Author: bdragon Date: Mon Dec 30 02:56:47 2019 New Revision: 356199 URL: https://svnweb.freebsd.org/changeset/base/356199
Log: [PowerPC] Fix panic when attempting to handle an HMI from an idle thread In IRC, sfs_ finally managed to get a good trace of a kernel panic that was happening when attempting to use webengine. As it turns out, we were using vtophys() from interrupt context on an idle thread in opal_hmi_handler2(). Since this involves locking the kernel pmap on PPC64 at the moment, this ended up tripping a KASSERT in mtx_lock(), which then caused a parallel panic stampede. So, avoid this by preallocating the flags variable and storing it in PCPU. Fixes "panic: mtx_lock() by idle thread 0x... on sleep mutex kernelpmap". Differential Revision: https://reviews.freebsd.org/D22962 Modified: head/sys/powerpc/include/pcpu.h head/sys/powerpc/powernv/opal_hmi.c Modified: head/sys/powerpc/include/pcpu.h ============================================================================== --- head/sys/powerpc/include/pcpu.h Mon Dec 30 02:40:55 2019 (r356198) +++ head/sys/powerpc/include/pcpu.h Mon Dec 30 02:56:47 2019 (r356199) @@ -68,7 +68,8 @@ struct pvo_entry; uint8_t slbstack[1024]; \ struct pvo_entry *qmap_pvo; \ struct mtx qmap_lock; \ - char __pad[1345]; + uint64_t opal_hmi_flags; \ + char __pad[1337]; #ifdef __powerpc64__ #define PCPU_MD_AIM_FIELDS PCPU_MD_AIM64_FIELDS Modified: head/sys/powerpc/powernv/opal_hmi.c ============================================================================== --- head/sys/powerpc/powernv/opal_hmi.c Mon Dec 30 02:40:55 2019 (r356198) +++ head/sys/powerpc/powernv/opal_hmi.c Mon Dec 30 02:56:47 2019 (r356199) @@ -84,13 +84,17 @@ opal_hmi_event_handler(void *unused, struct opal_msg * static int opal_hmi_handler2(struct trapframe *frame) { - uint64_t flags; + /* + * Use DMAP preallocated pcpu memory to handle + * the phys flags pointer. + */ + uint64_t *flags = PCPU_PTR(aim.opal_hmi_flags); int err; - flags = 0; - err = opal_call(OPAL_HANDLE_HMI2, vtophys(&flags)); + *flags = 0; + err = opal_call(OPAL_HANDLE_HMI2, DMAP_TO_PHYS((vm_offset_t)flags)); - if (flags & OPAL_HMI_FLAGS_TOD_TB_FAIL) + if (*flags & OPAL_HMI_FLAGS_TOD_TB_FAIL) panic("TOD/TB recovery failure"); if (err == OPAL_SUCCESS) _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
