arch/x86/include/asm/apm.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *  Machine specific APM BIOS functions for generic.
   4  *  Split out from apm.c by Osamu Tomita <tomita@cinet.co.jp>
   5  */
   6
   7 #ifndef _ASM_X86_MACH_DEFAULT_APM_H
   8 #define _ASM_X86_MACH_DEFAULT_APM_H
   9
  10 #include <asm/nospec-branch.h>
  11
  12 #ifdef APM_ZERO_SEGS
  13 #       define APM_DO_ZERO_SEGS \
  14                 "pushl %%ds\n\t" \
  15                 "pushl %%es\n\t" \
  16                 "xorl %%edx, %%edx\n\t" \
  17                 "mov %%dx, %%ds\n\t" \
  18                 "mov %%dx, %%es\n\t" \
  19                 "mov %%dx, %%fs\n\t" \
  20                 "mov %%dx, %%gs\n\t"
  21 #       define APM_DO_POP_SEGS \
  22                 "popl %%es\n\t" \
  23                 "popl %%ds\n\t"
  24 #else
  25 #       define APM_DO_ZERO_SEGS
  26 #       define APM_DO_POP_SEGS
  27 #endif
  28
  29 static inline void apm_bios_call_asm(u32 func, u32 ebx_in, u32 ecx_in,
  30                                         u32 *eax, u32 *ebx, u32 *ecx,
  31                                         u32 *edx, u32 *esi)
  32 {
  33         /*
  34          * N.B. We do NOT need a cld after the BIOS call
  35          * because we always save and restore the flags.
  36          */
  37         firmware_restrict_branch_speculation_start();
  38         __asm__ __volatile__(APM_DO_ZERO_SEGS
  39                 "pushl %%edi\n\t"
  40                 "pushl %%ebp\n\t"
  41                 "lcall *%%cs:apm_bios_entry\n\t"
  42                 "setc %%al\n\t"
  43                 "popl %%ebp\n\t"
  44                 "popl %%edi\n\t"
  45                 APM_DO_POP_SEGS
  46                 : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx),
  47                   "=S" (*esi)
  48                 : "a" (func), "b" (ebx_in), "c" (ecx_in)
  49                 : "memory", "cc");
  50         firmware_restrict_branch_speculation_end();
  51 }
  52
  53 static inline bool apm_bios_call_simple_asm(u32 func, u32 ebx_in,
  54                                             u32 ecx_in, u32 *eax)
  55 {
  56         int     cx, dx, si;
  57         bool    error;
  58
  59         /*
  60          * N.B. We do NOT need a cld after the BIOS call
  61          * because we always save and restore the flags.
  62          */
  63         firmware_restrict_branch_speculation_start();
  64         __asm__ __volatile__(APM_DO_ZERO_SEGS
  65                 "pushl %%edi\n\t"
  66                 "pushl %%ebp\n\t"
  67                 "lcall *%%cs:apm_bios_entry\n\t"
  68                 "setc %%bl\n\t"
  69                 "popl %%ebp\n\t"
  70                 "popl %%edi\n\t"
  71                 APM_DO_POP_SEGS
  72                 : "=a" (*eax), "=b" (error), "=c" (cx), "=d" (dx),
  73                   "=S" (si)
  74                 : "a" (func), "b" (ebx_in), "c" (ecx_in)
  75                 : "memory", "cc");
  76         firmware_restrict_branch_speculation_end();
  77         return error;
  78 }
  79
  80 #endif /* _ASM_X86_MACH_DEFAULT_APM_H */