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| author | Michael Brown | 2008-10-29 02:10:33 +0100 |
|---|---|---|
| committer | Michael Brown | 2008-10-29 02:16:52 +0100 |
| commit | 621101c36a61320ba965063658fde0eee94f73e0 (patch) | |
| tree | f129a65d5eac7860a20450d7f671d1a476c924ef | |
| parent | [phantom] Add CLP settings interface (diff) | |
| download | ipxe-621101c36a61320ba965063658fde0eee94f73e0.tar.gz ipxe-621101c36a61320ba965063658fde0eee94f73e0.tar.xz ipxe-621101c36a61320ba965063658fde0eee94f73e0.zip | |
[romprefix] Further sanity checks for the PCI 3 runtime segment address
This extends the sanity checks on the runtime segment address provided
in %bx, first implemented in commit 5600955.
We now allow the ROM to be placed anywhere above a000:0000 (rather
than c000:0000, as before), since this is the region allowed by the
PCI 3 spec. If the BIOS asks us to place the runtime image such that
it would overlap with the init-time image (which is explicitly
prohibited by the PCI 3 spec), then we assume that the BIOS is faulty
and ignore the provided runtime segment address.
Testing on a SuperMicro BIOS providing overlapping segment addresses
shows that ignoring the provided runtime segment address is safe to do
in these circumstances.
| -rw-r--r-- | src/arch/i386/prefix/romprefix.S | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S index 3351494b..9407e64c 100644 --- a/src/arch/i386/prefix/romprefix.S +++ b/src/arch/i386/prefix/romprefix.S @@ -190,11 +190,11 @@ init: stc movw $0xb101, %ax int $0x1a - jc 1f + jc no_pci3 cmpl $PCI_SIGNATURE, %edx - jne 1f + jne no_pci3 testb %ah, %ah - jnz 1f + jnz no_pci3 movw $init_message_pci, %si xorw %di, %di call print_message @@ -205,20 +205,33 @@ init: movb %bl, %al call print_hex_byte cmpb $3, %bh - jb 1f + jb no_pci3 /* PCI >=3.0: leave %gs as-is if sane */ movw %gs, %ax - cmpw $0xc000, %ax - jae 2f - /* PCI 3.0 with insane %gs value: print error and ignore %gs */ + cmpw $0xa000, %ax /* Insane if %gs < 0xa000 */ + jb pci3_insane + movw %cs, %bx /* Sane if %cs == %gs */ + cmpw %bx, %ax + je 1f + movzbw romheader_size, %cx /* Sane if %cs+len <= %gs */ + shlw $5, %cx + addw %cx, %bx + cmpw %bx, %ax + jae 1f + movw %cs, %bx /* Sane if %gs+len <= %cs */ + addw %cx, %ax + cmpw %bx, %ax + jbe 1f +pci3_insane: /* PCI 3.0 with insane %gs value: print error and ignore %gs */ movb $'!', %al call print_character movw %gs, %ax call print_hex_word -1: /* PCI <3.0: set %gs (runtime segment) = %cs (init-time segment) */ +no_pci3: + /* PCI <3.0: set %gs (runtime segment) = %cs (init-time segment) */ pushw %cs popw %gs -2: popl %edi +1: popl %edi popl %edx popl %ebx |