Date: Sat, 17 Feb 2024 19:22:44 GMT From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 5d24ae53b622 - stable/13 - rdmsr_safe/wrmsr_safe: handle pcb_onfault nesting Message-ID: <202402171922.41HJMist000880@gitrepo.freebsd.org>
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The branch stable/13 has been updated by avg: URL: https://cgit.FreeBSD.org/src/commit/?id=5d24ae53b622507410d6befc5e3b8a7911991175 commit 5d24ae53b622507410d6befc5e3b8a7911991175 Author: Andriy Gapon <avg@FreeBSD.org> AuthorDate: 2024-01-30 06:45:01 +0000 Commit: Andriy Gapon <avg@FreeBSD.org> CommitDate: 2024-02-17 19:22:09 +0000 rdmsr_safe/wrmsr_safe: handle pcb_onfault nesting rdmsr_safe and wrmsr_safe can be called while pcb_onfault is already set, so the functions are modified to preserve the handler rather than resetting it before returning. One case where that happens is when AMD microcode update routine is executed on a stack where copyin / copyout was already active. Here is a sample panic message from a crash caused by resetting the handler: <118>Updating CPU Microcode... Fatal trap 12: page fault while in kernel mode cpuid = 3; apic id = 03 fault virtual address = 0x11ed0de6000 fault code = supervisor write data, page not present instruction pointer = 0x20:0xffffffff80c2df03 stack pointer = 0x28:0xfffffe01ce4a4c70 frame pointer = 0x28:0xfffffe01ce4a4c70 code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, long 1, def32 0, gran 1 processor eflags = interrupt enabled, resume, IOPL = 0 current process = 117 (logger) trap number = 12 panic: page fault cpuid = 3 time = 1681462027 KDB: stack backtrace: db_trace_self_wrapper() at 0xffffffff80615deb = db_trace_self_wrapper+0x2b/frame 0xfffffe01ce4a4830 kdb_backtrace() at 0xffffffff80943c77 = kdb_backtrace+0x37/frame 0xfffffe01ce4a48e0 vpanic() at 0xffffffff808f5fe5 = vpanic+0x185/frame 0xfffffe01ce4a4940 panic() at 0xffffffff808f5da3 = panic+0x43/frame 0xfffffe01ce4a49a0 trap_fatal() at 0xffffffff80c31849 = trap_fatal+0x379/frame 0xfffffe01ce4a4a00 trap_pfault() at 0xffffffff80c318b5 = trap_pfault+0x65/frame 0xfffffe01ce4a4a60 trap() at 0xffffffff80c30f5f = trap+0x29f/frame 0xfffffe01ce4a4b80 trap_check() at 0xffffffff80c31c29 = trap_check+0x29/frame 0xfffffe01ce4a4ba0 calltrap() at 0xffffffff80c07fd8 = calltrap+0x8/frame 0xfffffe01ce4a4ba0 --- trap 0xc, rip = 0xffffffff80c2df03, rsp = 0xfffffe01ce4a4c70, rbp = 0xfffffe01ce4a4c70 --- copyout_nosmap_std() at 0xffffffff80c2df03 = copyout_nosmap_std+0x63/frame 0xfffffe01ce4a4c70 uiomove_faultflag() at 0xffffffff8095f0d5 = uiomove_faultflag+0xe5/frame 0xfffffe01ce4a4cb0 uiomove() at 0xffffffff8095efeb = uiomove+0xb/frame 0xfffffe01ce4a4cc0 pipe_read() at 0xffffffff80968860 = pipe_read+0x230/frame 0xfffffe01ce4a4d30 dofileread() at 0xffffffff809653cb = dofileread+0x8b/frame 0xfffffe01ce4a4d80 sys_read() at 0xffffffff80964fa0 = sys_read+0xc0/frame 0xfffffe01ce4a4df0 amd64_syscall() at 0xffffffff80c3221a = amd64_syscall+0x18a/frame 0xfffffe01ce4a4f30 fast_syscall_common() at 0xffffffff80c088eb = fast_syscall_common+0xf8/frame 0xfffffe01ce4a4f30 --- syscall (3, FreeBSD ELF64, read), rip = 0x11ece41cfaa, rsp = 0x11ecbec4908, rbp = 0x11ecbec4920 --- Uptime: 41s And another one: Fatal trap 12: page fault while in kernel mode cpuid = 4; apic id = 04 fault virtual address = 0x800a22000 fault code = supervisor write data, page not present instruction pointer = 0x20:0xffffffff80b2c7ca stack pointer = 0x28:0xfffffe01c55b5480 frame pointer = 0x28:0xfffffe01c55b5480 code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, long 