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* [Bug middle-end/29231] need a way to produce trampolines not on the stack [not found] <bug-29231-4@http.gcc.gnu.org/bugzilla/> @ 2021-11-28 0:02 ` pinskia at gcc dot gnu.org 2024-04-03 23:24 ` pinskia at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 8+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-11-28 0:02 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Status|UNCONFIRMED |NEW Last reconfirmed| |2021-11-28 --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- . ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/29231] need a way to produce trampolines not on the stack [not found] <bug-29231-4@http.gcc.gnu.org/bugzilla/> 2021-11-28 0:02 ` [Bug middle-end/29231] need a way to produce trampolines not on the stack pinskia at gcc dot gnu.org @ 2024-04-03 23:24 ` pinskia at gcc dot gnu.org 2024-04-04 8:25 ` iains at gcc dot gnu.org 2024-04-04 10:36 ` iains at gcc dot gnu.org 3 siblings, 0 replies; 8+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-04-03 23:24 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |iains at gcc dot gnu.org --- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Most of the support was added in r14-4821-g28d8c680aaea46 . Maybe Iain can provide more information on what else is needed to be done if anything. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/29231] need a way to produce trampolines not on the stack [not found] <bug-29231-4@http.gcc.gnu.org/bugzilla/> 2021-11-28 0:02 ` [Bug middle-end/29231] need a way to produce trampolines not on the stack pinskia at gcc dot gnu.org 2024-04-03 23:24 ` pinskia at gcc dot gnu.org @ 2024-04-04 8:25 ` iains at gcc dot gnu.org 2024-04-04 10:36 ` iains at gcc dot gnu.org 3 siblings, 0 replies; 8+ messages in thread From: iains at gcc dot gnu.org @ 2024-04-04 8:25 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 Iain Sandoe <iains at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- See Also| |https://gcc.gnu.org/bugzill | |a/show_bug.cgi?id=113401 --- Comment #7 from Iain Sandoe <iains at gcc dot gnu.org> --- Current status. We have implemented (currently for hosted x86 and aarch64) a heap-based trampoline approach. for efficiency heap trampolines are allocated in tables of one page in size (no pages are allocated until the first trampoline requires one). Pages are added and subtracted as the number of trampoline tables increases/decreases. One proviso - the first allocated page is sticky (this avoids mmap/etc. churn if there are a lot of single trampolines required). Trampoline pages are per thread. The mechanism works with platforms that will not allow heap pages to be both writable and executable at the same time (the page is made temporarily r+w to make changes and then r+x for operation). For Darwin, there's a permission mode "jit" that does something similar. A new platform needs to supply the libgcc support for example : libgcc/config/aarch64/heap-trampoline.c libgcc/config/aarch64/t-heap-trampoline + a reference to this in libgcc/config.host A new platform can elect to default to heap trampolines by adding HEAP_TRAMPOLINES_INIT=1 to tm_defines in the relevant target section in gcc/config.gcc There is currently (pre gcc-14 branch) one unhandled issue which is reallocation of the last "sticky" trampoline page when a thread exits. I would say, that (within realistic implementation constraints) we could count this as fixed. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/29231] need a way to produce trampolines not on the stack [not found] <bug-29231-4@http.gcc.gnu.org/bugzilla/> ` (2 preceding siblings ...) 2024-04-04 8:25 ` iains at gcc dot gnu.org @ 2024-04-04 10:36 ` iains at gcc dot gnu.org 3 siblings, 0 replies; 8+ messages in thread From: iains at gcc dot gnu.org @ 2024-04-04 10:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=29231 --- Comment #8 from Iain Sandoe <iains at gcc dot gnu.org> --- A secondary comment - the wiring up of the built-ins that allocate/deallocate trampoline entries makes the underlying mechanism opaque to the middle end consumer. So, although the current example implementations use mmap / heap, I do not believe that there is anything preventing an implementation from choosing some alternate scheme for allocation of tables (e.g. a non-hosted impl could use a fixed allocation - presumably with a hard fail if that allocation is exceeded.) ^ permalink raw reply [flat|nested] 8+ messages in thread
* [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; 8+ 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] 8+ 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 " 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; 8+ 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] 8+ 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 " 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; 8+ 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] 8+ 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 " 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; 8+ 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] 8+ 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 " 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; 8+ 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] 8+ messages in thread
end of thread, other threads:[~2024-04-04 10:36 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2021-11-28 0:02 ` [Bug middle-end/29231] need a way to produce trampolines not on the stack pinskia at gcc dot gnu.org
2024-04-03 23:24 ` pinskia at gcc dot gnu.org
2024-04-04 8:25 ` iains at gcc dot gnu.org
2024-04-04 10:36 ` iains at gcc dot gnu.org
2006-09-25 23:21 [Bug target/29231] New: powerpc libgcc writes code to " 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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