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x86/fault: Split the OOPS code out from no_context()
Not all callers of no_context() want to run exception fixups. Separate the OOPS code out from the fixup code in no_context(). Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/450f8d8eabafb83a5df349108c8e5ea83a2f939d.1612924255.git.luto@kernel.org
This commit is contained in:
Andy Lutomirski
Borislav Petkov
parent
03c81ea333
commit
2cc624b0a7
1 changed files with 77 additions and 69 deletions
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@ -655,13 +655,84 @@ static void set_signal_archinfo(unsigned long address,
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}
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static noinline void
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no_context(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, int signal, int si_code)
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page_fault_oops(struct pt_regs *regs, unsigned long error_code,
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unsigned long address)
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{
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struct task_struct *tsk = current;
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unsigned long flags;
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int sig;
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if (user_mode(regs)) {
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/*
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* Implicit kernel access from user mode? Skip the stack
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* overflow and EFI special cases.
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*/
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goto oops;
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}
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#ifdef CONFIG_VMAP_STACK
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/*
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* Stack overflow? During boot, we can fault near the initial
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* stack in the direct map, but that's not an overflow -- check
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* that we're in vmalloc space to avoid this.
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*/
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if (is_vmalloc_addr((void *)address) &&
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(((unsigned long)current->stack - 1 - address < PAGE_SIZE) ||
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address - ((unsigned long)current->stack + THREAD_SIZE) < PAGE_SIZE)) {
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unsigned long stack = __this_cpu_ist_top_va(DF) - sizeof(void *);
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/*
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* We're likely to be running with very little stack space
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* left. It's plausible that we'd hit this condition but
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* double-fault even before we get this far, in which case
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* we're fine: the double-fault handler will deal with it.
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*
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* We don't want to make it all the way into the oops code
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* and then double-fault, though, because we're likely to
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* break the console driver and lose most of the stack dump.
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*/
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asm volatile ("movq %[stack], %%rsp\n\t"
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"call handle_stack_overflow\n\t"
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"1: jmp 1b"
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: ASM_CALL_CONSTRAINT
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: "D" ("kernel stack overflow (page fault)"),
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"S" (regs), "d" (address),
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[stack] "rm" (stack));
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unreachable();
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}
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#endif
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/*
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* Buggy firmware could access regions which might page fault, try to
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* recover from such faults.
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*/
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if (IS_ENABLED(CONFIG_EFI))
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efi_recover_from_page_fault(address);
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oops:
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice:
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*/
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flags = oops_begin();
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show_fault_oops(regs, error_code, address);
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if (task_stack_end_corrupted(current))
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printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
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sig = SIGKILL;
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if (__die("Oops", regs, error_code))
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sig = 0;
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/* Executive summary in case the body of the oops scrolled away */
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printk(KERN_DEFAULT "CR2: %016lx\n", address);
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oops_end(flags, regs, sig);
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}
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static noinline void
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no_context(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, int signal, int si_code)
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{
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if (user_mode(regs)) {
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/*
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* This is an implicit supervisor-mode access from user
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@ -702,78 +773,15 @@ no_context(struct pt_regs *regs, unsigned long error_code,
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return;
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}
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#ifdef CONFIG_VMAP_STACK
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/*
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* Stack overflow? During boot, we can fault near the initial
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* stack in the direct map, but that's not an overflow -- check
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* that we're in vmalloc space to avoid this.
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*/
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if (is_vmalloc_addr((void *)address) &&
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(((unsigned long)tsk->stack - 1 - address < PAGE_SIZE) ||
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address - ((unsigned long)tsk->stack + THREAD_SIZE) < PAGE_SIZE)) {
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unsigned long stack = __this_cpu_ist_top_va(DF) - sizeof(void *);
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/*
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* We're likely to be running with very little stack space
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* left. It's plausible that we'd hit this condition but
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* double-fault even before we get this far, in which case
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* we're fine: the double-fault handler will deal with it.
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*
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* We don't want to make it all the way into the oops code
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* and then double-fault, though, because we're likely to
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* break the console driver and lose most of the stack dump.
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*/
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asm volatile ("movq %[stack], %%rsp\n\t"
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"call handle_stack_overflow\n\t"
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"1: jmp 1b"
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: ASM_CALL_CONSTRAINT
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: "D" ("kernel stack overflow (page fault)"),
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"S" (regs), "d" (address),
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[stack] "rm" (stack));
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unreachable();
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}
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#endif
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/*
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* 32-bit:
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*
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* Valid to do another page fault here, because if this fault
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* had been triggered by is_prefetch fixup_exception would have
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* handled it.
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*
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* 64-bit:
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*
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* Hall of shame of CPU/BIOS bugs.
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* AMD erratum #91 manifests as a spurious page fault on a PREFETCH
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* instruction.
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*/
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if (is_prefetch(regs, error_code, address))
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return;
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/*
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* Buggy firmware could access regions which might page fault, try to
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* recover from such faults.
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*/
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if (IS_ENABLED(CONFIG_EFI))
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efi_recover_from_page_fault(address);
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oops:
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice:
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*/
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flags = oops_begin();
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show_fault_oops(regs, error_code, address);
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if (task_stack_end_corrupted(tsk))
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printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
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sig = SIGKILL;
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if (__die("Oops", regs, error_code))
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sig = 0;
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/* Executive summary in case the body of the oops scrolled away */
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printk(KERN_DEFAULT "CR2: %016lx\n", address);
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oops_end(flags, regs, sig);
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page_fault_oops(regs, error_code, address);
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}
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/*
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