[PATCH v4] x86-64: Allocate state buffer space for RDI, RSI and RBX
H.J. Lu
hjl.tools@gmail.com
Sun Mar 17 13:04:42 GMT 2024
On Sun, Mar 17, 2024 at 6:02 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sun, Mar 17, 2024 at 5:55 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > _dl_tlsdesc_dynamic preserves RDI, RSI and RBX before realigning stack.
> > After realigning stack, it saves RCX, RDX, R8, R9, R10 and R11. Define
> > TLSDESC_CALL_REGISTER_SAVE_AREA to allocate space for RDI, RSI and RBX
> > to avoid clobbering saved RDI, RSI and RBX values on stack by xsave to
> > STATE_SAVE_OFFSET(%rsp).
> >
> > +==================+<- stack frame start aligned at 8 or 16 bytes
> > | |<- RDI
> > | |<- RSI
> > | |<- RBX
> > | |<- paddings from stack realignment of 64 bytes
> > |------------------|<- xsave buffer end aligned at 64 bytes
> > | |<-
> > | |<-
> > | |<-
> > |------------------|<- xsave buffer start at STATE_SAVE_OFFSET(%rsp)
> > | |<- 8-byte padding
> > | |<- 8-byte padding
> > | |<- R11
> > | |<- R10
> > | |<- R9
> > | |<- R8
> > | |<- RDX
> > | |<- RCX
> > +==================+<- State buffer start aligned at 64 bytes
> >
> > This fixes BZ #31501.
> > ---
> > sysdeps/x86/cpu-features.c | 11 ++--
> > sysdeps/x86/sysdep.h | 29 ++++++++++
> > sysdeps/x86_64/tst-gnu2-tls2mod1.S | 87 ++++++++++++++++++++++++++++++
> > 3 files changed, 123 insertions(+), 4 deletions(-)
> > create mode 100644 sysdeps/x86_64/tst-gnu2-tls2mod1.S
> >
> > diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> > index 4ea373dffa..3d7c2819d7 100644
> > --- a/sysdeps/x86/cpu-features.c
> > +++ b/sysdeps/x86/cpu-features.c
> > @@ -311,7 +311,7 @@ update_active (struct cpu_features *cpu_features)
> > /* NB: On AMX capable processors, ebx always includes AMX
> > states. */
> > unsigned int xsave_state_full_size
> > - = ALIGN_UP (ebx + STATE_SAVE_OFFSET, 64);
> > + = ALIGN_UP (ebx + TLSDESC_CALL_REGISTER_SAVE_AREA, 64);
> >
> > cpu_features->xsave_state_size
> > = xsave_state_full_size;
> > @@ -401,8 +401,10 @@ update_active (struct cpu_features *cpu_features)
> > unsigned int amx_size
> > = (xstate_amx_comp_offsets[31]
> > + xstate_amx_comp_sizes[31]);
> > - amx_size = ALIGN_UP (amx_size + STATE_SAVE_OFFSET,
> > - 64);
> > + amx_size
> > + = ALIGN_UP ((amx_size
> > + + TLSDESC_CALL_REGISTER_SAVE_AREA),
> > + 64);
> > /* Set xsave_state_full_size to the compact AMX
> > state size for XSAVEC. NB: xsave_state_full_size
> > is only used in _dl_tlsdesc_dynamic_xsave and
> > @@ -410,7 +412,8 @@ update_active (struct cpu_features *cpu_features)
> > cpu_features->xsave_state_full_size = amx_size;
> > #endif
> > cpu_features->xsave_state_size
> > - = ALIGN_UP (size + STATE_SAVE_OFFSET, 64);
> > + = ALIGN_UP (size + TLSDESC_CALL_REGISTER_SAVE_AREA,
> > + 64);
> > CPU_FEATURE_SET (cpu_features, XSAVEC);
> > }
> > }
> > diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
> > index db8e576e91..46fcd27345 100644
> > --- a/sysdeps/x86/sysdep.h
> > +++ b/sysdeps/x86/sysdep.h
> > @@ -46,6 +46,34 @@
> > red-zone into account. */
> > # define STATE_SAVE_OFFSET (8 * 7 + 8)
> >
> > +/* _dl_tlsdesc_dynamic preserves RDI, RSI and RBX before realigning
> > + stack. After realigning stack, it saves RCX, RDX, R8, R9, R10 and
> > + R11. Allocate space for RDI, RSI and RBX to avoid clobbering saved
> > + RDI, RSI and RBX values on stack by xsave.
