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* [Bug target/29231] New: powerpc libgcc writes code to the stack @ 2006-09-25 23:21 debian-gcc at lists dot debian dot org 2006-09-25 23:53 ` [Bug middle-end/29231] need a way to produce trampolines not on " pinskia at gcc dot gnu dot org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: debian-gcc at lists dot debian dot org @ 2006-09-25 23:21 UTC (permalink / raw) To: gcc-bugs [forwarded from http://bugs.debian.org/382746] reported for 4.1 SVN 20060608, Matthias __trampoline_setup in /lib/libgcc_s.so.1 puts code on the stack. This contributes to insecurity on powerpc. A half-way fix is to mmap a page for this evil crud. This still violates good practice, needing the OS to allow either write+execute or a dangerous transition from write to execute. It'd be an improvement though. Doing write+execute may be better, allowing the OS to locate the page within a segment (256 MiB chunk on PowerPC) which already has executable pages. A better method would be to supply a page full of trampoline functions in libgcc. Each function would: 1. examine its own address 2. map from the page of code to a page of data 3. use that data to implement the trampoline Trampoline setup would thus involve filling in the data and choosing the matching function to use. Once libgcc stops putting code on the stack, gcc needs to mark all executables as not requiring an executable stack. -- Summary: powerpc libgcc writes code to the stack Product: gcc Version: 4.1.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: debian-gcc at lists dot debian dot org GCC target triplet: powerpc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/29231] need a way to produce trampolines not on the stack 2006-09-25 23:21 [Bug target/29231] New: powerpc libgcc writes code to the stack debian-gcc at lists dot debian dot org @ 2006-09-25 23:53 ` pinskia at gcc dot gnu dot org 2006-09-26 0:44 ` geoffk at gcc dot gnu dot org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2006-09-25 23:53 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from pinskia at gcc dot gnu dot org 2006-09-25 23:53 ------- Really there is no way to fix this without compiler help. -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement Component|target |middle-end GCC target triplet|powerpc-linux-gnu | Summary|powerpc libgcc writes code |need a way to produce |to the stack |trampolines not on the stack http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/29231] need a way to produce trampolines not on the stack 2006-09-25 23:21 [Bug target/29231] New: powerpc libgcc writes code to the stack debian-gcc at lists dot debian dot org 2006-09-25 23:53 ` [Bug middle-end/29231] need a way to produce trampolines not on " pinskia at gcc dot gnu dot org @ 2006-09-26 0:44 ` geoffk at gcc dot gnu dot org 2006-09-26 4:06 ` acahalan at gmail dot com 2009-01-01 21:25 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: geoffk at gcc dot gnu dot org @ 2006-09-26 0:44 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from geoffk at gcc dot gnu dot org 2006-09-26 00:44 ------- If you tried the page-of-functions idea, what would you do if you'd used all the functions on the page and needed another one? -- geoffk at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |patch http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/29231] need a way to produce trampolines not on the stack 2006-09-25 23:21 [Bug target/29231] New: powerpc libgcc writes code to the stack debian-gcc at lists dot debian dot org 2006-09-25 23:53 ` [Bug middle-end/29231] need a way to produce trampolines not on " pinskia at gcc dot gnu dot org 2006-09-26 0:44 ` geoffk at gcc dot gnu dot org @ 2006-09-26 4:06 ` acahalan at gmail dot com 2009-01-01 21:25 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: acahalan at gmail dot com @ 2006-09-26 4:06 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from acahalan at gmail dot com 2006-09-26 04:06 ------- (In reply to comment #2) > If you tried the page-of-functions idea, what would you do if you'd used all > the functions on the page and needed another one? > You'd do the same as if you'd used up all the stack space. The existing method doesn't handle running out of room, and I don't see why the requirements would be any different for this method. -- acahalan at gmail dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |acahalan at gmail dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/29231] need a way to produce trampolines not on the stack 2006-09-25 23:21 [Bug target/29231] New: powerpc libgcc writes code to the stack debian-gcc at lists dot debian dot org ` (2 preceding siblings ...) 2006-09-26 4:06 ` acahalan at gmail dot com @ 2009-01-01 21:25 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2009-01-01 21:25 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from pinskia at gcc dot gnu dot org 2009-01-01 21:22 ------- This is why the PowerOpen ABI is good, it does not require stack based trampolines. -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords|patch | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2009-01-01 21:25 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2006-09-25 23:21 [Bug target/29231] New: powerpc libgcc writes code to the stack debian-gcc at lists dot debian dot org 2006-09-25 23:53 ` [Bug middle-end/29231] need a way to produce trampolines not on " pinskia at gcc dot gnu dot org 2006-09-26 0:44 ` geoffk at gcc dot gnu dot org 2006-09-26 4:06 ` acahalan at gmail dot com 2009-01-01 21:25 ` pinskia at gcc dot gnu dot org
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