Copilot commented on code in PR #3696: URL: https://github.com/apache/brpc/pull/3696#discussion_r4435296810
########## src/bthread/context.cpp: ########## @@ -1012,3 +1012,247 @@ __asm ( " call _exit\n" ); #endif + +#if defined(BTHREAD_CONTEXT_PLATFORM_linux_ppc64) && defined(BTHREAD_CONTEXT_COMPILER_gcc) +__asm ( +".text\n" +".align 2\n" +".globl bthread_jump_fcontext\n" +".type bthread_jump_fcontext, @function\n" +"bthread_jump_fcontext:\n" +" addis %r2, %r12, .TOC.-bthread_jump_fcontext@ha\n" +" addi %r2, %r2, .TOC.-bthread_jump_fcontext@l\n" +" .localentry bthread_jump_fcontext, . - bthread_jump_fcontext\n" +" # reserve space on stack\n" +" subi %r1, %r1, 528\n" +" std %r14, 352(%r1)\n" +" std %r15, 360(%r1)\n" +" std %r16, 368(%r1)\n" +" std %r17, 376(%r1)\n" +" std %r18, 384(%r1)\n" +" std %r19, 392(%r1)\n" +" std %r20, 400(%r1)\n" +" std %r21, 408(%r1)\n" +" std %r22, 416(%r1)\n" +" std %r23, 424(%r1)\n" +" std %r24, 432(%r1)\n" +" std %r25, 440(%r1)\n" +" std %r26, 448(%r1)\n" +" std %r27, 456(%r1)\n" +" std %r28, 464(%r1)\n" +" std %r29, 472(%r1)\n" +" std %r30, 480(%r1)\n" +" std %r31, 488(%r1)\n" +" # save CR\n" +" mfcr %r0\n" +" std %r0, 496(%r1)\n" +" # save LR, and LR as PC\n" +" mflr %r0\n" +" std %r0, 504(%r1)\n" +" std %r0, 512(%r1)\n" +" # the fourth argument (preserve_fpu) is ignored: the compiler may keep\n" +" # any value in the non-volatile FPRs/VRs across the call\n" +" stfd %f14, 200(%r1)\n" +" stfd %f15, 208(%r1)\n" +" stfd %f16, 216(%r1)\n" +" stfd %f17, 224(%r1)\n" +" stfd %f18, 232(%r1)\n" +" stfd %f19, 240(%r1)\n" +" stfd %f20, 248(%r1)\n" +" stfd %f21, 256(%r1)\n" +" stfd %f22, 264(%r1)\n" +" stfd %f23, 272(%r1)\n" +" stfd %f24, 280(%r1)\n" +" stfd %f25, 288(%r1)\n" +" stfd %f26, 296(%r1)\n" +" stfd %f27, 304(%r1)\n" +" stfd %f28, 312(%r1)\n" +" stfd %f29, 320(%r1)\n" +" stfd %f30, 328(%r1)\n" +" stfd %f31, 336(%r1)\n" +" mffs %f0\n" +" stfd %f0, 344(%r1)\n" +#ifdef __ALTIVEC__ +" mfspr %r0, 256\n" +" std %r0, 192(%r1)\n" +" li %r11, 0\n" +" stvx %v20, %r1, %r11\n" +" li %r11, 16\n" +" stvx %v21, %r1, %r11\n" +" li %r11, 32\n" +" stvx %v22, %r1, %r11\n" +" li %r11, 48\n" +" stvx %v23, %r1, %r11\n" +" li %r11, 64\n" +" stvx %v24, %r1, %r11\n" +" li %r11, 80\n" +" stvx %v25, %r1, %r11\n" +" li %r11, 96\n" +" stvx %v26, %r1, %r11\n" +" li %r11, 112\n" +" stvx %v27, %r1, %r11\n" +" li %r11, 128\n" +" stvx %v28, %r1, %r11\n" +" li %r11, 144\n" +" stvx %v29, %r1, %r11\n" +" li %r11, 160\n" +" stvx %v30, %r1, %r11\n" +" li %r11, 176\n" +" stvx %v31, %r1, %r11\n" +#endif +" # store RSP (pointing to context-data) in R3\n" +" std %r1, 0(%r3)\n" +" # restore RSP (pointing to context-data) from R4\n" +" mr %r1, %r4\n" +#ifdef __ALTIVEC__ +" li %r11, 0\n" +" lvx %v20, %r1, %r11\n" +" li %r11, 16\n" +" lvx %v21, %r1, %r11\n" +" li %r11, 32\n" +" lvx %v22, %r1, %r11\n" +" li %r11, 48\n" +" lvx %v23, %r1, %r11\n" +" li %r11, 64\n" +" lvx %v24, %r1, %r11\n" +" li %r11, 80\n" +" lvx %v25, %r1, %r11\n" +" li %r11, 96\n" +" lvx %v26, %r1, %r11\n" +" li %r11, 112\n" +" lvx %v27, %r1, %r11\n" +" li %r11, 128\n" +" lvx %v28, %r1, %r11\n" +" li %r11, 144\n" +" lvx %v29, %r1, %r11\n" +" li %r11, 160\n" +" lvx %v30, %r1, %r11\n" +" li %r11, 176\n" +" lvx %v31, %r1, %r11\n" +" ld %r0, 192(%r1)\n" +" mtspr 256, %r0\n" +#endif +" lfd %f0, 344(%r1)\n" +" mtfsf 0xff, %f0\n" +" lfd %f14, 200(%r1)\n" +" lfd %f15, 208(%r1)\n" +" lfd %f16, 216(%r1)\n" +" lfd %f17, 224(%r1)\n" +" lfd %f18, 232(%r1)\n" +" lfd %f19, 240(%r1)\n" +" lfd %f20, 248(%r1)\n" +" lfd %f21, 256(%r1)\n" +" lfd %f22, 264(%r1)\n" +" lfd %f23, 272(%r1)\n" +" lfd %f24, 280(%r1)\n" +" lfd %f25, 288(%r1)\n" +" lfd %f26, 296(%r1)\n" +" lfd %f27, 304(%r1)\n" +" lfd %f28, 312(%r1)\n" +" lfd %f29, 320(%r1)\n" +" lfd %f30, 328(%r1)\n" +" lfd %f31, 336(%r1)\n" +" ld %r14, 352(%r1)\n" +" ld %r15, 360(%r1)\n" +" ld %r16, 368(%r1)\n" +" ld %r17, 376(%r1)\n" +" ld %r18, 384(%r1)\n" +" ld %r19, 392(%r1)\n" +" ld %r20, 400(%r1)\n" +" ld %r21, 408(%r1)\n" +" ld %r22, 416(%r1)\n" +" ld %r23, 424(%r1)\n" +" ld %r24, 432(%r1)\n" +" ld %r25, 440(%r1)\n" +" ld %r26, 448(%r1)\n" +" ld %r27, 456(%r1)\n" +" ld %r28, 464(%r1)\n" +" ld %r29, 472(%r1)\n" +" ld %r30, 480(%r1)\n" +" ld %r31, 488(%r1)\n" +" # restore CR\n" +" ld %r0, 496(%r1)\n" +" mtcr %r0\n" +" # restore LR\n" +" ld %r0, 504(%r1)\n" +" mtlr %r0\n" +" # load PC into CTR (and R12 for the callee's TOC setup)\n" +" ld %r12, 512(%r1)\n" +" mtctr %r12\n" +" # adjust stack\n" +" addi %r1, %r1, 528\n" +" # use third arg as return value after jump\n" +" # and as first arg in context function\n" +" mr %r3, %r5\n" +" # jump to context\n" +" bctr\n" +".size bthread_jump_fcontext, .-bthread_jump_fcontext\n" +".section .note.GNU-stack,\"\",%progbits\n" +); + +#endif + +#if defined(BTHREAD_CONTEXT_PLATFORM_linux_ppc64) && defined(BTHREAD_CONTEXT_COMPILER_gcc) +__asm ( +".text\n" +".align 2\n" +".globl bthread_make_fcontext\n" +".type bthread_make_fcontext, @function\n" +"bthread_make_fcontext:\n" +" addis %r2, %r12, .TOC.-bthread_make_fcontext@ha\n" +" addi %r2, %r2, .TOC.-bthread_make_fcontext@l\n" Review Comment: This entry path also overwrites the ELFv2 nonvolatile TOC pointer r2 and returns with `blr` without restoring the caller's value. A caller in a different shared object can therefore use the wrong TOC immediately after `bthread_make_fcontext` returns. Preserve the caller's r2, or defer setting r2 until the new context's finish/callee entry requires it. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
