From: Christophe Leroy Date: Fri, 14 Dec 2018 15:23:33 +0000 (+0000) Subject: powerpc/mm: Make NULL pointer deferences explicit on bad page faults. X-Git-Tag: v4.19.88~154 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ba87ed0ad7c1ab3f3a335372be96c7fdab0edb3c;p=platform%2Fkernel%2Flinux-rpi.git powerpc/mm: Make NULL pointer deferences explicit on bad page faults. [ 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 [mpe: Avoid pr_cont()] Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin --- diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 365526e..6e0ff8b 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",