diff options
Diffstat (limited to 'contrib/syslinux-4.02/com32/lib/syslinux/shuffle_rm.c')
| -rw-r--r-- | contrib/syslinux-4.02/com32/lib/syslinux/shuffle_rm.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/com32/lib/syslinux/shuffle_rm.c b/contrib/syslinux-4.02/com32/lib/syslinux/shuffle_rm.c new file mode 100644 index 0000000..a7d16d6 --- /dev/null +++ b/contrib/syslinux-4.02/com32/lib/syslinux/shuffle_rm.c @@ -0,0 +1,171 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2007-2009 H. Peter Anvin - All Rights Reserved + * Copyright 2009 Intel Corporation; author: H. Peter Anvin + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, + * copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom + * the Software is furnished to do so, subject to the following + * conditions: + * + * The above copyright notice and this permission notice shall + * be included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES + * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, + * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + * ----------------------------------------------------------------------- */ + +/* + * shuffle_rm.c + * + * Shuffle and boot to protected mode code + */ + +#include <stdlib.h> +#include <inttypes.h> +#include <com32.h> +#include <string.h> +#include <syslinux/movebits.h> +#include <syslinux/bootrm.h> + +enum gpr_index { R_AX, R_CX, R_DX, R_BX, R_SP, R_BP, R_SI, R_DI }; +enum seg_index { R_ES, R_CS, R_SS, R_DS, R_FS, R_GS }; + +#define ST8(P,V) \ + do { \ + uint8_t *_p = (void *)(P); \ + *_p++ = (V); \ + (P) = (void *)_p; \ + } while (0); +#define ST16(P,V) \ + do { \ + uint16_t *_p = (void *)(P); \ + *_p++ = (V); \ + (P) = (void *)_p; \ + } while (0) +#define ST32(P,V) \ + do { \ + uint32_t *_p = (void *)(P); \ + *_p++ = (V); \ + (P) = (void *)_p; \ + } while (0) + +#define MOV_TO_SEG(P,S,R) \ + ST16(P, 0xc08e + ((R) << 8) + ((S) << 11)) +#define MOV_TO_R16(P,R,V) \ + do { \ + ST8(P, 0xb8 + (R)); \ + ST16(P, V); \ + } while (0) +#define MOV_TO_R32(P,R,V) \ + do { \ + ST16(P, 0xb866 + ((R) << 8)); \ + ST32(P, V); \ + } while (0) + +int syslinux_shuffle_boot_rm(struct syslinux_movelist *fraglist, + struct syslinux_memmap *memmap, + uint16_t bootflags, struct syslinux_rm_regs *regs) +{ + const struct syslinux_rm_regs_alt { + uint16_t seg[6]; + uint32_t gpr[8]; + uint32_t csip; + bool sti; + } *rp; + int i, rv; + uint8_t handoff_code[8 + 5 * 5 + 8 * 6 + 1 + 5], *p; + uint16_t off; + struct syslinux_memmap *tmap; + addr_t regstub, stublen; + /* Assign GPRs for each sreg, don't use AX and SP */ + static const uint8_t gpr_for_seg[6] = + { R_CX, R_DX, R_BX, R_BP, R_SI, R_DI }; + + tmap = syslinux_target_memmap(fraglist, memmap); + if (!tmap) + return -1; + + /* + * Search for a good place to put the real-mode register stub. + * We prefer it as low as possible above 0x800. KVM barfs horribly + * if we're not aligned to a paragraph boundary, so set the alignment + * appropriately. + */ + regstub = 0x800; + stublen = sizeof handoff_code; + rv = syslinux_memmap_find(tmap, SMT_FREE, ®stub, &stublen, 16); + + if (rv || (regstub > 0x100000 - sizeof handoff_code)) { + /* + * Uh-oh. This isn't real-mode accessible memory. + * It might be possible to do something insane here like + * putting the stub in the IRQ vectors, or in the 0x5xx segment. + * This code tries the 0x510-0x7ff range and hopes for the best. + */ + regstub = 0x510; /* Try the 0x5xx segment... */ + stublen = sizeof handoff_code; + rv = syslinux_memmap_find(tmap, SMT_FREE, ®stub, &stublen, 16); + + if (!rv && (regstub > 0x100000 - sizeof handoff_code)) + rv = -1; /* No acceptable memory found */ + } + + syslinux_free_memmap(tmap); + if (rv) + return -1; + + /* Build register-setting stub */ + p = handoff_code; + rp = (const struct syslinux_rm_regs_alt *)regs; + + /* Set up GPRs with segment registers - don't use AX */ + for (i = 0; i < 6; i++) { + if (i != R_CS) + MOV_TO_R16(p, gpr_for_seg[i], rp->seg[i]); + } + + /* Actual transition to real mode */ + ST32(p, 0xeac0220f); /* MOV CR0,EAX; JMP FAR */ + off = (p - handoff_code) + 4; + ST16(p, off); /* Offset */ + ST16(p, regstub >> 4); /* Segment */ + + /* Load SS and ESP immediately */ + MOV_TO_SEG(p, R_SS, R_BX); + MOV_TO_R32(p, R_SP, rp->gpr[R_SP]); + + /* Load the other segments */ + MOV_TO_SEG(p, R_ES, R_CX); + MOV_TO_SEG(p, R_DS, R_BP); + MOV_TO_SEG(p, R_FS, R_SI); + MOV_TO_SEG(p, R_GS, R_DI); + + for (i = 0; i < 8; i++) { + if (i != R_SP) + MOV_TO_R32(p, i, rp->gpr[i]); + } + + ST8(p, rp->sti ? 0xfb : 0xfa); /* STI/CLI */ + + ST8(p, 0xea); /* JMP FAR */ + ST32(p, rp->csip); + + /* Add register-setting stub to shuffle list */ + if (syslinux_add_movelist(&fraglist, regstub, (addr_t) handoff_code, + sizeof handoff_code)) + return -1; + + return syslinux_do_shuffle(fraglist, memmap, regstub, 0, bootflags); +} |