[PATCH v4] x86-64: Allocate state buffer space for RDI, RSI and RBX
H.J. Lu
hjl.tools@gmail.com
Sun Mar 17 13:02:19 GMT 2024
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.
--
H.J.
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