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ahci: prevent compiler memory access misordering

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While no problems have been observed in practice yet, modern compilers
may reorder memory access operations, and that could lead to problems
with memory-mapped I/O typically done by drivers. This patch prevents
any potentially problematic reordering by the compiler in the AHCI
driver.
This commit is contained in:
David van Moolenbroek 2011-11-04 14:11:34 +01:00
parent e1d867b686
commit 5320333614
1 changed files with 9 additions and 3 deletions
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12
drivers/ahci/ahci.c
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@ -116,7 +116,7 @@
/* Host Bus Adapter (HBA) state. */
PRIVATE struct {
u32_t *base; /* base address of memory-mapped registers */
volatile u32_t *base; /* base address of memory-mapped registers */
size_t size; /* size of memory-mapped register area */
int nr_ports; /* addressable number of ports (1..NR_PORTS) */
@ -131,7 +131,7 @@ PRIVATE struct port_state {
int state; /* port state */
unsigned int flags; /* port flags */
u32_t *reg; /* memory-mapped port registers */
volatile u32_t *reg; /* memory-mapped port registers */
u8_t *mem_base; /* primary memory buffer virtual address */
phys_bytes mem_phys; /* primary memory buffer physical address */
@ -1573,6 +1573,11 @@ PRIVATE void port_issue(struct port_state *ps, int cmd, clock_t timeout)
ps->reg[AHCI_PORT_SERR] = ~0L;
ps->reg[AHCI_PORT_IS] = ~0L;
/* Make sure that the compiler does not delay any previous write
* operations until after the write to the CI register.
*/
__insn_barrier();
/* Tell the controller that a new command is ready. */
ps->reg[AHCI_PORT_CI] = (1L << cmd);
@ -1909,7 +1914,8 @@ PRIVATE void ahci_stop(void)
ahci_reset();
if ((r = vm_unmap_phys(SELF, hba_state.base, hba_state.size)) != OK)
if ((r = vm_unmap_phys(SELF, (void *) hba_state.base,
hba_state.size)) != OK)
panic("unable to unmap HBA memory: %d", r);
if ((r = sys_irqrmpolicy(&hba_state.hook_id)) != OK)