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Kernel: Disable x86 RDTSC instruction in userspace

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It's still possible to read the TSC via the read_tsc() syscall, but we
will now clear some of the bottom bits for unprivileged users.
This commit is contained in:
Andreas Kling 2020-01-01 18:18:02 +01:00
parent dfd759f75a
commit 38f93ef13b
6 changed files with 25 additions and 1 deletions
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2
Kernel/Arch/i386/CPU.cpp
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@ -526,6 +526,7 @@ bool g_cpu_supports_pae;
bool g_cpu_supports_pge;
bool g_cpu_supports_smep;
bool g_cpu_supports_sse;
bool g_cpu_supports_tsc;
bool g_cpu_supports_umip;
void detect_cpu_features()
@ -534,6 +535,7 @@ void detect_cpu_features()
g_cpu_supports_pae = (processor_info.edx() & (1 << 6));
g_cpu_supports_pge = (processor_info.edx() & (1 << 13));
g_cpu_supports_sse = (processor_info.edx() & (1 << 25));
g_cpu_supports_tsc = (processor_info.edx() & (1 << 4));
CPUID extended_processor_info(0x80000001);
g_cpu_supports_nx = (extended_processor_info.edx() & (1 << 20));