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To: Ethan Zhao , Xin Li , "H. Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, stable@vger.kernel.org References: From: Ethan Zhao Autocrypt: addr=haifeng.zhao@linux.intel.com; keydata= xsDNBGdk+/wBDADPlR5wKSRRgWDfH5+z+LUhBsFhuVPzmVBykmUECBwzIF/NgKeuRv2U0GT1 GpbF6bDQp6yJT8pdHj3kk612FqkHVLlMGHgrQ50KmwClPp7ml67ve8KvCnoC1hjymVj2mxnL fdfjwLHObkCCUE58+NOCSimJOaicWr39No8t2hIDkahqSy4aN2UEqL/rqUumxh8nUFjMQQSR RJtiek+goyH26YalOqGUsSfNF7oPhApD6iHETcUS6ZUlytqkenOn+epmBaTal8MA9/X2kLcr IFr1X8wdt2HbCuiGIz8I3MPIad0Il6BBx/CS0NMdk1rMiIjogtEoDRCcICJYgLDs/FjX6XQK xW27oaxtuzuc2WL/MiMTR59HLVqNT2jK/xRFHWcevNzIufeWkFLPAELMV+ODUNu2D+oGUn/6 BZ7SJ6N6MPNimjdu9bCYYbjnfbHmcy0ips9KW1ezjp2QD+huoYQQy82PaYUtIZQLztQrDBHP 86k6iwCCkg3nCJw4zokDYqkAEQEAAc0pRXRoYW4gWmhhbyA8aGFpZmVuZy56aGFvQGxpbnV4 LmludGVsLmNvbT7CwQcEEwEIADEWIQSEaSGv5l4PT4Wg1DGpx5l9v2LpDQUCZ2T7/AIbAwQL CQgHBRUICQoLBRYCAwEAAAoJEKnHmX2/YukNztAL/jkfXzpuYv5RFRqLLruRi4d8ZG4tjV2i KppIaFxMmbBjJcHZCjd2Q9DtjjPQGUeCvDMwbzq1HkuzxPgjZcsV9OVYbXm1sqsKTMm9EneL nCG0vgr1ZOpWayuKFF7zYxcF+4WM0nimCIbpKdvm/ru6nIXJl6ZsRunkWkPKLvs9E/vX5ZQ4 poN1yRLnSwi9VGV/TD1n7GnpIYiDhYVn856Xh6GoR+YCwa1EY2iSJnLj1k9inO3c5HrocZI9 xikXRsUAgParJxPK80234+TOg9HGdnJhNJ3DdyVrvOx333T0f6lute9lnscPEa2ELWHxFFAG r4E89ePIa2ylAhENaQoSjjK9z04Osx2p6BQA0uZuz+fQh9TDqh4JRKaq50uPnM+uQ0Oss2Fx 4ApWvrG13GsjGF5Qpd7vl0/gxHtztDcr5Kln6U1i5FW0MP1Z6z/JRI2WPED1dnieA6/tBqwj oiHixmpw4Zp/5gITmGoUdF1jTwXcYC7cPM/dvsCZ1AGgdmk/ic7AzQRnZPv9AQwA0rdIWu25 zLsl9GLiZHGBVZIVut88S+5kkOQ8oIih6aQ8WJPwFXzFNrkceHiN5g16Uye8jl8g58yWP8T+ zpXLaPyq6cZ1bfjmxQ7bYAWFl74rRrdots5brSSBq3K7Q3W0v1SADXVVESjGa3FyaBMilvC/ kTrx2kqqG+jcJm871Lfdij0A5gT7sLytyEJ4GsyChsEL1wZETfmU7kqRpLYX+l44rNjOh7NO DX3RqR6JagRNBUOBkvmwS5aljOMEWpb8i9Ze98AH2jjrlntDxPTc1TazE1cvSFkeVlx9NCDE A6KDe0IoPB2X4WIDr58ETsgRNq6iJJjD3r6OFEJfb/zfd3W3JTlzfBXL1s2gTkcaz6qk/EJP 2H7Uc2lEM+xBRTOp5LMEIoh2HLAqOLEfIr3sh1negsvQF5Ll1wW7/lbsSOOEnKhsAhFAQX+i rUNkU8ihMJbZpIhYqrBuomE/7ghI/hs3F1GtijdM5wG7lrCvPeEPyKHYhcp3ASUrj8DMVEw/ ABEBAAHCwPYEGAEIACAWIQSEaSGv5l4PT4Wg1DGpx5l9v2LpDQUCZ2T7/QIbDAAKCRCpx5l9 v2LpDSePC/4zDfjFDg1Bl1r1BFpYGHtFqzAX/K4YBipFNOVWPvdr0eeKYEuDc7KUrUYxbOTV I+31nLk6HQtGoRvyCl9y6vhaBvcrfxjsyKZ+llBR0pXRWT5yn33no90il1/ZHi3rwhgddQQE 7AZJ6NGWXJz0iqV72Td8iRhgIym53cykWBakIPyf2mUFcMh/BuVZNj7+zdGHwkS+B9gIL3MD GzPKkGmv7EntB0ccbFVWcxCSSyTO+uHXQlc4+0ViU/5zw49SYca8sh2HFch93JvAz+wZ3oDa eNcrHQHsGqh5c0cnu0VdZabSE0+99awYBwjJi2znKp+KQfmJJvDeSsjya2iXQMhuRq9gXKOT jK7etrO0Bba+vymPKW5+JGXoP0tQpNti8XvmpmBcVWLY4svGZLunmAjySfPp1yTjytVjWiaL ZEKDJnVrZwxK0oMB69gWc772PFn/Sz9O7WU+yHdciwn0G5KOQ0bHt+OvynLNKWVR+ANGrybN 8TCx1OJHpvWFmL4Deq8= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2025/1/18 21:50, Ethan Zhao 写道: > Hi, Xin, Peter > >   While checking the asm code of arch/x86/entry/entry_fred.o about > function fred_hwexc(), > found the code was generated as following : > > 0000000000000200 : >  200:   0f b6 87 a4 00 00 00    movzbl 0xa4(%rdi),%eax >  207:   3c 0e                   cmp    $0xe,%al /* match X86_TRAP_PF */ >  209:   75 05                   jne    210 >  20b:   e9 00 00 00 00          jmp    210 >  210:   3c 0b                   cmp    $0xb,%al >  212:   74 6a                   je     27e >  214:   77 17                   ja     22d >  216:   3c 06                   cmp    $0x6,%al >  218:   0f 84 83 00 00 00       je     2a1 >  21e:   76 29                   jbe    249 >  220:   3c 08                   cmp    $0x8,%al >  222:   74 78                   je     29c >  224:   3c 0a                   cmp    $0xa,%al >  226:   75 18                   jne    240 >  228:   e9 00 00 00 00          jmp    22d >  22d:   3c 11                   cmp    $0x11,%al >  22f:   74 66                   je     297 >  231:   76 2c                   jbe    25f >  233:   3c 13                   cmp    $0x13,%al >  235:   74 5b                   je     292 >  237:   3c 15                   cmp    $0x15,%al >  239:   75 1b                   jne    256 >  23b:   e9 00 00 00 00          jmp    240 >  240:   3c 07                   cmp    $0x7,%al >  242:   75 49                   jne    28d >  244:   e9 00 00 00 00          jmp    249 >  249:   3c 01                   cmp    $0x1,%al >  24b:   74 3b                   je     288 >  24d:   3c 05                   cmp    $0x5,%al >  24f:   75 1b                   jne    26c >  251:   e9 00 00 00 00          jmp    256 >  256:   3c 12                   cmp    $0x12,%al >  258:   75 33                   jne    28d >  25a:   e9 00 00 00 00          jmp    25f > > seems the following calling to exc_page_fault() was optimized out from > fred_hwexc() by gcc, > > if(likely(regs->fred_ss.vector==X86_TRAP_PF)) > returnexc_page_fault(regs,error_code); > > gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04) > > GNU objdump (GNU Binutils) 2.43 > > > default kernel config. > .config:CONFIG_X86_FRED=y > > my understanding, -O2 is the default kernel KBUILD_CFLAGS > So, Are there any workaround needed to make the kernel works with > default build ? > or just as Peter said in another loop, manually loading some event > bits to make the > over-smart gcc behave normally ？or fall back to -O(ption)0 ? > > Any idea, much appreciated ! > > > Thanks, > Ethan > > Rebuild the same lastest stable kernel with FRED enabled, default -O2 on RHEL 8.6, got correct result: ffffffff820a7430 : ffffffff820a7430: 55 push %rbp ffffffff820a7431: 0f b6 87 a4 00 00 00 movzbl 0xa4(%rdi),%eax ffffffff820a7438: 48 89 e5 mov %rsp,%rbp ffffffff820a743b: 3c 0e cmp $0xe,%al ffffffff820a743d: 75 0b jne ffffffff820a744a ffffffff820a743f: e8 4c 50 00 00 callq ffffffff820ac490 ffffffff820a7444: 5d pop %rbp gcc version 8.5.0 20210514 (Red Hat 8.5.0-10) (GCC) whatever CONFIG_JUMP_LABEL=y or CONFIG_JUMP_LABEL is not set. so the issue seems only about WSL ubuntu toolchain. Thanks, Ethan > > -- "firm, enduring, strong, and long-lived"