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powerpc/mm: Make NULL pointer deferences explicit on bad page faults.

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[ Upstream commit 49a502ea23 ]

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

In the mean time, this page makes all bad_page_fault() messages
shorter so that they remain on one single line. And it prefixes them
by "BUG: " so that they get easily grepped.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Avoid pr_cont()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Christophe Leroy
2018-12-14 15:23:33 +00:00
committed by Chris
parent 2e3c0ba287
commit e88ac76ccc
1 changed files with 9 additions and 8 deletions
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17
arch/powerpc/mm/fault.c
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@@ -521,21 +521,22 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
switch (regs->trap) {
case 0x300:
case 0x380:
printk(KERN_ALERT "Unable to handle kernel paging request for "
"data at address 0x%08lx\n", regs->dar);
pr_alert("BUG: %s at 0x%08lx\n",
regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" :
"Unable to handle kernel data access", regs->dar);
break;
case 0x400:
case 0x480:
printk(KERN_ALERT "Unable to handle kernel paging request for "
"instruction fetch\n");
pr_alert("BUG: Unable to handle kernel instruction fetch%s",
regs->nip < PAGE_SIZE ? " (NULL pointer?)\n" : "\n");
break;
case 0x600:
printk(KERN_ALERT "Unable to handle kernel paging request for "
"unaligned access at address 0x%08lx\n", regs->dar);
pr_alert("BUG: Unable to handle kernel unaligned access at 0x%08lx\n",
regs->dar);
break;
default:
printk(KERN_ALERT "Unable to handle kernel paging request for "
"unknown fault\n");
pr_alert("BUG: Unable to handle unknown paging fault at 0x%08lx\n",
regs->dar);
break;
}
printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",