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dd84441a79
Retpoline means the kernel is safe because it has no indirect branches. But firmware isn't, so use IBRS for firmware calls if it's available. Block preemption while IBRS is set, although in practice the call sites already had to be doing that. Ignore hpwdt.c for now. It's taking spinlocks and calling into firmware code, from an NMI handler. I don't want to touch that with a bargepole. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: arjan.van.de.ven@intel.com Cc: bp@alien8.de Cc: dave.hansen@intel.com Cc: jmattson@google.com Cc: karahmed@amazon.de Cc: kvm@vger.kernel.org Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Link: http://lkml.kernel.org/r/1519037457-7643-2-git-send-email-dwmw@amazon.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
80 lines
1.9 KiB
C
80 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Machine specific APM BIOS functions for generic.
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* Split out from apm.c by Osamu Tomita <tomita@cinet.co.jp>
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*/
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#ifndef _ASM_X86_MACH_DEFAULT_APM_H
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#define _ASM_X86_MACH_DEFAULT_APM_H
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#include <asm/nospec-branch.h>
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#ifdef APM_ZERO_SEGS
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# define APM_DO_ZERO_SEGS \
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"pushl %%ds\n\t" \
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"pushl %%es\n\t" \
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"xorl %%edx, %%edx\n\t" \
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"mov %%dx, %%ds\n\t" \
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"mov %%dx, %%es\n\t" \
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"mov %%dx, %%fs\n\t" \
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"mov %%dx, %%gs\n\t"
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# define APM_DO_POP_SEGS \
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"popl %%es\n\t" \
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"popl %%ds\n\t"
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#else
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# define APM_DO_ZERO_SEGS
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# define APM_DO_POP_SEGS
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#endif
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static inline void apm_bios_call_asm(u32 func, u32 ebx_in, u32 ecx_in,
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u32 *eax, u32 *ebx, u32 *ecx,
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u32 *edx, u32 *esi)
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{
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/*
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* N.B. We do NOT need a cld after the BIOS call
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* because we always save and restore the flags.
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*/
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firmware_restrict_branch_speculation_start();
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__asm__ __volatile__(APM_DO_ZERO_SEGS
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"pushl %%edi\n\t"
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"pushl %%ebp\n\t"
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"lcall *%%cs:apm_bios_entry\n\t"
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"setc %%al\n\t"
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"popl %%ebp\n\t"
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"popl %%edi\n\t"
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APM_DO_POP_SEGS
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: "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx),
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"=S" (*esi)
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: "a" (func), "b" (ebx_in), "c" (ecx_in)
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: "memory", "cc");
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firmware_restrict_branch_speculation_end();
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}
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static inline bool apm_bios_call_simple_asm(u32 func, u32 ebx_in,
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u32 ecx_in, u32 *eax)
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{
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int cx, dx, si;
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bool error;
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/*
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* N.B. We do NOT need a cld after the BIOS call
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* because we always save and restore the flags.
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*/
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firmware_restrict_branch_speculation_start();
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__asm__ __volatile__(APM_DO_ZERO_SEGS
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"pushl %%edi\n\t"
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"pushl %%ebp\n\t"
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"lcall *%%cs:apm_bios_entry\n\t"
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"setc %%bl\n\t"
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"popl %%ebp\n\t"
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"popl %%edi\n\t"
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APM_DO_POP_SEGS
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: "=a" (*eax), "=b" (error), "=c" (cx), "=d" (dx),
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"=S" (si)
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: "a" (func), "b" (ebx_in), "c" (ecx_in)
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: "memory", "cc");
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firmware_restrict_branch_speculation_end();
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return error;
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}
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#endif /* _ASM_X86_MACH_DEFAULT_APM_H */
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