diff --git a/linux-user/elfload.c b/linux-user/elfload.c index b0723071e2..46f73a4166 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -305,12 +305,27 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs, const CPUX86State *en (*regs)[15] = tswapreg(env->regs[R_ESP]); (*regs)[16] = tswapreg(env->segs[R_SS].selector & 0xffff); } -#endif + +/* + * i386 is the only target which supplies AT_SYSINFO for the vdso. + * All others only supply AT_SYSINFO_EHDR. + */ +#define DLINFO_ARCH_ITEMS (vdso_info != NULL) +#define ARCH_DLINFO \ + do { \ + if (vdso_info) { \ + NEW_AUX_ENT(AT_SYSINFO, vdso_info->entry); \ + } \ + } while (0) + +#define VDSO_HEADER "vdso.c.inc" + +#endif /* TARGET_X86_64 */ #define USE_ELF_CORE_DUMP #define ELF_EXEC_PAGESIZE 4096 -#endif +#endif /* TARGET_I386 */ #ifdef TARGET_ARM diff --git a/linux-user/i386/Makefile.vdso b/linux-user/i386/Makefile.vdso new file mode 100644 index 0000000000..95bc616f6d --- /dev/null +++ b/linux-user/i386/Makefile.vdso @@ -0,0 +1,11 @@ +include $(BUILD_DIR)/tests/tcg/i386-linux-user/config-target.mak + +SUBDIR = $(SRC_PATH)/linux-user/i386 +VPATH += $(SUBDIR) + +all: $(SUBDIR)/vdso.so + +$(SUBDIR)/vdso.so: vdso.S vdso.ld vdso-asmoffset.h + $(CC) -o $@ -m32 -nostdlib -shared -Wl,-h,linux-gate.so.1 \ + -Wl,--build-id=sha1 -Wl,--hash-style=both \ + -Wl,-T,$(SUBDIR)/vdso.ld $< diff --git a/linux-user/i386/meson.build b/linux-user/i386/meson.build index ee523019a5..d42fc6cbc9 100644 --- a/linux-user/i386/meson.build +++ b/linux-user/i386/meson.build @@ -3,3 +3,10 @@ syscall_nr_generators += { arguments: [ meson.current_source_dir() / 'syscallhdr.sh', '@INPUT@', '@OUTPUT@', '@EXTRA_ARGS@' ], output: '@BASENAME@_nr.h') } + +vdso_inc = gen_vdso.process('vdso.so', extra_args: [ + '-s', '__kernel_sigreturn', + '-r', '__kernel_rt_sigreturn' + ]) + +linux_user_ss.add(when: 'TARGET_I386', if_true: vdso_inc) diff --git a/linux-user/i386/signal.c b/linux-user/i386/signal.c index 60fa07d6f9..bc5d45302e 100644 --- a/linux-user/i386/signal.c +++ b/linux-user/i386/signal.c @@ -214,6 +214,17 @@ struct rt_sigframe { }; #define TARGET_RT_SIGFRAME_FXSAVE_OFFSET ( \ offsetof(struct rt_sigframe, fpstate) + TARGET_FPSTATE_FXSAVE_OFFSET) + +/* + * Verify that vdso-asmoffset.h constants match. + */ +#include "i386/vdso-asmoffset.h" + +QEMU_BUILD_BUG_ON(offsetof(struct sigframe, sc.eip) + != SIGFRAME_SIGCONTEXT_eip); +QEMU_BUILD_BUG_ON(offsetof(struct rt_sigframe, uc.tuc_mcontext.eip) + != RT_SIGFRAME_SIGCONTEXT_eip); + #else struct rt_sigframe { diff --git a/linux-user/i386/vdso-asmoffset.h b/linux-user/i386/vdso-asmoffset.h new file mode 100644 index 0000000000..4e5ee0dd49 --- /dev/null +++ b/linux-user/i386/vdso-asmoffset.h @@ -0,0 +1,6 @@ +/* + * offsetof(struct sigframe, sc.eip) + * offsetof(struct rt_sigframe, uc.tuc_mcontext.eip) + */ +#define SIGFRAME_SIGCONTEXT_eip 64 +#define RT_SIGFRAME_SIGCONTEXT_eip 220 diff --git a/linux-user/i386/vdso.S b/linux-user/i386/vdso.S new file mode 100644 index 0000000000..e7a1f333a1 --- /dev/null +++ b/linux-user/i386/vdso.S @@ -0,0 +1,143 @@ +/* + * i386 linux replacement vdso. + * + * Copyright 2023 Linaro, Ltd. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include +#include "vdso-asmoffset.h" + +.macro endf name + .globl \name + .type \name, @function + .size \name, . - \name +.endm + +.macro vdso_syscall1 name, nr +\name: + .cfi_startproc + mov %ebx, %edx + .cfi_register %ebx, %edx + mov 4(%esp), %ebx + mov $\nr, %eax + int $0x80 + mov %edx, %ebx + ret + .cfi_endproc +endf \name +.endm + +.macro vdso_syscall2 name, nr +\name: + .cfi_startproc + mov %ebx, %edx + .cfi_register %ebx, %edx + mov 4(%esp), %ebx + mov 8(%esp), %ecx + mov $\nr, %eax + int $0x80 + mov %edx, %ebx + ret + .cfi_endproc +endf \name +.endm + +.macro vdso_syscall3 name, nr +\name: + .cfi_startproc + push %ebx + .cfi_adjust_cfa_offset 4 + .cfi_rel_offset %ebx, 0 + mov 8(%esp), %ebx + mov 12(%esp), %ecx + mov 16(%esp), %edx + mov $\nr, %eax + int $0x80 + pop %ebx + .cfi_adjust_cfa_offset -4 + .cfi_restore %ebx + ret + .cfi_endproc +endf \name +.endm + +__kernel_vsyscall: + .cfi_startproc + int $0x80 + ret + .cfi_endproc +endf __kernel_vsyscall + +vdso_syscall2 __vdso_clock_gettime, __NR_clock_gettime +vdso_syscall2 __vdso_clock_gettime64, __NR_clock_gettime64 +vdso_syscall2 __vdso_clock_getres, __NR_clock_getres +vdso_syscall2 __vdso_gettimeofday, __NR_gettimeofday +vdso_syscall1 __vdso_time, __NR_time +vdso_syscall3 __vdso_getcpu, __NR_gettimeofday + +/* + * Signal return handlers. + */ + + .cfi_startproc simple + .cfi_signal_frame + +/* + * For convenience, put the cfa just above eip in sigcontext, and count + * offsets backward from there. Re-compute the cfa in the two contexts + * we have for signal unwinding. This is far simpler than the + * DW_CFA_expression form that the kernel uses, and is equally correct. + */ + + .cfi_def_cfa %esp, SIGFRAME_SIGCONTEXT_eip + 4 + + .cfi_offset %eip, -4 + /* err, -8 */ + /* trapno, -12 */ + .cfi_offset %eax, -16 + .cfi_offset %ecx, -20 + .cfi_offset %edx, -24 + .cfi_offset %ebx, -28 + .cfi_offset %esp, -32 + .cfi_offset %ebp, -36 + .cfi_offset %esi, -40 + .cfi_offset %edi, -44 + +/* + * While this frame is marked as a signal frame, that only applies to how + * the return address is handled for the outer frame. The return address + * that arrived here, from the inner frame, is not marked as a signal frame + * and so the unwinder still tries to subtract 1 to examine the presumed + * call insn. Thus we must extend the unwind info to a nop before the start. + */ + nop + +__kernel_sigreturn: + popl %eax /* pop sig */ + .cfi_adjust_cfa_offset -4 + movl $__NR_sigreturn, %eax + int $0x80 +endf __kernel_sigreturn + + .cfi_def_cfa_offset RT_SIGFRAME_SIGCONTEXT_eip + 4 + nop + +__kernel_rt_sigreturn: + movl $__NR_rt_sigreturn, %eax + int $0x80 +endf __kernel_rt_sigreturn + + .cfi_endproc + +/* + * TODO: Add elf notes. E.g. + * + * #include + * ELFNOTE_START(Linux, 0, "a") + * .long LINUX_VERSION_CODE + * ELFNOTE_END + * + * but what version number would we set for QEMU? + */ diff --git a/linux-user/i386/vdso.ld b/linux-user/i386/vdso.ld new file mode 100644 index 0000000000..326b7a8f98 --- /dev/null +++ b/linux-user/i386/vdso.ld @@ -0,0 +1,76 @@ +/* + * Linker script for linux i386 replacement vdso. + * + * Copyright 2023 Linaro, Ltd. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +ENTRY(__kernel_vsyscall) + +VERSION { + LINUX_2.6 { + global: + __vdso_clock_gettime; + __vdso_gettimeofday; + __vdso_time; + __vdso_clock_getres; + __vdso_clock_gettime64; + __vdso_getcpu; + }; + + LINUX_2.5 { + global: + __kernel_vsyscall; + __kernel_sigreturn; + __kernel_rt_sigreturn; + local: *; + }; +} + +PHDRS { + phdr PT_PHDR FLAGS(4) PHDRS; + load PT_LOAD FLAGS(7) FILEHDR PHDRS; /* FLAGS=RWX */ + dynamic PT_DYNAMIC FLAGS(4); + eh_frame_hdr PT_GNU_EH_FRAME; + note PT_NOTE FLAGS(4); +} + +SECTIONS { + . = SIZEOF_HEADERS; + + /* + * The following, including the FILEHDRS and PHDRS, are modified + * when we relocate the binary. We want them to be initially + * writable for the relocation; we'll force them read-only after. + */ + .note : { *(.note*) } :load :note + .dynamic : { *(.dynamic) } :load :dynamic + .dynsym : { *(.dynsym) } :load + .data : { + /* + * There ought not be any real read-write data. + * But since we manipulated the segment layout, + * we have to put these sections somewhere. + */ + *(.data*) + *(.sdata*) + *(.got.plt) *(.got) + *(.gnu.linkonce.d.*) + *(.bss*) + *(.dynbss*) + *(.gnu.linkonce.b.*) + } + + .rodata : { *(.rodata*) } + .hash : { *(.hash) } + .gnu.hash : { *(.gnu.hash) } + .dynstr : { *(.dynstr) } + .gnu.version : { *(.gnu.version) } + .gnu.version_d : { *(.gnu.version_d) } + .gnu.version_r : { *(.gnu.version_r) } + .eh_frame_hdr : { *(.eh_frame_hdr) } :load :eh_frame_hdr + .eh_frame : { *(.eh_frame) } :load + + .text : { *(.text*) } :load =0x90909090 +} diff --git a/linux-user/i386/vdso.so b/linux-user/i386/vdso.so new file mode 100755 index 0000000000..bdece5dfcf Binary files /dev/null and b/linux-user/i386/vdso.so differ