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x86/traps: Cleanup do_general_protection()
Hoist the user_mode() case up because it is less code and can be dealt with up-front like the other special cases UMIP and vm86. This saves an indentation level for the kernel-mode #GP case and allows to "unfold" the code more so that it is more readable. No functional changes. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Jann Horn <jannh@google.com> Cc: x86@kernel.org
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@ -567,7 +567,10 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
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dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
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{
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char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
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enum kernel_gp_hint hint = GP_NO_HINT;
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struct task_struct *tsk;
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unsigned long gp_addr;
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int ret;
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RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
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cond_local_irq_enable(regs);
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@ -584,58 +587,56 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
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}
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tsk = current;
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if (!user_mode(regs)) {
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enum kernel_gp_hint hint = GP_NO_HINT;
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unsigned long gp_addr;
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if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
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return;
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if (user_mode(regs)) {
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tsk->thread.error_code = error_code;
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tsk->thread.trap_nr = X86_TRAP_GP;
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/*
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* To be potentially processing a kprobe fault and to
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* trust the result from kprobe_running(), we have to
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* be non-preemptible.
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*/
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if (!preemptible() && kprobe_running() &&
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kprobe_fault_handler(regs, X86_TRAP_GP))
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return;
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show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
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force_sig(SIGSEGV);
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if (notify_die(DIE_GPF, desc, regs, error_code,
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X86_TRAP_GP, SIGSEGV) == NOTIFY_STOP)
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return;
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if (error_code)
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snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
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else
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hint = get_kernel_gp_address(regs, &gp_addr);
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if (hint != GP_NO_HINT)
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snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",
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(hint == GP_NON_CANONICAL) ?
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"probably for non-canonical address" :
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"maybe for address",
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gp_addr);
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/*
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* KASAN is interested only in the non-canonical case, clear it
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* otherwise.
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*/
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if (hint != GP_NON_CANONICAL)
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gp_addr = 0;
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die_addr(desc, regs, error_code, gp_addr);
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return;
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}
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if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
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return;
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tsk->thread.error_code = error_code;
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tsk->thread.trap_nr = X86_TRAP_GP;
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show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
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/*
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* To be potentially processing a kprobe fault and to trust the result
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* from kprobe_running(), we have to be non-preemptible.
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*/
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if (!preemptible() &&
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kprobe_running() &&
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kprobe_fault_handler(regs, X86_TRAP_GP))
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return;
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ret = notify_die(DIE_GPF, desc, regs, error_code, X86_TRAP_GP, SIGSEGV);
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if (ret == NOTIFY_STOP)
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return;
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if (error_code)
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snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
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else
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hint = get_kernel_gp_address(regs, &gp_addr);
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if (hint != GP_NO_HINT)
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snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",
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(hint == GP_NON_CANONICAL) ? "probably for non-canonical address"
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: "maybe for address",
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gp_addr);
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/*
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* KASAN is interested only in the non-canonical case, clear it
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* otherwise.
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*/
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if (hint != GP_NON_CANONICAL)
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gp_addr = 0;
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die_addr(desc, regs, error_code, gp_addr);
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force_sig(SIGSEGV);
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}
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NOKPROBE_SYMBOL(do_general_protection);
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