On 02/17/2017 12:08 PM, Scott Wood wrote: > On Thu, 2017-02-16 at 09:11 -0600, laurentiu.tu...@nxp.com wrote: >> From: Laurentiu Tudor <laurentiu.tu...@nxp.com> >> >> On 32-bit book-e machines, hugepd_ok() does not take >> into account null hugepd values, causing this crash at boot: > > Why only 32-bit?
I wanted to get this patch out as quick as possible so i didn't had time to investigate in depth. I just tested on 64-bit that the kernel boots ok. >> diff --git a/arch/powerpc/include/asm/nohash/pgtable.h >> b/arch/powerpc/include/asm/nohash/pgtable.h >> index 0cd8a38..e5805ad 100644 >> --- a/arch/powerpc/include/asm/nohash/pgtable.h >> +++ b/arch/powerpc/include/asm/nohash/pgtable.h >> @@ -230,7 +230,7 @@ static inline int hugepd_ok(hugepd_t hpd) >> return ((hpd_val(hpd) & 0x4) != 0); >> #else >> /* We clear the top bit to indicate hugepd */ >> - return ((hpd_val(hpd) & PD_HUGE) == 0); >> + return (hpd_val(hpd) && (hpd_val(hpd) & PD_HUGE) == 0); >> #endif >> } >> > > Any reason why this can't go back to being "hpd_val(hpd) > 0"? Why was nohash > changed to begin with? I don't expect nohash (or at least fsl-book3e) will > ever have a pagetable that is not native-endian, and "> 0" is consistent with > what the TLB miss code is doing. The patch that introduced the brokenness changes "hugepd_t.pd" from "signed long" to "unsigned long" so as a consequence "> 0" was replaced with the bitwise op. --- Best Regards, Laurentiu
