From: Christophe Leroy christophe.leroy@csgroup.eu
[ Upstream commit 6042a1652d643d1d34fa89bb314cb102960c0800 ]
Since commit 4291d085b0b0 ("powerpc/32s: Make pte_update() non atomic on 603 core"), pte_update() has been using mmu_has_feature(MMU_FTR_HPTE_TABLE) to avoid a useless atomic operation on 603 cores.
When kasan_early_init() sets up the early zero shadow, it uses __set_pte_at(). On book3s/32, __set_pte_at() calls pte_update() when CONFIG_SMP is selected in order to ensure the preservation of _PAGE_HASHPTE in case of concurrent update of the PTE. But that's too early for mmu_has_feature(), so when CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG is selected, mmu_has_feature() calls printk(). That's too early to call printk() because KASAN early zero shadow page is not set up yet. It leads to a deadlock.
However, when kasan_early_init() is called, there is only one CPU running and no risk of concurrent PTE update. So __set_pte_at() can be called with the 'percpu' flag. With that flag set, the PTE is written directly instead of being written via pte_update().
Fixes: 4291d085b0b0 ("powerpc/32s: Make pte_update() non atomic on 603 core") Reported-by: Erhard Furtner erhard_f@mailbox.org Signed-off-by: Christophe Leroy christophe.leroy@csgroup.eu Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/2ee707512b8b212b079b877f4ceb525a1606a3fb.165665556... Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/mm/kasan/kasan_init_32.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c index f3e4d069e0ba..a70828a6d935 100644 --- a/arch/powerpc/mm/kasan/kasan_init_32.c +++ b/arch/powerpc/mm/kasan/kasan_init_32.c @@ -25,7 +25,7 @@ static void __init kasan_populate_pte(pte_t *ptep, pgprot_t prot) int i;
for (i = 0; i < PTRS_PER_PTE; i++, ptep++) - __set_pte_at(&init_mm, va, ptep, pfn_pte(PHYS_PFN(pa), prot), 0); + __set_pte_at(&init_mm, va, ptep, pfn_pte(PHYS_PFN(pa), prot), 1); }
int __init kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_end)