> > +
> > + +==================+<- stack frame start aligned at 8 or 16 bytes
> > + | |<- RDI
> > + | |<- RSI
> > + | |<- RBX
> > + | |<- paddings from stack realignment of 64 bytes
> > + |------------------|<- xsave buffer end aligned at 64 bytes
> > + | |<-
> > + | |<-
> > + | |<-
> > + |------------------|<- xsave buffer start at STATE_SAVE_OFFSET(%rsp)
> > + | |<- 8-byte padding
> > + | |<- 8-byte padding
> > + | |<- R11
> > + | |<- R10
> > + | |<- R9
> > + | |<- R8
> > + | |<- RDX
> > + | |<- RCX
> > + +==================+<- State buffer start aligned at 64 bytes
> > +
> > +*/
> > +# define TLSDESC_CALL_REGISTER_SAVE_AREA (STATE_SAVE_OFFSET + 24)
> > +
> > /* Save SSE, AVX, AVX512, mask, bound and APX registers. Bound and APX
> > registers are mutually exclusive. */
> > # define STATE_SAVE_MASK \
> > @@ -68,6 +96,7 @@
> > /* Offset for fxsave/xsave area used by _dl_tlsdesc_dynamic. Since i386
> > doesn't have red-zone, use 0 here. */
> > # define STATE_SAVE_OFFSET 0
> > +# define TLSDESC_CALL_REGISTER_SAVE_AREA 0
> >
> > /* Save SSE, AVX, AXV512, mask and bound registers. */
> > # define STATE_SAVE_MASK \
> > diff --git a/sysdeps/x86_64/tst-gnu2-tls2mod1.S b/sysdeps/x86_64/tst-gnu2-tls2mod1.S
> > new file mode 100644
> > index 0000000000..449ddd5c9d
> > --- /dev/null
> > +++ b/sysdeps/x86_64/tst-gnu2-tls2mod1.S
> > @@ -0,0 +1,87 @@
> > +/* Check if TLSDESC relocation preserves %rdi, %rsi and %rbx.
> > + Copyright (C) 2024 Free Software Foundation, Inc.
> > + This file is part of the GNU C Library.
> > +
> > + The GNU C Library is free software; you can redistribute it and/or
> > + modify it under the terms of the GNU Lesser General Public
> > + License as published by the Free Software Foundation; either
> > + version 2.1 of the License, or (at your option) any later version.
> > +
> > + The GNU C Library is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > + Lesser General Public License for more details.
> > +
> > + You should have received a copy of the GNU Lesser General Public
> > + License along with the GNU C Library; if not, see
> > + <http://www.gnu.org/licenses/>. */
> > +
> > +#include <sysdep.h>
> > +
> > +/* On AVX512 machines, OFFSET == 104 caused _dl_tlsdesc_dynamic_xsavec
> > + to clobber %rdi, %rsi and %rbx. On Intel AVX CPUs, the state size
> > + is 960 bytes and this test didn't fail. It may be due to the unused
> > + last 128 bytes. On AMD AVX CPUs, the state size is 832 bytes and
> > + this test might fail without the fix. */
> > +#ifndef OFFSET
> > +# define OFFSET 104
> > +#endif
> > +
> > + .text
> > + .p2align 4
> > + .globl apply_tls
> > + .type apply_tls, @function
> > +apply_tls:
> > + cfi_startproc
> > + _CET_ENDBR
> > + pushq %rbp
> > + cfi_def_cfa_offset (16)
> > + cfi_offset (6, -16)
> > + movdqu (%RDI_LP), %xmm0
> > + lea tls_var1@TLSDESC(%rip), %RAX_LP
> > + mov %RSP_LP, %RBP_LP
> > + cfi_def_cfa_register (6)
> > + /* Align stack to 64 bytes. */
> > + and $-64, %RSP_LP
> > + sub $OFFSET, %RSP_LP
> > + pushq %rbx
> > + /* Set %ebx to 0xbadbeef. */
> > + movl $0xbadbeef, %ebx
> > + movl $0xbadbeef, %esi
> > + movq %rdi, saved_rdi(%rip)
> > + movq %rsi, saved_rsi(%rip)
> > + call *tls_var1@TLSCALL(%RAX_LP)
> > + /* Check if _dl_tlsdesc_dynamic preserves %rdi, %rsi and %rbx. */
> > + cmpq saved_rdi(%rip), %rdi
> > + jne L(hlt)
> > + cmpq saved_rsi(%rip), %rsi
> > + jne L(hlt)
> > + cmpl $0xbadbeef, %ebx
> > + jne L(hlt)
> > + add %fs:0, %RAX_LP
> > + movups %xmm0, 32(%RAX_LP)
> > + movdqu 16(%RDI_LP), %xmm1
> > + mov %RAX_LP, %RBX_LP
> > + movups %xmm1, 48(%RAX_LP)
> > + lea 32(%RBX_LP), %RAX_LP
> > + pop %rbx
> > + leave
> > + cfi_def_cfa (7, 8)
> > + ret
> > +L(hlt):
> > + hlt
> > + cfi_endproc
> > + .size apply_tls, .-apply_tls
> > + .hidden tls_var1
> > + .globl tls_var1
> > + .section .tbss,"awT",@nobits
> > + .align 16
> > + .type tls_var1, @object
> > + .size tls_var1, 3200
> > +tls_var1:
> > + .zero 3200
> > + .local saved_rdi
> > + .comm saved_rdi,8,8
> > + .local saved_rsi
> > + .comm saved_rsi,8,8
> > + .section .note.GNU-stack,"",@progbits
> > --
> > 2.44.0
> >
>
> I need to adjust assembly codes.
>
Never mind. Not needed.
--
H.J.
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