On 9/21/23 14:11, Nikolay Borisov wrote:
+SYM_FUNC_START(asm_fred_entry_from_kvm)
+ push %rbp
+ mov %rsp, %rbp
use FRAME_BEGIN/FRAME_END macros to ommit this code if
CONFIG_FRAME_POINTER is disabled.
No, the previous stack pointer is used below, so the code might as well
use %rbp for that; but it must do so unconditionally.
Paolo
+
+ UNWIND_HINT_SAVE
+
+ /*
+ * Don't check the FRED stack level, the call stack leading to this
+ * helper is effectively constant and shallow (relatively speaking).
+ *
+ * Emulate the FRED-defined redzone and stack alignment.
+ */
+ sub $(FRED_CONFIG_REDZONE_AMOUNT << 6), %rsp
+ and $FRED_STACK_FRAME_RSP_MASK, %rsp
+
+ /*
+ * Start to push a FRED stack frame, which is always 64 bytes:
+ *
+ * +--------+-----------------+
+ * | Bytes | Usage |
+ * +--------+-----------------+
+ * | 63:56 | Reserved |
+ * | 55:48 | Event Data |
+ * | 47:40 | SS + Event Info |
+ * | 39:32 | RSP |
+ * | 31:24 | RFLAGS |
+ * | 23:16 | CS + Aux Info |
+ * | 15:8 | RIP |
+ * | 7:0 | Error Code |
+ * +--------+-----------------+
+ */
+ push $0 /* Reserved, must be 0 */
+ push $0 /* Event data, 0 for IRQ/NMI */
+ push %rdi /* fred_ss handed in by the caller */
+ push %rbp
^^ here
Paolo
+ pushf
+ mov $__KERNEL_CS, %rax
+ push %rax
