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Message-Id: <42e7e2e9b74af526523fb5a1451fdb29cfe2687a.1539060806.git.christophe.leroy@c-s.fr>
Date: Tue, 9 Oct 2018 05:21:32 +0000 (UTC)
From: Christophe Leroy <christophe.leroy@....fr>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/mm: make NULL pointer deferences explicit on bad page
faults.
As several other arches including x86, this patch makes it explicit
that a bad page fault is a NULL pointer dereference when the fault
address is lower than PAGE_SIZE
Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
arch/powerpc/mm/fault.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index d51cf5f4e45e..501a1eadb3e9 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -631,13 +631,16 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
switch (TRAP(regs)) {
case 0x300:
case 0x380:
- printk(KERN_ALERT "Unable to handle kernel paging request for "
- "data at address 0x%08lx\n", regs->dar);
+ pr_alert("Unable to handle kernel %s for data at address 0x%08lx\n",
+ regs->dar < PAGE_SIZE ? "NULL pointer dereference" :
+ "paging request",
+ regs->dar);
break;
case 0x400:
case 0x480:
- printk(KERN_ALERT "Unable to handle kernel paging request for "
- "instruction fetch\n");
+ pr_alert("Unable to handle kernel %s for instruction fetch\n",
+ regs->nip < PAGE_SIZE ? "NULL pointer dereference" :
+ "paging request");
break;
case 0x600:
printk(KERN_ALERT "Unable to handle kernel paging request for "
--
2.13.3
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