diff options
| author | iximeow <me@iximeow.net> | 2026-04-12 01:03:47 +0000 |
|---|---|---|
| committer | iximeow <me@iximeow.net> | 2026-05-25 00:59:27 +0000 |
| commit | a049351c5d512710f557ffb45ee6391fc86a3dc6 (patch) | |
| tree | 17040c4c95f9361de271fb1ad874c3a71d2b0e9d /src/protected_mode/mod.rs | |
| parent | 6c32405ca9930f393d8ca45d22df1b5a1c7c8653 (diff) | |
fix table management instructions' ({l,s}{g,i,l}dt) mem_size
these instructions, it turns out, have fixed operand size based on CPU
execution mode and regardless of prefixes. good to know!
Diffstat (limited to 'src/protected_mode/mod.rs')
| -rw-r--r-- | src/protected_mode/mod.rs | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/src/protected_mode/mod.rs b/src/protected_mode/mod.rs index 6701071..89c5dfd 100644 --- a/src/protected_mode/mod.rs +++ b/src/protected_mode/mod.rs @@ -8042,7 +8042,7 @@ fn read_operands< } else { instruction.opcode = Opcode::SGDT; instruction.operand_count = 1; - instruction.mem_size = 63; + instruction.mem_size = 6; instruction.operands[0] = read_E(words, instruction, modrm, bank, sink)?; } } else if r == 1 { @@ -8097,7 +8097,11 @@ fn read_operands< } else { instruction.opcode = Opcode::SIDT; instruction.operand_count = 1; - instruction.mem_size = 63; + // quoth SDM: + // > In non-64-bit modes, the 16-bit limit field of the register is stored in + // > the low 2 bytes of the memory location and the 32-bit base address is + // > stored in the high 4 bytes. + instruction.mem_size = 6; instruction.operands[0] = read_E(words, instruction, modrm, bank, sink)?; } } else if r == 2 { @@ -8136,7 +8140,10 @@ fn read_operands< } else { instruction.opcode = Opcode::LGDT; instruction.operand_count = 1; - instruction.mem_size = 63; + // quoth SDM: + // > In legacy or compatibility mode, the destination operand is a 6-byte + // > memory location. + instruction.mem_size = 6; instruction.operands[0] = read_E(words, instruction, modrm, bank, sink)?; } } else if r == 3 { @@ -8200,7 +8207,7 @@ fn read_operands< } else { instruction.opcode = Opcode::LIDT; instruction.operand_count = 1; - instruction.mem_size = 63; + instruction.mem_size = 6; instruction.operands[0] = read_E(words, instruction, modrm, bank, sink)?; } } else if r == 4 { |