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https://github.com/ipxe/ipxe
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a3b4d6328c
On a 64-bit CPU, any modification of a register by 32-bit or 16-bit code will destroy the invisible upper 32 bits of the corresponding 64-bit register. For example: a 32-bit "pushl %eax" followed by a "popl %eax" will zero the upper half of %rax. This differs from the treatment of upper halves of 32-bit registers by 16-bit code: a "pushw %ax" followed by a "popw %ax" will leave the upper 16 bits of %eax unmodified. Inline assembly generated using REAL_CODE() or PHYS_CODE() will therefore have to preserve the upper halves of all registers, to avoid clobbering registers that gcc expects to be preserved. Output operands from REAL_CODE() and PHYS_CODE() assembly may therefore contain undefined values in the upper 32 bits. Fix by using explicit variable widths (e.g. uint32_t) for non-discarded output operands, to ensure that undefined values in the upper 32 bits of 64-bit registers are ignored. Signed-off-by: Michael Brown <mcb30@ipxe.org>
124 lines
3.5 KiB
C
124 lines
3.5 KiB
C
/*
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* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <stdint.h>
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#include <ipxe/pci.h>
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#include <realmode.h>
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/** @file
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*
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* PCI configuration space access via PCI BIOS
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*
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*/
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/**
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* Determine number of PCI buses within system
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*
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* @ret num_bus Number of buses
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*/
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static int pcibios_num_bus ( void ) {
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int discard_a, discard_D;
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uint8_t max_bus;
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/* We issue this call using flat real mode, to work around a
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* bug in some HP BIOSes.
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*/
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__asm__ __volatile__ ( REAL_CODE ( "call flatten_real_mode\n\t"
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"stc\n\t"
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"int $0x1a\n\t"
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"jnc 1f\n\t"
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"xorw %%cx, %%cx\n\t"
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"\n1:\n\t" )
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: "=c" ( max_bus ), "=a" ( discard_a ),
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"=D" ( discard_D )
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: "a" ( PCIBIOS_INSTALLATION_CHECK >> 16 ),
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"D" ( 0 )
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: "ebx", "edx" );
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return ( max_bus + 1 );
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}
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/**
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* Read configuration space via PCI BIOS
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*
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* @v pci PCI device
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* @v command PCI BIOS command
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* @v value Value read
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* @ret rc Return status code
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*/
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int pcibios_read ( struct pci_device *pci, uint32_t command, uint32_t *value ){
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int discard_b, discard_D;
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uint16_t status;
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__asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
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"int $0x1a\n\t"
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"jnc 1f\n\t"
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"xorl %%eax, %%eax\n\t"
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"decl %%eax\n\t"
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"movl %%eax, %%ecx\n\t"
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"\n1:\n\t" )
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: "=a" ( status ), "=b" ( discard_b ),
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"=c" ( *value ), "=D" ( discard_D )
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: "a" ( command >> 16 ), "D" ( command ),
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"b" ( pci->busdevfn )
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: "edx" );
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return ( status >> 8 );
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}
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/**
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* Write configuration space via PCI BIOS
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*
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* @v pci PCI device
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* @v command PCI BIOS command
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* @v value Value to be written
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* @ret rc Return status code
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*/
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int pcibios_write ( struct pci_device *pci, uint32_t command, uint32_t value ){
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int discard_b, discard_c, discard_D;
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uint16_t status;
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__asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
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"int $0x1a\n\t"
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"jnc 1f\n\t"
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"movb $0xff, %%ah\n\t"
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"\n1:\n\t" )
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: "=a" ( status ), "=b" ( discard_b ),
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"=c" ( discard_c ), "=D" ( discard_D )
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: "a" ( command >> 16 ), "D" ( command ),
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"b" ( pci->busdevfn ), "c" ( value )
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: "edx" );
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return ( status >> 8 );
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}
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PROVIDE_PCIAPI ( pcbios, pci_num_bus, pcibios_num_bus );
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PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_byte );
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PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_word );
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PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_dword );
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PROVIDE_PCIAPI_INLINE ( pcbios, pci_write_config_byte );
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PROVIDE_PCIAPI_INLINE ( pcbios, pci_write_config_word );
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PROVIDE_PCIAPI_INLINE ( pcbios, pci_write_config_dword );
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