_t pud, *pudp; +#endif pmd_t pmd, *pmdp; pte_t *ret_pte; hugepd_t *hpdp = NULL; @@ -401,8 +403,12 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, * page fault or a page unmap. The return pte_t * is still not * stable. So should be checked there for above conditions. * Top level is an exception because it is folded into p4d. + * + * On PPC32, P4D/PUD/PMD are folded into PGD so go straight to + * PMD level. */ pgdp = pgdir + pgd_index(ea); +#ifdef CONFIG_PPC64 p4dp = p4d_offset(pgdp, ea); p4d = READ_ONCE(*p4dp); pdshift = P4D_SHIFT; @@ -444,6 +450,9 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, pdshift = PMD_SHIFT; pmdp = pmd_offset(&pud, ea); +#else + pmdp = pmd_offset(pud_offset(p4d_offset(pgdp, ea), ea), ea); +#endif pmd = READ_ONCE(*pmdp); /*
Building on 32 bits with pmd_leaf() not returning always false leads to the following error: CC arch/powerpc/mm/pgtable.o arch/powerpc/mm/pgtable.c: In function '__find_linux_pte': arch/powerpc/mm/pgtable.c:506:1: error: function may return address of local variable [-Werror=return-local-addr] 506 | } | ^ arch/powerpc/mm/pgtable.c:394:15: note: declared here 394 | pud_t pud, *pudp; | ^~~ arch/powerpc/mm/pgtable.c:394:15: note: declared here This is due to pmd_offset() being a no-op in that case. So rework it for powerpc/32 so that pXd_offset() are used on real pointers and not on on-stack copies. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- v3: Removed p4dp and pudp locals for PPC32 and add a comment. --- arch/powerpc/mm/pgtable.c | 9 +++++++++ 1 file changed, 9 insertions(+)