On Sat, Jun 09, 2018 at 01:00:08PM -0700, Palmer Dabbelt wrote: > On Fri, 08 Jun 2018 17:13:12 PDT (-0700), luc.vanoostenr...@gmail.com wrote: > > I tried it and ... the preprocessed asm is as expected: > > .globl __asm_copy_to_user ; .balign 4 ; __asm_copy_to_user: > > .globl __asm_copy_from_user ; .balign 4 ; __asm_copy_from_user: > > > > > > li t6, 0x00040000 > > csrs sstatus, t6 > > ... > > > > But the nm -S returns different sizes for them: > > 0000000000000004 000000000000006c T __asm_copy_from_user > > 0000000000000002 000000000000006e T __asm_copy_to_user > > > > and the object code is: > > 0000000000000000 <__asm_copy_to_user-0x2>: > > 0: 0001 nop > > > > 0000000000000002 <__asm_copy_to_user>: > > 2: 0001 nop > > > > 0000000000000004 <__asm_copy_from_user>: > > 4: 00040fb7 lui t6,0x40 > > 8: 100fa073 csrs sstatus,t6 > > ... > > > > Why these unnneded nops? > > Is this a known problem of my toolchain (I use a plain gcc 7.3 + > > binutils 2.29, both configured as riscv64-none-elf)? > > > > If I remove the two ENTRY() and use instead: > > .globl __asm_copy_to_user ; __asm_copy_to_user: > > .globl __asm_copy_from_user ; __asm_copy_from_user: > > (IOW, I drop the .balign) then I get the expected result. > > But well, this seems unrelated to the double ENTRY. > > > > I can't test it more for now because I've some link errors (which, > > I understand are probably solved in the riscv tree of binutils). > > > > I'll send you the patch anyway since, as far as I understand the changes > > specific to this copy_to/from_user is OK. > > I think it's probably a bug in binutils-2.29 that should be fixed by > 2.30 -- IIRC we had some bugs that looked like this and they got > fixed, though it might be just in master (so 2.31).
I've tried binutils-2.30 and riscv-binutils-gdb, both still have the problem and master binutils-gdb doesn't compile for me. OTOH, everything is fine if I disabled CONFIG_RISCV_ISA_C. > Either way it looks innocuous WRT the patch. Indeed. With this, the RISC-V arch should be sparse clean. I'll recheck after -rc1. Cheers, -- Luc
