From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Scott Wood <oss@buserror.net>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc/32: Fix protection of kernel RAM after freeing unused memory
Date: Fri, 14 Apr 2017 15:11:26 +0200 (CEST) [thread overview]
Message-ID: <20170414131126.AA07A67422@localhost.localdomain> (raw)
As seen below, allthough the init sections have been freed, the
associated memory area is still marked as executable in the
page tables. This patch fixes that.
[ 5.860093] Freeing unused kernel memory: 592K (c0570000 - c0604000)
---[ Start of kernel VM ]---
0xc0000000-0xc0497fff 4704K rw X present dirty accessed shared
0xc0498000-0xc056ffff 864K rw present dirty accessed shared
0xc0570000-0xc059ffff 192K rw X present dirty accessed shared
0xc05a0000-0xc7ffffff 125312K rw present dirty accessed shared
---[ vmalloc() Area ]---
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/mm/mem.c | 3 +++
arch/powerpc/mm/mmu_decl.h | 1 +
arch/powerpc/mm/pgtable_32.c | 20 ++++++++++++++++++++
3 files changed, 24 insertions(+)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9ee536ec0739..e95931c4e6cf 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -401,6 +401,9 @@ void free_initmem(void)
{
ppc_md.progress = ppc_printk_progress;
free_initmem_default(POISON_FREE_INITMEM);
+#ifdef CONFIG_PPC32
+ remap_init_ram();
+#endif
}
#ifdef CONFIG_BLK_DEV_INITRD
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index f988db655e5b..d39d92600839 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -95,6 +95,7 @@ extern void _tlbia(void);
extern void mapin_ram(void);
extern int map_page(unsigned long va, phys_addr_t pa, int flags);
+void remap_init_ram(void);
extern void setbat(int index, unsigned long virt, phys_addr_t phys,
unsigned int size, pgprot_t prot);
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index a65c0b4c0669..d506bd61b629 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -323,6 +323,26 @@ get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
return(retval);
}
+void remap_init_ram(void)
+{
+ unsigned long start = (unsigned long)_sinittext & PAGE_MASK;
+ unsigned long end = (unsigned long)_einittext;
+ unsigned long va;
+
+ for (va = start; va < end; va += PAGE_SIZE) {
+ pte_t *kpte;
+ pmd_t *kpmd;
+ pte_t pte = pfn_pte(__pa(va) >> PAGE_SHIFT, PAGE_KERNEL);
+
+ if (!get_pteptr(&init_mm, va, &kpte, &kpmd))
+ continue;
+ __set_pte_at(&init_mm, va, kpte, pte, 0);
+ wmb();
+ pte_unmap(kpte);
+ }
+ flush_tlb_kernel_range(start, end);
+}
+
#ifdef CONFIG_DEBUG_PAGEALLOC
static int __change_page_attr(struct page *page, pgprot_t prot)
--
2.12.0
next reply other threads:[~2017-04-14 13:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-14 13:11 Christophe Leroy [this message]
2017-04-18 6:40 ` [PATCH] powerpc/32: Fix protection of kernel RAM after freeing unused memory Michael Ellerman
2017-04-18 8:15 ` Christophe LEROY
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