The .s file I have created looks like this:
#include <sys/asm_linkage.h
ENTRY(magic_1)
sethi (1), %g0
SET_SIZE(magic_1)
ENTRY(magic_2)
sethi (2), %g0
SET_SIZE(magic_2)
You need
ENTRY(foo)
retl
sethi bar, %g0
SET_SIZE(foo)
Which will execute a return from leaf routine and execute the sethi in
the delay slot before the branch is taken.
If you need to create a bunch of these, I would take a different tact,
and generate the code on-the-fly:
#include <sys/types.h>
struct simevent {
uint32_t s_retl;
uint32_t s_sethi;
};
#define RETL_VAL 0x81c3e008
#define SETHI_G0_VAL 0x01000000
#define TEMPLATE { RETL_VAL, SETHI_G0_VAL }
/*
* The low-order bits of the sethi instruction are the constant to
* set, so you can take the nop instruction and add a constant to it
* to get any sethi value you want into %g0.
*/
typedef void (*simevent_t)(void);
void trigger_simevent(int which_event)
{
simevent_t s;
struct simevent evt = TEMPLATE;
evt.s_sethi += which_event;
s = (simevent_t)&evt;
s();
}
Then in your code you just do:
trigger_simevent(1);
..
trigger_simevent(2);
This will work OK because the kernel stack is executable.
- Eric
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