/* * entry_from_vm86.c - tests kernel entries from vm86 mode * Copyright (c) 2014-2015 Andrew Lutomirski * * This exercises a few paths that need to special-case vm86 mode. * * GPL v2. */ #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static unsigned long load_addr = 0x10000; static int nerrs = 0; static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_sigaction = handler; sa.sa_flags = SA_SIGINFO | flags; sigemptyset(&sa.sa_mask); if (sigaction(sig, &sa, 0)) err(1, "sigaction"); } static void clearhandler(int sig) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_handler = SIG_DFL; sigemptyset(&sa.sa_mask); if (sigaction(sig, &sa, 0)) err(1, "sigaction"); } static sig_atomic_t got_signal; static void sighandler(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t*)ctx_void; if (ctx->uc_mcontext.gregs[REG_EFL] & X86_EFLAGS_VM || (ctx->uc_mcontext.gregs[REG_CS] & 3) != 3) { printf("[FAIL]\tSignal frame should not reflect vm86 mode\n"); nerrs++; } const char *signame; if (sig == SIGSEGV) signame = "SIGSEGV"; else if (sig == SIGILL) signame = "SIGILL"; else signame = "unexpected signal"; printf("[INFO]\t%s: FLAGS = 0x%lx, CS = 0x%hx\n", signame, (unsigned long)ctx->uc_mcontext.gregs[REG_EFL], (unsigned short)ctx->uc_mcontext.gregs[REG_CS]); got_signal = 1; } asm ( ".pushsection .rodata\n\t" ".type vmcode_bound, @object\n\t" "vmcode:\n\t" "vmcode_bound:\n\t" ".code16\n\t" "bound %ax, (2048)\n\t" "int3\n\t" "vmcode_sysenter:\n\t" "sysenter\n\t" "vmcode_syscall:\n\t" "syscall\n\t" "vmcode_sti:\n\t" "sti\n\t" "vmcode_int3:\n\t" "int3\n\t" "vmcode_int80:\n\t" "int $0x80\n\t" ".size vmcode, . - vmcode\n\t" "end_vmcode:\n\t" ".code32\n\t" ".popsection" ); extern unsigned char vmcode[], end_vmcode[]; extern unsigned char vmcode_bound[], vmcode_sysenter[], vmcode_syscall[], vmcode_sti[], vmcode_int3[], vmcode_int80[]; /* Returns false if the test was skipped. */ static bool do_test(struct vm86plus_struct *v86, unsigned long eip, unsigned int rettype, unsigned int retarg, const char *text) { long ret; printf("[RUN]\t%s from vm86 mode\n", text); v86->regs.eip = eip; ret = vm86(VM86_ENTER, v86); if (ret == -1 && (errno == ENOSYS || errno == EPERM)) { printf("[SKIP]\tvm86 %s\n", errno == ENOSYS ? "not supported" : "not allowed"); return false; } if (VM86_TYPE(ret) == VM86_INTx) { char trapname[32]; int trapno = VM86_ARG(ret); if (trapno == 13) strcpy(trapname, "GP"); else if (trapno == 5) strcpy(trapname, "BR"); else if (trapno == 14) strcpy(trapname, "PF"); else sprintf(trapname, "%d", trapno); printf("[INFO]\tExited vm86 mode due to #%s\n", trapname); } else if (VM86_TYPE(ret) == VM86_UNKNOWN) { printf("[INFO]\tExited vm86 mode due to unhandled GP fault\n"); } else if (VM86_TYPE(ret) == VM86_TRAP) { printf("[INFO]\tExited vm86 mode due to a trap (arg=%ld)\n", VM86_ARG(ret)); } else if (VM86_TYPE(ret) == VM86_SIGNAL) { printf("[INFO]\tExited vm86 mode due to a signal\n"); } else if (VM86_TYPE(ret) == VM86_STI) { printf("[INFO]\tExited vm86 mode due to STI\n"); } else { printf("[INFO]\tExited vm86 mode due to type %ld, arg %ld\n", VM86_TYPE(ret), VM86_ARG(ret)); } if (rettype == -1 || (VM86_TYPE(ret) == rettype && VM86_ARG(ret) == retarg)) { printf("[OK]\tReturned correctly\n"); } else { printf("[FAIL]\tIncorrect return reason\n"); nerrs++; } return true; } int main(void) { struct vm86plus_struct v86; unsigned char *addr = mmap((void *)load_addr, 4096, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANONYMOUS | MAP_PRIVATE, -1,0); if (addr != (unsigned char *)load_addr) err(1, "mmap"); memcpy(addr, vmcode, end_vmcode - vmcode); addr[2048] = 2; addr[2050] = 3; memset(&v86, 0, sizeof(v86)); v86.regs.cs = load_addr / 16; v86.regs.ss = load_addr / 16; v86.regs.ds = load_addr / 16; v86.regs.es = load_addr / 16; assert((v86.regs.cs & 3) == 0); /* Looks like RPL = 0 */ /* #BR -- should deliver SIG??? */ do_test(&v86, vmcode_bound - vmcode, VM86_INTx, 5, "#BR"); /* * SYSENTER -- should cause #GP or #UD depending on CPU. * Expected return type -1 means that we shouldn't validate * the vm86 return value. This will avoid problems on non-SEP * CPUs. */ sethandler(SIGILL, sighandler, 0); do_test(&v86, vmcode_sysenter - vmcode, -1, 0, "SYSENTER"); clearhandler(SIGILL); /* * SYSCALL would be a disaster in VM86 mode. Fortunately, * there is no kernel that both enables SYSCALL and sets * EFER.SCE, so it's #UD on all systems. But vm86 is * buggy (or has a "feature"), so the SIGILL will actually * be delivered. */ sethandler(SIGILL, sighandler, 0); do_test(&v86, vmcode_syscall - vmcode, VM86_SIGNAL, 0, "SYSCALL"); clearhandler(SIGILL); /* STI with VIP set */ v86.regs.eflags |= X86_EFLAGS_VIP; v86.regs.eflags &= ~X86_EFLAGS_IF; do_test(&v86, vmcode_sti - vmcode, VM86_STI, 0, "STI with VIP set"); /* INT3 -- should cause #BP */ do_test(&v86, vmcode_int3 - vmcode, VM86_TRAP, 3, "INT3"); /* INT80 -- should exit with "INTx 0x80" */ v86.regs.eax = (unsigned int)-1; do_test(&v86, vmcode_int80 - vmcode, VM86_INTx, 0x80, "int80"); /* Execute a null pointer */ v86.regs.cs = 0; v86.regs.ss = 0; sethandler(SIGSEGV, sighandler, 0); got_signal = 0; if (do_test(&v86, 0, VM86_SIGNAL, 0, "Execute null pointer") && !got_signal) { printf("[FAIL]\tDid not receive SIGSEGV\n"); nerrs++; } clearhandler(SIGSEGV); /* Make sure nothing explodes if we fork. */ if (fork() > 0) return 0; return (nerrs == 0 ? 0 : 1); } 783da3b24e8c9e017ac649326f (diff)
efi/fdt: Avoid FDT manipulation after ExitBootServices()
Some AArch64 UEFI implementations disable the MMU in ExitBootServices(), after which unaligned accesses to RAM are no longer supported. Commit: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel") fixed an issue in the memory map handling of the stub FDT code, but inadvertently created an issue with such firmware, by moving some of the FDT manipulation to after the invocation of ExitBootServices(). Given that the stub's libfdt implementation uses the ordinary, accelerated string functions, which rely on hardware handling of unaligned accesses, manipulating the FDT with the MMU off may result in alignment faults. So fix the situation by moving the update_fdt_memmap() call into the callback function invoked by efi_exit_boot_services() right before it calls the ExitBootServices() UEFI service (which is arguably a better place for it anyway) Note that disabling the MMU in ExitBootServices() is not compliant with the UEFI spec, and carries great risk due to the fact that switching from cached to uncached memory accesses halfway through compiler generated code (i.e., involving a stack) can never be done in a way that is architecturally safe. Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel") Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Tested-by: Riku Voipio <riku.voipio@linaro.org> Cc: <stable@vger.kernel.org> Cc: mark.rutland@arm.com Cc: linux-efi@vger.kernel.org Cc: matt@codeblueprint.co.uk Cc: leif.lindholm@linaro.org Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'net/tipc/udp_media.h')