On qemu riscv64, the program below causes "panic: pmap_l2_to_l3: PA out of range, PA: 0x0" on an INVARIANTS kernel, and a kernel page fault without INVARIANTS. The immediate problem seems to be that the l2 PTE that pmap_extract() finds is all zeroes, but pmap_l2_to_l3() assumes it contains a valid physical address. #include <sys/ioctl.h> #include <unistd.h> #include <string.h> #include <fcntl.h> #include <sys/memrange.h> int main() { int fd = open("/dev/mem", 2); struct mem_extract m; memset(&m, 0, sizeof(m)); m.me_vaddr = 0x80000000; ioctl(fd, MEM_EXTRACT_PADDR, &m); } # uname -a FreeBSD 14.0-CURRENT FreeBSD 14.0-CURRENT #40 main-n250928-b8170f38ccc7-dirty: Mon Aug 29 13:09:55 EDT 2022 rtm@xxx:/usr/obj/usr/rtm/symbsd/src/riscv.riscv64/sys/RTM riscv # cc x.c # ./a.out panic: Fatal page fault at 0xffffffc000618a18: 0xffffffcf80000000 panic() at panic+0x2a page_fault_handler() at page_fault_handler+0x1d6 do_trap_supervisor() at do_trap_supervisor+0x76 cpu_exception_handler_supervisor() at cpu_exception_handler_supervisor+0x70 --- exception 13, tval = 0xffffffcf80000000 pmap_extract() at pmap_extract+0x64 memioctl() at memioctl+0x78 devfs_ioctl() at devfs_ioctl+0xbe VOP_IOCTL_APV() at VOP_IOCTL_APV+0x30 VOP_IOCTL() at VOP_IOCTL+0x36 vn_ioctl() at vn_ioctl+0xba devfs_ioctl_f() at devfs_ioctl_f+0x20 fo_ioctl() at fo_ioctl+0xa kern_ioctl() at kern_ioctl+0x242 sys_ioctl() at sys_ioctl+0x120 syscallenter() at syscallenter+0xec ecall_handler() at ecall_handler+0x18 do_trap_user() at do_trap_user+0xea cpu_exception_handler_user() at cpu_exception_handler_user+0x72
A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=ec21f85ab5f03a803884cc7bafa88621c613f4ca commit ec21f85ab5f03a803884cc7bafa88621c613f4ca Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2022-09-29 17:07:26 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2022-09-29 17:11:26 +0000 riscv: Handle invalid L2 entries in pmap_extract() While here, eliminate a single-use local variable. PR: 266103 Reviewed by: mhorne MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D36395 sys/riscv/riscv/pmap.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-)
A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=4539de92bce9afef8a041a0c6b6a1a078a49fe71 commit 4539de92bce9afef8a041a0c6b6a1a078a49fe71 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2022-09-29 17:07:26 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2022-10-13 00:44:03 +0000 riscv: Handle invalid L2 entries in pmap_extract() While here, eliminate a single-use local variable. PR: 266103 Reviewed by: mhorne (cherry picked from commit ec21f85ab5f03a803884cc7bafa88621c613f4ca) sys/riscv/riscv/pmap.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-)