From: "Chao Li" <lichao@loongson.cn>
To: Liming Gao <gaoliming@byosoft.com.cn>,
Bob Feng <bob.c.feng@intel.com>,
Yuwei Chen <yuwei.chen@intel.com>
Cc: devel@edk2.groups.io
Subject: [edk2-devel] About EDK2 supports Self Modifying Code
Date: Tue, 15 Aug 2023 11:06:08 +0800 [thread overview]
Message-ID: <22642530-3177-d5d9-426a-d5a68ebfe8c6@loongson.cn> (raw)
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Hi Liming, Bob and Yuwei
There is a need that some code wants to supports Self-Modification,
because some program behavior may not be determined during compilation,
and I think this demand may be very popular.
The permise of Self-Modification is that the section has executable and
writable permissions. Adding a new section and giving it executable and
writable permissions is a better way, and the 'pragma seg_code' is
recognized in Microsoft VS compiler but GCC doesn't. If use the GCC as
the compiler, the '.section name flags' of GNU GAS are acceptable.
But there is a problem, if converting from elf to efi, the user-defined
section with W+X or A+W+X will be droped, Elf64Convert.c will scan the
file section permission of elf, if the section is A+X, it will be
classified into the .text section, if the section is A+W , then it will
be classified into the .data section, if the section is A+W+X or W+X,
then it will be droped(Elf64Convert.c, line 272 to 325).
That is:
If using the VS compiler, the user-defined with executable and writable
sections may be perserved, but GCC elf to efi conversion may not.
Hope hearback from you and discuss the necessity of
SMC(Slef-Modifying-Code) and how to implement it.
Thanks,
Chao
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next reply other threads:[~2023-08-15 3:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-15 3:06 Chao Li [this message]
2023-08-15 4:57 ` [edk2-devel] About EDK2 supports Self Modifying Code Andrew Fish via groups.io
2023-08-15 8:20 ` Chao Li
2023-08-15 8:28 ` Ard Biesheuvel
2023-08-15 8:54 ` Chao Li
2023-08-15 15:05 ` Andrew Fish via groups.io
2023-08-15 15:39 ` Pedro Falcato
2023-08-15 16:30 ` Andrew Fish via groups.io
2023-08-15 18:48 ` Ard Biesheuvel
2023-08-15 21:26 ` Andrew Fish via groups.io
2023-08-17 3:38 ` Chao Li
2023-08-15 15:35 ` Pedro Falcato
2023-08-17 2:30 ` Chao Li
2023-08-17 19:53 ` Michael D Kinney
2023-08-17 20:55 ` Andrew Fish via groups.io
2023-08-19 2:18 ` Chao Li
2023-08-19 4:29 ` Michael D Kinney
2023-08-25 4:02 ` Chao Li
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