1, def32 0, gran 1 processor eflags = interrupt enabled, resume, IOPL = 0 current process = 68418 (pfctl) trap number = 12 panic: page fault cpuid = 4 time = 1625184463 KDB: stack backtrace: db_trace_self_wrapper() at 0xffffffff805c1e8b = db_trace_self_wrapper+0x2b/frame 0xfffffe01c55b5040 kdb_backtrace() at 0xffffffff808874b7 = kdb_backtrace+0x37/frame 0xfffffe01c55b50f0 vpanic() at 0xffffffff808449d8 = vpanic+0x188/frame 0xfffffe01c55b5150 panic() at 0xffffffff808445f3 = panic+0x43/frame 0xfffffe01c55b51b0 trap_fatal() at 0xffffffff80b300a5 = trap_fatal+0x375/frame 0xfffffe01c55b5210 trap_pfault() at 0xffffffff80b30180 = trap_pfault+0x80/frame 0xfffffe01c55b5280 trap() at 0xffffffff80b2f729 = trap+0x289/frame 0xfffffe01c55b5390 trap_check() at 0xffffffff80b304d9 = trap_check+0x29/frame 0xfffffe01c55b53b0 calltrap() at 0xffffffff80b0bb28 = calltrap+0x8/frame 0xfffffe01c55b53b0 --- trap 0xc, rip = 0xffffffff80b2c7ca, rsp = 0xfffffe01c55b5480, rbp = 0xfffffe01c55b5480 --- copyout_nosmap_std() at 0xffffffff80b2c7ca = copyout_nosmap_std+0x15a/frame 0xfffffe01c55b5480 pfioctl() at 0xffffffff85539358 = pfioctl+0x4d28/frame 0xfffffe01c55b5940 devfs_ioctl() at 0xffffffff807176cf = devfs_ioctl+0xcf/frame 0xfffffe01c55b59a0 VOP_IOCTL_APV() at 0xffffffff80bb26e2 = VOP_IOCTL_APV+0x92/frame 0xfffffe01c55b59c0 VOP_IOCTL() at 0xffffffff80928014 = VOP_IOCTL+0x34/frame 0xfffffe01c55b5a10 vn_ioctl() at 0xffffffff80923330 = vn_ioctl+0xc0/frame 0xfffffe01c55b5b00 devfs_ioctl_f() at 0xffffffff80717bbe = devfs_ioctl_f+0x1e/frame 0xfffffe01c55b5b20 fo_ioctl() at 0xffffffff808abc6b = fo_ioctl+0xb/frame 0xfffffe01c55b5b30 kern_ioctl() at 0xffffffff808abc01 = kern_ioctl+0x1d1/frame 0xfffffe01c55b5b80 sys_ioctl() at 0xffffffff808ab982 = sys_ioctl+0x132/frame 0xfffffe01c55b5c50 syscallenter() at 0xffffffff80b30cc9 = syscallenter+0x159/frame 0xfffffe01c55b5ca0 amd64_syscall() at 0xffffffff80b309a5 = amd64_syscall+0x15/frame 0xfffffe01c55b5d30 fast_syscall_common() at 0xffffffff80b0c44e = fast_syscall_common+0xf8/frame 0xfffffe01c55b5d30 PR: 276426 Reviewed by: kib, markj MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D43639 (cherry picked from commit 486b265a8fb6b2aad37f2819fa04feacf8184d53) --- sys/amd64/amd64/support.S | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S index 936065a78879..dd269138c23f 100644 --- a/sys/amd64/amd64/support.S +++ b/sys/amd64/amd64/support.S @@ -1533,6 +1533,7 @@ ENTRY(rdmsr_safe) /* int rdmsr_safe(u_int msr, uint64_t *data) */ PUSH_FRAME_POINTER movq PCPU(CURPCB),%r8 + movq PCB_ONFAULT(%r8),%r9 movq $msr_onfault,PCB_ONFAULT(%r8) movl %edi,%ecx rdmsr /* Read MSR pointed by %ecx. Returns @@ -1541,8 +1542,8 @@ ENTRY(rdmsr_safe) movl %eax,%eax /* zero-extend %eax -> %rax */ orq %rdx,%rax movq %rax,(%rsi) - xorq %rax,%rax - movq %rax,PCB_ONFAULT(%r8) + movq %r9,PCB_ONFAULT(%r8) + xorl %eax,%eax POP_FRAME_POINTER ret @@ -1554,6 +1555,7 @@ ENTRY(wrmsr_safe) /* int wrmsr_safe(u_int msr, uint64_t data) */ PUSH_FRAME_POINTER movq PCPU(CURPCB),%r8 + movq PCB_ONFAULT(%r8),%r9 movq $msr_onfault,PCB_ONFAULT(%r8) movl %edi,%ecx movl %esi,%eax @@ -1561,8 +1563,8 @@ ENTRY(wrmsr_safe) movl %esi,%edx wrmsr /* Write MSR pointed by %ecx. Accepts hi byte in edx, lo in %eax. */ - xorq %rax,%rax - movq %rax,PCB_ONFAULT(%r8) + movq %r9,PCB_ONFAULT(%r8) + xorl %eax,%eax POP_FRAME_POINTER ret @@ -1571,7 +1573,7 @@ ENTRY(wrmsr_safe) */ ALIGN_TEXT msr_onfault: - movq $0,PCB_ONFAULT(%r8) + movq %r9,PCB_ONFAULT(%r8) movl $EFAULT,%eax POP_FRAME_POINTER ret
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