Currently the 'stackleak_cleanup' pass deleting a CALL insn is executed after the 'reload' pass. That allows gcc to do some weird optimization in function prologues and epilogues, which are generated later [1]. Let's avoid that by registering the 'stackleak_cleanup' pass before the '*free_cfg' pass. It's the moment when the stack frame size is already final, function prologues and epilogues are generated, and the machine-dependent code transformations are not done. [1] https://www.openwall.com/lists/kernel-hardening/2018/11/23/2
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| @@ -363,10 +363,12 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, · 362 unmodified lines | |||
| 363 | PASS_POS_INSERT_BEFORE); | 363 | PASS_POS_INSERT_BEFORE); |
| 364 | 364 | ||
| 365 | /* | 365 | /* |
| 366 | * The stackleak_cleanup pass should be executed after the | 366 | * The stackleak_cleanup pass should be executed before the "*free_cfg" |
| 367 | * "reload" pass, when the stack frame size is final. | 367 | * pass. It's the moment when the stack frame size is already final, |
| 368 | * function prologues and epilogues are generated, and the | ||
| 369 | * machine-dependent code transformations are not done. | ||
| 368 | */ | 370 | */ |
| 369 | PASS_INFO(stackleak_cleanup, "reload", 1, PASS_POS_INSERT_AFTER); | 371 | PASS_INFO(stackleak_cleanup, "*free_cfg", 1, PASS_POS_INSERT_BEFORE); |
| 370 | 372 | ||
| 371 | if (!plugin_default_version_check(version, &gcc_version)) { | 373 | if (!plugin_default_version_check(version, &gcc_version)) { |
| 372 | error(G_("incompatible gcc/plugin versions")); | 374 | error(G_("incompatible gcc/plugin versions")); |