From: Christophe Leroy christophe.leroy@c-s.fr
[ Upstream commit 49a502ea23bf9dec47f8f3c3960909ff409cd1bb ]
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 --- arch/powerpc/mm/fault.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 365526ee29b88..6e0ff8b600ced 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -633,21 +633,22 @@ 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("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",