fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-05-07 07:08:04 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 4

broadcom/compiler: Add explicit NOP instruction at page boundaries

Browse source 
The QPU prefetches the next instruction during shader execution.
If the shader assembly size perfectly aligns with a page boundary,
the prefetching mechanism reads past the compiled boundary,
leading to an MMU error.

This commit insert an explicit NOP instruction at the end of the shader
and increases the qpu_inst_count by one when the instruction count
exactly hits a page boundary. This ensures we don't fall off the end
of the last executable instruction page and into invalid memory.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40983>
This commit is contained in:
Daivik Bhatia 2026-04-15 19:34:10 +05:30 • committed by Marge Bot
parent 864ccf6cf5
commit a8c7a25fb1
1 changed files with 10 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
src/broadcom/compiler/vir_to_qpu.c
View file

@ -479,6 +479,16 @@ v3d_vir_to_qpu(struct v3d_compile *c, struct qpu_reg *temp_registers)
v3d_qpu_schedule_instructions(c);
/* If the shader ends exactly on a page boundary, append a trailing
* NOP so the QPU's instruction prefetcher can't read past the last
* real instruction into an unmapped page.
*/
if (c->qpu_inst_count * sizeof(*c->qpu_insts) % c->devinfo->page_size == 0) {
struct qinst *inst = vir_nop();
list_addtail(&inst->link, &vir_exit_block(c)->instructions);
c->qpu_inst_count++;
}
c->qpu_insts = rzalloc_array(c, uint64_t, c->qpu_inst_count);
int i = 0;
vir_for_each_inst_inorder(inst, c) {