11787 Kernel needs to be built with retpolines
11788 Kernel needs to generally use RSB stuffing
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: John Levon <john.levon@joyent.com>

*** 87,97 ****
              SCR_REG, SCR_REGB);
          CALC_TABLE_ADDR(SCR_REG, SPD_HANDLER);
          mov     %rcx, SYSCALL_REG; /* save orig return addr in syscall_reg */
          mov     SCR_REG, %rcx;  /* place new return addr in %rcx */
          mov     %gs:CPU_RTMP_R15, SCR_REG; /* restore scratch register */
!         call    *x86_md_clear           /* Flush micro-arch state */
          mov     V_SSP(SP_REG), SP_REG   /* restore user stack pointer */
          jmp     nopop_sys_syscall32_swapgs_sysretl
  9:
          retq
  SET_SIZE(XXX_brand_syscall32_callback)
--- 87,97 ----
              SCR_REG, SCR_REGB);
          CALC_TABLE_ADDR(SCR_REG, SPD_HANDLER);
          mov     %rcx, SYSCALL_REG; /* save orig return addr in syscall_reg */
          mov     SCR_REG, %rcx;  /* place new return addr in %rcx */
          mov     %gs:CPU_RTMP_R15, SCR_REG; /* restore scratch register */
!         call    x86_md_clear            /* Flush micro-arch state */
          mov     V_SSP(SP_REG), SP_REG   /* restore user stack pointer */
          jmp     nopop_sys_syscall32_swapgs_sysretl
  9:
          retq
  SET_SIZE(XXX_brand_syscall32_callback)
*** 107,117 ****
              SCR_REG, SCR_REGB);
          CALC_TABLE_ADDR(SCR_REG, SPD_HANDLER);
          mov     %rcx, SYSCALL_REG; /* save orig return addr in syscall_reg */
          mov     SCR_REG, %rcx;  /* place new return addr in %rcx */
          mov     %gs:CPU_RTMP_R15, SCR_REG; /* restore scratch register */
!         call    *x86_md_clear           /* Flush micro-arch state */
          mov     V_SSP(SP_REG), SP_REG   /* restore user stack pointer */
          jmp     nopop_sys_syscall_swapgs_sysretq
  9:
          retq
  SET_SIZE(XXX_brand_syscall_callback)
--- 107,117 ----
              SCR_REG, SCR_REGB);
          CALC_TABLE_ADDR(SCR_REG, SPD_HANDLER);
          mov     %rcx, SYSCALL_REG; /* save orig return addr in syscall_reg */
          mov     SCR_REG, %rcx;  /* place new return addr in %rcx */
          mov     %gs:CPU_RTMP_R15, SCR_REG; /* restore scratch register */
!         call    x86_md_clear            /* Flush micro-arch state */
          mov     V_SSP(SP_REG), SP_REG   /* restore user stack pointer */
          jmp     nopop_sys_syscall_swapgs_sysretq
  9:
          retq
  SET_SIZE(XXX_brand_syscall_callback)