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ae531041c7
Add 3 command-line options to generate lfence for load, indirect near branch and ret to help mitigate: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00334.html http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-0551 1. -mlfence-after-load=[no|yes]: -mlfence-after-load=yes generates lfence after load instructions. 2. -mlfence-before-indirect-branch=[none|all|memory|register]: a. -mlfence-before-indirect-branch=all generates lfence before indirect near branches via register and a warning before indirect near branches via memory. b. -mlfence-before-indirect-branch=memory issue a warning before indirect near branches via memory. c. -mlfence-before-indirect-branch=register generates lfence before indirect near branches via register. Note that lfence won't be generated before indirect near branches via register with -mlfence-after-load=yes since lfence will be generated after loading branch target register. 3. -mlfence-before-ret=[none|or|not] a. -mlfence-before-ret=or generates or with lfence before ret. b. -mlfence-before-ret=not generates not with lfence before ret. A warning will be issued and lfence won't be generated before indirect near branch and ret if the previous item is a prefix or a constant directive, which may be used to hardcode an instruction, since there is no clear instruction boundary. * config/tc-i386.c (lfence_after_load): New. (lfence_before_indirect_branch_kind): New. (lfence_before_indirect_branch): New. (lfence_before_ret_kind): New. (lfence_before_ret): New. (last_insn): New. (load_insn_p): New. (insert_lfence_after): New. (insert_lfence_before): New. (md_assemble): Call insert_lfence_before and insert_lfence_after. Set last_insn. (OPTION_MLFENCE_AFTER_LOAD): New. (OPTION_MLFENCE_BEFORE_INDIRECT_BRANCH): New. (OPTION_MLFENCE_BEFORE_RET): New. (md_longopts): Add -mlfence-after-load=, -mlfence-before-indirect-branch= and -mlfence-before-ret=. (md_parse_option): Handle -mlfence-after-load=, -mlfence-before-indirect-branch= and -mlfence-before-ret=. (md_show_usage): Display -mlfence-after-load=, -mlfence-before-indirect-branch= and -mlfence-before-ret=. (i386_cons_align): New. * config/tc-i386.h (i386_cons_align): New. (md_cons_align): New. * doc/c-i386.texi: Document -mlfence-after-load=, -mlfence-before-indirect-branch= and -mlfence-before-ret=. |
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| .. | ||
| all.texi | ||
| as.texi | ||
| c-aarch64.texi | ||
| c-alpha.texi | ||
| c-arc.texi | ||
| c-arm.texi | ||
| c-avr.texi | ||
| c-bfin.texi | ||
| c-bpf.texi | ||
| c-cr16.texi | ||
| c-cris.texi | ||
| c-csky.texi | ||
| c-d10v.texi | ||
| c-d30v.texi | ||
| c-epiphany.texi | ||
| c-h8300.texi | ||
| c-hppa.texi | ||
| c-i386.texi | ||
| c-ia64.texi | ||
| c-ip2k.texi | ||
| c-lm32.texi | ||
| c-m32c.texi | ||
| c-m32r.texi | ||
| c-m68hc11.texi | ||
| c-m68k.texi | ||
| c-metag.texi | ||
| c-microblaze.texi | ||
| c-mips.texi | ||
| c-mmix.texi | ||
| c-msp430.texi | ||
| c-mt.texi | ||
| c-nds32.texi | ||
| c-nios2.texi | ||
| c-ns32k.texi | ||
| c-or1k.texi | ||
| c-pdp11.texi | ||
| c-pj.texi | ||
| c-ppc.texi | ||
| c-pru.texi | ||
| c-riscv.texi | ||
| c-rl78.texi | ||
| c-rx.texi | ||
| c-s12z.texi | ||
| c-s390.texi | ||
| c-score.texi | ||
| c-sh.texi | ||
| c-sparc.texi | ||
| c-tic6x.texi | ||
| c-tic54x.texi | ||
| c-tilegx.texi | ||
| c-tilepro.texi | ||
| c-v850.texi | ||
| c-vax.texi | ||
| c-visium.texi | ||
| c-wasm32.texi | ||
| c-xc16x.texi | ||
| c-xgate.texi | ||
| c-xstormy16.texi | ||
| c-xtensa.texi | ||
| c-z8k.texi | ||
| c-z80.texi | ||
| fdl.texi | ||
| h8.texi | ||
| internals.texi | ||
| Makefile.am | ||
| Makefile.in | ||