diff options
Diffstat (limited to 'sys/amd64/amd64')
| -rw-r--r-- | sys/amd64/amd64/exception.S | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S index f2339f8..220cf23 100644 --- a/sys/amd64/amd64/exception.S +++ b/sys/amd64/amd64/exception.S @@ -339,6 +339,9 @@ IDTVEC(prot) * and the new privilige level. We are still running on the old user stack * pointer. We have to juggle a few things around to find our stack etc. * swapgs gives us access to our PCPU space only. + * + * We do not support invoking this from a custom %cs or %ss (e.g. using + * entries from an LDT). */ IDTVEC(fast_syscall) swapgs @@ -380,6 +383,36 @@ IDTVEC(fast_syscall) movq %rsp,%rdi call syscall movq PCPU(CURPCB),%rax + testq $PCB_FULL_IRET,PCB_FLAGS(%rax) + jne 3f +1: /* Check for and handle AST's on return to userland. */ + cli + movq PCPU(CURTHREAD),%rax + testl $TDF_ASTPENDING | TDF_NEEDRESCHED,TD_FLAGS(%rax) + je 2f + sti + movq %rsp, %rdi + call ast + jmp 1b +2: /* Restore preserved registers. */ + MEXITCOUNT + movq TF_RDI(%rsp),%rdi /* bonus; preserve arg 1 */ + movq TF_RSI(%rsp),%rsi /* bonus: preserve arg 2 */ + movq TF_RDX(%rsp),%rdx /* return value 2 */ + movq TF_RAX(%rsp),%rax /* return value 1 */ + movq TF_RBX(%rsp),%rbx /* C preserved */ + movq TF_RBP(%rsp),%rbp /* C preserved */ + movq TF_R12(%rsp),%r12 /* C preserved */ + movq TF_R13(%rsp),%r13 /* C preserved */ + movq TF_R14(%rsp),%r14 /* C preserved */ + movq TF_R15(%rsp),%r15 /* C preserved */ + movq TF_RFLAGS(%rsp),%r11 /* original %rflags */ + movq TF_RIP(%rsp),%rcx /* original %rip */ + movq TF_RSP(%rsp),%r9 /* user stack pointer */ + movq %r9,%rsp /* original %rsp */ + swapgs + sysretq +3: /* Requested full context restore, use doreti for that. */ MEXITCOUNT jmp doreti |
