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e1cd82a339
In the following commit:
025768a966 x86/cpu: Use alternative to generate the TASK_SIZE_MAX constant
... we added the new task_size_max() inline, which uses X86_FEATURE_LA57,
but doesn't include <asm/cpufeatures.h> which defines the constant.
Due to the way alternatives macros work currently this doesn't get reported as an
immediate build error, only as a link error, if a .c file happens to include
<asm/page.h> first:
> ld: kernel/fork.o:(.altinstructions+0x98): undefined reference to `X86_FEATURE_LA57'
In the current upstream kernel no .c file includes <asm/page.h> before including
some other header that includes <asm/cpufeatures.h>, which is why this dependency
bug went unnoticed.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
100 lines
2.7 KiB
C
100 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_PAGE_64_H
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#define _ASM_X86_PAGE_64_H
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#include <asm/page_64_types.h>
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#ifndef __ASSEMBLY__
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#include <asm/cpufeatures.h>
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#include <asm/alternative.h>
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/* duplicated to the one in bootmem.h */
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extern unsigned long max_pfn;
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extern unsigned long phys_base;
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extern unsigned long page_offset_base;
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extern unsigned long vmalloc_base;
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extern unsigned long vmemmap_base;
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static inline unsigned long __phys_addr_nodebug(unsigned long x)
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{
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unsigned long y = x - __START_KERNEL_map;
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/* use the carry flag to determine if x was < __START_KERNEL_map */
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x = y + ((x > y) ? phys_base : (__START_KERNEL_map - PAGE_OFFSET));
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return x;
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}
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#ifdef CONFIG_DEBUG_VIRTUAL
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extern unsigned long __phys_addr(unsigned long);
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extern unsigned long __phys_addr_symbol(unsigned long);
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#else
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#define __phys_addr(x) __phys_addr_nodebug(x)
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#define __phys_addr_symbol(x) \
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((unsigned long)(x) - __START_KERNEL_map + phys_base)
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#endif
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#define __phys_reloc_hide(x) (x)
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#ifdef CONFIG_FLATMEM
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#define pfn_valid(pfn) ((pfn) < max_pfn)
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#endif
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void clear_page_orig(void *page);
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void clear_page_rep(void *page);
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void clear_page_erms(void *page);
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static inline void clear_page(void *page)
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{
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alternative_call_2(clear_page_orig,
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clear_page_rep, X86_FEATURE_REP_GOOD,
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clear_page_erms, X86_FEATURE_ERMS,
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"=D" (page),
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"0" (page)
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: "cc", "memory", "rax", "rcx");
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}
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void copy_page(void *to, void *from);
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#ifdef CONFIG_X86_5LEVEL
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/*
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* User space process size. This is the first address outside the user range.
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* There are a few constraints that determine this:
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*
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* On Intel CPUs, if a SYSCALL instruction is at the highest canonical
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* address, then that syscall will enter the kernel with a
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* non-canonical return address, and SYSRET will explode dangerously.
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* We avoid this particular problem by preventing anything
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* from being mapped at the maximum canonical address.
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*
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* On AMD CPUs in the Ryzen family, there's a nasty bug in which the
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* CPUs malfunction if they execute code from the highest canonical page.
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* They'll speculate right off the end of the canonical space, and
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* bad things happen. This is worked around in the same way as the
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* Intel problem.
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*
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* With page table isolation enabled, we map the LDT in ... [stay tuned]
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*/
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static __always_inline unsigned long task_size_max(void)
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{
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unsigned long ret;
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alternative_io("movq %[small],%0","movq %[large],%0",
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X86_FEATURE_LA57,
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"=r" (ret),
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[small] "i" ((1ul << 47)-PAGE_SIZE),
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[large] "i" ((1ul << 56)-PAGE_SIZE));
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return ret;
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}
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#endif /* CONFIG_X86_5LEVEL */
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#endif /* !__ASSEMBLY__ */
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#ifdef CONFIG_X86_VSYSCALL_EMULATION
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# define __HAVE_ARCH_GATE_AREA 1
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#endif
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#endif /* _ASM_X86_PAGE_64_H */
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