diff options
| author | Ian Moffett <ian@osmora.org> | 2025-08-12 23:46:11 -0400 |
|---|---|---|
| committer | Ian Moffett <ian@osmora.org> | 2025-08-12 23:52:47 -0400 |
| commit | 83372e621621cd8509adc164599b212406970576 (patch) | |
| tree | b2d52c685b0e084e191a3b64a9e4283f2f3e8c91 | |
| parent | eb4ec8d4b0d5d596c67dc2baf935df30e27fbb71 (diff) | |
kernel/amd64: conf: Add CPU_UMIP config option
This commit adds the CPU_UMIP kconf(9) option to allow the user to
configure whether or not the kernel should enable the CR4.UMIP bit.
It is recommended to keep this to "yes" as user applications should
not be able to execute the SGDT, SIDT, SLDT, SMSW or STR instructions
at all for security reasons.
Signed-off-by: Ian Moffett <ian@osmora.org>
| -rw-r--r-- | sys/arch/amd64/amd64/machdep.c | 11 | ||||
| -rw-r--r-- | sys/arch/amd64/conf/GENERIC | 1 |
2 files changed, 12 insertions, 0 deletions
diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c index 7720620..6408ad3 100644 --- a/sys/arch/amd64/amd64/machdep.c +++ b/sys/arch/amd64/amd64/machdep.c @@ -74,6 +74,12 @@ #define CPU_SMEP 0 #endif +#if defined(__CPU_UMIP) +#define CPU_UMIP __CPU_UMIP +#else +#define CPU_UMIP 0 +#endif + int ibrs_enable(void); int simd_init(void); void syscall_isr(void); @@ -355,6 +361,11 @@ cpu_enable_umip(void) struct cpu_info *ci = this_cpu(); uint64_t cr4; + if (!CPU_UMIP) { + pr_trace_bsp("UMIP not configured\n"); + return; + } + if (ISSET(ci->feat, CPU_FEAT_UMIP)) { cr4 = amd64_read_cr4(); cr4 |= CR4_UMIP; diff --git a/sys/arch/amd64/conf/GENERIC b/sys/arch/amd64/conf/GENERIC index 9411999..6bf3af5 100644 --- a/sys/arch/amd64/conf/GENERIC +++ b/sys/arch/amd64/conf/GENERIC @@ -7,6 +7,7 @@ // option SPECTRE_IBRS no // Enable the IBRS CPU feature option SERIAL_DEBUG yes // Enable kmsg serial logging +option CPU_UMIP yes // Enable User-mode Instruction Prevention option USER_KMSG no // Show kmsg in user consoles option USER_TSC no // Enable 'rdtsc' in user mode option CPU_SMEP yes // Supervisor Memory Exec Protection |