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efef7f184f
For historic reasons there are some TSC-related functions in the
<asm/msr.h> header, even though there's an <asm/tsc.h> header.
To facilitate the relocation of rdtsc{,_ordered}() from <asm/msr.h>
to <asm/tsc.h> and to eventually eliminate the inclusion of
<asm/msr.h> in <asm/tsc.h>, add an explicit <asm/msr.h> dependency
to the source files that reference definitions from <asm/msr.h>.
[ mingo: Clarified the changelog. ]
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20250501054241.1245648-1-xin@zytor.com
94 lines
3.1 KiB
C
94 lines
3.1 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/msr.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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DEFINE_PER_CPU(unsigned long, fred_rsp0);
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EXPORT_PER_CPU_SYMBOL(fred_rsp0);
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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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/*
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* If a kernel event is delivered before a CPU goes to user level for
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* the first time, its SS is NULL thus NULL is pushed into the SS field
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* of the FRED stack frame. But before ERETS is executed, the CPU may
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* context switch to another task and go to user level. Then when the
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* CPU comes back to kernel mode, SS is changed to __KERNEL_DS. Later
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* when ERETS is executed to return from the kernel event handler, a #GP
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* fault is generated because SS doesn't match the SS saved in the FRED
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* stack frame.
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*
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* Initialize SS to __KERNEL_DS when enabling FRED to avoid such #GPs.
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*/
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loadsegment(ss, __KERNEL_DS);
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wrmsrq(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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wrmsrq(MSR_IA32_FRED_STKLVLS, 0);
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/*
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* Ater a CPU offline/online cycle, the FRED RSP0 MSR should be
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* resynchronized with its per-CPU cache.
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*/
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wrmsrq(MSR_IA32_FRED_RSP0, __this_cpu_read(fred_rsp0));
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wrmsrq(MSR_IA32_FRED_RSP1, 0);
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wrmsrq(MSR_IA32_FRED_RSP2, 0);
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wrmsrq(MSR_IA32_FRED_RSP3, 0);
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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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/* Must be called after setup_cpu_entry_areas() */
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void cpu_init_fred_rsps(void)
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{
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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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wrmsrq(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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wrmsrq(MSR_IA32_FRED_RSP1, __this_cpu_ist_top_va(DB));
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wrmsrq(MSR_IA32_FRED_RSP2, __this_cpu_ist_top_va(NMI));
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wrmsrq(MSR_IA32_FRED_RSP3, __this_cpu_ist_top_va(DF));
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}
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