| Message ID | 07344034e9db66f4eeb850344e844ad0e366107f.1594224951.git.szabolcs.nagy@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | aarch64: Fix target libraries for BTI [PR96001] | expand |
> -----Original Message----- > From: Szabolcs Nagy <Szabolcs.Nagy@arm.com> > Sent: 08 July 2020 17:28 > To: gcc-patches@gcc.gnu.org > Cc: Richard Earnshaw <Richard.Earnshaw@arm.com>; Kyrylo Tkachov > <Kyrylo.Tkachov@arm.com> > Subject: [PATCH 5/6] aarch64: Fix BTI support in libgcc > > lse.S did not have the GNU property note markup and the BTI c > instructions that are necessary when it is built with branch > protection. > > The notes are only added when libgcc is built with branch > protection, because old linkers mishandle the note (merge > them incorrectly or emit warnings), the BTI instructions > are added unconditionally. > > Note: BTI c is only necessary at function entry if the function > may be called indirectly, currently lse functions are not called > indirectly, but BTI is added for ABI reasons e.g. to allow > linkers later to emit stub code with indirect jump. > Ok. Thanks, Kyrill > libgcc/ChangeLog: > > 2020-07-08 Szabolcs Nagy <szabolcs.nagy@arm.com> > > * config/aarch64/lse.S: Add BTI marking and related definitions, > and add BTI c to function entries. > --- > libgcc/config/aarch64/lse.S | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/libgcc/config/aarch64/lse.S b/libgcc/config/aarch64/lse.S > index 9e2acae806b..64691c601c1 100644 > --- a/libgcc/config/aarch64/lse.S > +++ b/libgcc/config/aarch64/lse.S > @@ -136,6 +136,8 @@ see the files COPYING3 and COPYING.RUNTIME > respectively. If not, see > #define tmp1 17 > #define tmp2 15 > > +#define BTI_C hint 34 > + > /* Start and end a function. */ > .macro STARTFN name > .text > @@ -145,6 +147,7 @@ see the files COPYING3 and COPYING.RUNTIME > respectively. If not, see > .type \name, %function > .cfi_startproc > \name: > + BTI_C > .endm > > .macro ENDFN name > @@ -275,6 +278,29 @@ STARTFN NAME(LDNM) > ENDFN NAME(LDNM) > #endif > > +/* GNU_PROPERTY_AARCH64_* macros from elf.h for use in asm code. */ > +#define FEATURE_1_AND 0xc0000000 > +#define FEATURE_1_BTI 1 > +#define FEATURE_1_PAC 2 > + > +/* Add a NT_GNU_PROPERTY_TYPE_0 note. */ > +#define GNU_PROPERTY(type, value) \ > + .section .note.gnu.property, "a"; \ > + .p2align 3; \ > + .word 4; \ > + .word 16; \ > + .word 5; \ > + .asciz "GNU"; \ > + .word type; \ > + .word 4; \ > + .word value; \ > + .word 0; > + > #if defined(__linux__) || defined(__FreeBSD__) > .section .note.GNU-stack, "", %progbits > + > +/* Add GNU property note if built with branch protection. */ > +# ifdef __ARM_FEATURE_BTI_DEFAULT > +GNU_PROPERTY (FEATURE_1_AND, FEATURE_1_BTI) > +# endif > #endif > -- > 2.17.1
diff --git a/libgcc/config/aarch64/lse.S b/libgcc/config/aarch64/lse.S index 9e2acae806b..64691c601c1 100644 --- a/libgcc/config/aarch64/lse.S +++ b/libgcc/config/aarch64/lse.S @@ -136,6 +136,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see #define tmp1 17 #define tmp2 15 +#define BTI_C hint 34 + /* Start and end a function. */ .macro STARTFN name .text @@ -145,6 +147,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see .type \name, %function .cfi_startproc \name: + BTI_C .endm .macro ENDFN name @@ -275,6 +278,29 @@ STARTFN NAME(LDNM) ENDFN NAME(LDNM) #endif +/* GNU_PROPERTY_AARCH64_* macros from elf.h for use in asm code. */ +#define FEATURE_1_AND 0xc0000000 +#define FEATURE_1_BTI 1 +#define FEATURE_1_PAC 2 + +/* Add a NT_GNU_PROPERTY_TYPE_0 note. */ +#define GNU_PROPERTY(type, value) \ + .section .note.gnu.property, "a"; \ + .p2align 3; \ + .word 4; \ + .word 16; \ + .word 5; \ + .asciz "GNU"; \ + .word type; \ + .word 4; \ + .word value; \ + .word 0; + #if defined(__linux__) || defined(__FreeBSD__) .section .note.GNU-stack, "", %progbits + +/* Add GNU property note if built with branch protection. */ +# ifdef __ARM_FEATURE_BTI_DEFAULT +GNU_PROPERTY (FEATURE_1_AND, FEATURE_1_BTI) +# endif #endif