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Kernel: Fix detecting in what ring a crash happened

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The ring is determined based on the CS register. This fixes crashes
being handled as ring 3 crashes even though EIP/CS clearly showed
that the crash happened in the kernel.
This commit is contained in:
Tom 2020-09-10 09:29:09 -06:00 • committed by Andreas Kling
parent 0f9be82826
commit 19ffd9d677
1 changed files with 5 additions and 4 deletions
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9
Kernel/Arch/i386/CPU.cpp
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@ -122,8 +122,8 @@ static void dump(const RegisterState& regs)
{
u16 ss;
u32 esp;
auto process = Process::current();
if (!process || process->is_ring0()) {
if (!(regs.cs & 3)) {
ss = regs.ss;
esp = regs.esp;
} else {
@ -149,6 +149,7 @@ static void dump(const RegisterState& regs)
: "=a"(cr4));
klog() << "cr0=" << String::format("%08x", cr0) << " cr2=" << String::format("%08x", cr2) << " cr3=" << String::format("%08x", cr3) << " cr4=" << String::format("%08x", cr4);
auto process = Process::current();
if (process && process->validate_read((void*)regs.eip, 8)) {
SmapDisabler disabler;
u8* codeptr = (u8*)regs.eip;
@ -168,10 +169,10 @@ void handle_crash(RegisterState& regs, const char* description, int signal, bool
// make sure we switch back to the right page tables.
MM.enter_process_paging_scope(*process);
klog() << "CRASH: CPU #" << Processor::current().id() << " " << description << ". Ring " << (process->is_ring0() ? 0 : 3) << ".";
klog() << "CRASH: CPU #" << Processor::current().id() << " " << description << ". Ring " << (regs.cs & 3) << ".";
dump(regs);
if (process->is_ring0()) {
if (!(regs.cs & 3)) {
klog() << "Crash in ring 0 :(";
dump_backtrace();
Processor::halt();