Imbus/xv6-riscv-kernel
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Change mycpu() to use %gs.

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This commit is contained in:
Frans Kaashoek 2018-10-09 20:22:48 -04:00
parent 821ee3fc99
commit a7ca32e3a3
5 changed files with 21 additions and 6 deletions
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16
proc.c
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@ -37,16 +37,15 @@ cpuid() {
// Must be called with interrupts disabled to avoid the caller being
// rescheduled between reading lapicid and running through the loop.
struct cpu*
mycpu(void)
getmycpu(void)
{
int apicid, i;
if(readeflags()&FL_IF)
panic("mycpu called with interrupts enabled\n");
panic("getmycpu called with interrupts enabled\n");
apicid = lapicid();
// APIC IDs are not guaranteed to be contiguous. Maybe we should have
// a reverse map, or reserve a register to store &cpus[i].
// APIC IDs are not guaranteed to be contiguous.
for (i = 0; i < ncpu; ++i) {
if (cpus[i].apicid == apicid)
return &cpus[i];
@ -54,6 +53,15 @@ mycpu(void)
panic("unknown apicid\n");
}
// Return this core's cpu struct using %gs. %gs points this core's struct
// cpu. Offet 24 in struct cpu is cpu.
struct cpu*
mycpu(void) {
struct cpu *c;
asm volatile("mov %%gs:24, %0" : "=r" (c));
return c;
}
// Disable interrupts so that we are not rescheduled
// while reading proc from the cpu structure
struct proc*