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| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2020-03-31 17:32:14 +0100 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2020-07-08 15:02:37 +0100 |
| commit | 5f846c8b0dea05554a48ec5ad13874cc757a886f (patch) | |
| tree | 509d3c4ba1702ddaaab67da7a97f95643fa8d81a | |
| parent | fddbd7c0ef4960fc0a17712a95a146dd3f43de0a (diff) | |
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aarch64: fix RTLD_START for BTI
Tailcalls must use x16 or x17 for the indirect branch instruction
to be compatible with code that uses BTI c at function entries.
(Other forms of indirect branches can only land on BTI j.)
Also added a BTI c at the ELF entry point of rtld, this is not
strictly necessary since the kernel does not use indirect branch
to get there, but it seems safest once building glibc itself with
BTI is supported.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
| -rw-r--r-- | sysdeps/aarch64/dl-machine.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h index db3335e5ad..70b9ed3925 100644 --- a/sysdeps/aarch64/dl-machine.h +++ b/sysdeps/aarch64/dl-machine.h @@ -125,6 +125,8 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile) .globl _dl_start_user \n\ .type _dl_start_user, %function \n\ _start: \n\ + // bti c \n\ + hint 34 \n\ mov " PTR "0, " PTR_SP " \n\ bl _dl_start \n\ // returns user entry point in x0 \n\ @@ -178,7 +180,8 @@ _dl_start_user: \n\ adrp x0, _dl_fini \n\ add " PTR "0, " PTR "0, #:lo12:_dl_fini \n\ // jump to the user_s entry point \n\ - br x21 \n\ + mov x16, x21 \n\ + br x16 \n\ "); #define elf_machine_type_class(type) \ |