On Thu, 2019-08-22 at 14:51 +0200, Sascha Hauer wrote: > get_runtime_offset shall return the offset between the address we are > running at and the address we are linked at. This value obviously > changes when we relocate the binary. cf3b09737b tried to avoid using > R_AARCH64_RELATIVE relocations, but in fact this is exactly what the > function needs to work. Consider barebox starting at 0x10000000 > when we are linked at 0x0 then get_runtime_offset() should return > 0x10000000 before relocate_to_current_adr(), but afterwards it should > return 0x0. > > This patch brings back the previously removed "a" flag. Since gcc5 > doesn't put the values of R_AARCH64_RELATIVE fixup'd relocations > into the binary but zeroes instead, we help ourselves by basing > get_runtime_offset on an address which actually is zero. With > CONFIG_RELOCATABLE=y the binary is always linked to 0x0, so _text > is initially zero. > > Tested with gcc-5.4.0 (which was "fixed" by cf3b09737b) and gcc- > 8.2.1. > > Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> > --- > arch/arm/lib64/runtime-offset.S | 18 +++--------------- > 1 file changed, 3 insertions(+), 15 deletions(-) > > diff --git a/arch/arm/lib64/runtime-offset.S > b/arch/arm/lib64/runtime-offset.S > index 6624fdfa15..d1b8bdac3c 100644 > --- a/arch/arm/lib64/runtime-offset.S > +++ b/arch/arm/lib64/runtime-offset.S > @@ -1,31 +1,19 @@ > #include <linux/linkage.h> > #include <asm/assembler.h> > > -/* > - * The .section directive below intentionally omits "a", since that > - * appears to be the simplest way to force assembler to not generate > - * R_AARCH64_RELATIVE relocation for > - * > - * linkadr: > - * .quad get_runtime_offset > - * > - * statement below. While having that relocating was relatively > - * harmless with GCC8, builging the code with GCC5 resulted in > - * "linkaddr" being initialized to 0 causing complete boot breakdown > - */ > -.section ".text_bare_init","x" > +.section ".text_bare_init","ax" > > /* > * Get the offset between the link address and the address > * we are currently running at. > */ > ENTRY(get_runtime_offset) > -1: adr x0, 1b > +1: adr x0, _text > ldr x1, linkadr > subs x0, x0, x1 > ret > > .align 3 > linkadr: > -.quad get_runtime_offset > +.quad _text > ENDPROC(get_runtime_offset) Acked-by: Rouven Czerwinski <r.czerwinski@xxxxxxxxxxxxxx> - rcz _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
