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cdd99dd873
Add cpu_init_fred_exceptions() to: - Set FRED entrypoints for events happening in ring 0 and 3. - Specify the stack level for IRQs occurred ring 0. - Specify dedicated event stacks for #DB/NMI/#MCE/#DF. - Enable FRED and invalidtes IDT. - Force 32-bit system calls to use "int $0x80" only. Add fred_complete_exception_setup() to: - Initialize system_vectors as done for IDT systems. - Set unused sysvec_table entries to fred_handle_spurious_interrupt(). Co-developed-by: Xin Li <xin3.li@intel.com> Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Xin Li <xin3.li@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Shan Kang <shan.kang@intel.com> Link: https://lore.kernel.org/r/20231205105030.8698-35-xin3.li@intel.com
60 lines
2 KiB
C
60 lines
2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/kernel.h>
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#include <asm/desc.h>
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#include <asm/fred.h>
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#include <asm/tlbflush.h>
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#include <asm/traps.h>
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/* #DB in the kernel would imply the use of a kernel debugger. */
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#define FRED_DB_STACK_LEVEL 1UL
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#define FRED_NMI_STACK_LEVEL 2UL
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#define FRED_MC_STACK_LEVEL 2UL
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/*
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* #DF is the highest level because a #DF means "something went wrong
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* *while delivering an exception*." The number of cases for which that
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* can happen with FRED is drastically reduced and basically amounts to
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* "the stack you pointed me to is broken." Thus, always change stacks
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* on #DF, which means it should be at the highest level.
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*/
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#define FRED_DF_STACK_LEVEL 3UL
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#define FRED_STKLVL(vector, lvl) ((lvl) << (2 * (vector)))
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void cpu_init_fred_exceptions(void)
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{
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/* When FRED is enabled by default, remove this log message */
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pr_info("Initialize FRED on CPU%d\n", smp_processor_id());
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wrmsrl(MSR_IA32_FRED_CONFIG,
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/* Reserve for CALL emulation */
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FRED_CONFIG_REDZONE |
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FRED_CONFIG_INT_STKLVL(0) |
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FRED_CONFIG_ENTRYPOINT(asm_fred_entrypoint_user));
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/*
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* The purpose of separate stacks for NMI, #DB and #MC *in the kernel*
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* (remember that user space faults are always taken on stack level 0)
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* is to avoid overflowing the kernel stack.
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*/
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wrmsrl(MSR_IA32_FRED_STKLVLS,
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FRED_STKLVL(X86_TRAP_DB, FRED_DB_STACK_LEVEL) |
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FRED_STKLVL(X86_TRAP_NMI, FRED_NMI_STACK_LEVEL) |
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FRED_STKLVL(X86_TRAP_MC, FRED_MC_STACK_LEVEL) |
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FRED_STKLVL(X86_TRAP_DF, FRED_DF_STACK_LEVEL));
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/* The FRED equivalents to IST stacks... */
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wrmsrl(MSR_IA32_FRED_RSP1, __this_cpu_ist_top_va(DB));
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wrmsrl(MSR_IA32_FRED_RSP2, __this_cpu_ist_top_va(NMI));
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wrmsrl(MSR_IA32_FRED_RSP3, __this_cpu_ist_top_va(DF));
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/* Enable FRED */
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cr4_set_bits(X86_CR4_FRED);
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/* Any further IDT use is a bug */
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idt_invalidate();
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/* Use int $0x80 for 32-bit system calls in FRED mode */
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setup_clear_cpu_cap(X86_FEATURE_SYSENTER32);
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setup_clear_cpu_cap(X86_FEATURE_SYSCALL32);
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}
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