On Fri, 14 Feb 2020 at 00:48, Philippe Mathieu-Daudé <address@hidden> wrote:
The command is 32-bit, but we are loading the 16 upper bits with
the 'get_uint16(s->scb + 2)' call.
Once shifted by 16, the command bits match the status bits:
- Command
Bit 31 ACK-CX Acknowledges that the CU completed an Action Command.
Bit 30 ACK-FR Acknowledges that the RU received a frame.
Bit 29 ACK-CNA Acknowledges that the Command Unit became not active.
Bit 28 ACK-RNR Acknowledges that the Receive Unit became not ready.
- Status
Bit 15 CX The CU finished executing a command with its I(interrupt)
bit set.
Bit 14 FR The RU finished receiving a frame.
Bit 13 CNA The Command Unit left the Active state.
Bit 12 RNR The Receive Unit left the Ready state.
Add the SCB_COMMAND_ACK_MASK definition to simplify the code.
This fixes Coverity 1419392 (CONSTANT_EXPRESSION_RESULT):
/hw/net/i82596.c: 352 in examine_scb()
346 cuc = (command >> 8) & 0x7;
347 ruc = (command >> 4) & 0x7;
348 DBG(printf("MAIN COMMAND %04x cuc %02x ruc %02x\n", command,
cuc, ruc));
349 /* and clear the scb command word */
350 set_uint16(s->scb + 2, 0);
351
>>> CID 1419392: (CONSTANT_EXPRESSION_RESULT)
>>> "command & (2147483648UL /* 1UL << 31 */)" is always 0 regardless of the
values of its operands. This occurs as the logical operand of "if".
352 if (command & BIT(31)) /* ACK-CX */
353 s->scb_status &= ~SCB_STATUS_CX;
>>> CID 1419392: (CONSTANT_EXPRESSION_RESULT)
>>> "command & (1073741824UL /* 1UL << 30 */)" is always 0 regardless of the
values of its operands. This occurs as the logical operand of "if".
354 if (command & BIT(30)) /*ACK-FR */
355 s->scb_status &= ~SCB_STATUS_FR;
>>> CID 1419392: (CONSTANT_EXPRESSION_RESULT)
>>> "command & (536870912UL /* 1UL << 29 */)" is always 0 regardless of the values
of its operands. This occurs as the logical operand of "if".
356 if (command & BIT(29)) /*ACK-CNA */
357 s->scb_status &= ~SCB_STATUS_CNA;
>>> CID 1419392: (CONSTANT_EXPRESSION_RESULT)
>>> "command & (268435456UL /* 1UL << 28 */)" is always 0 regardless of the values
of its operands. This occurs as the logical operand of "if".
358 if (command & BIT(28)) /*ACK-RNR */
359 s->scb_status &= ~SCB_STATUS_RNR;
Fixes: Covertiy CID 1419392 (commit 376b851909)
("Coverity")
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
Reviewed-by: Peter Maydell <address@hidden>
Jason, are you planning to pick this one up?