From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Fri, 3 Dec 2021 10:44:10 +0100
> On Thu, Dec 02, 2021 at 11:32:05PM +0100, Alexander Lobakin wrote:
> > Use the newly introduces macros to create unique separate sections
> > for (almost) every "regular" ASM function (i.e. for those which
> > aren't explicitly put into a specific one).
> > There should be no leftovers as input .text will be size-asserted
> > in the LD script generated for FG-KASLR.
>
> *groan*...
>
> Please, can't we do something like:
>
> #define SYM_PUSH_SECTION(name) \
> .if section == .text \
> .push_section .text.##name \
> .else \
> .push_section .text \
> .endif
This condition
.pushsection .text
.if section == .text
# do something
.endif
.popsection
doesn't really works. `do something` doesn't happen.
This works only when
.pushsection .text
.equ section, .text
but it's not really okayish I'd say to find all .{,push}section
occurences and replace them with a macro (which would also do .equ).
I don't really know how %S with --sectname-subst should help me as
.if %S == .text
# do something
.endif
doesn't work at all (syntax error) -- and it shouldn't, %S is
supposed to work only inside .{,push}section directives.
I could do unconditional
.pushsection %S.##name
^^^^^^ function name
but this would involve changing LDS scripts (and vmlinux.lds.h) to
let's say replace *(.noinstr.text) with *(.noinstr.text*).
So I hope there is a way to get current section name? If not, then
the last option is the least harmful I suppose.
At least not as harmful as current approach with alternative macros,
far from it lol.
>
> #define SYM_POP_SECTION() \
> .pop_section
>
> and wrap that inside the existing SYM_FUNC_START*() SYM_FUNC_END()
> macros.
Thanks,
Al
