* [PATCH 1/2] linux-user: Build vdso for x64.
2020-05-19 19:44 [PATCH 0/2] linux-user: Load a vdso for x86_64 Richard Henderson
@ 2020-05-19 19:44 ` Richard Henderson
2020-05-19 19:44 ` [PATCH 2/2] linux-user: Load a VDSO for x86-64 Richard Henderson
` (2 subsequent siblings)
3 siblings, 0 replies; 10+ messages in thread
From: Richard Henderson @ 2020-05-19 19:44 UTC (permalink / raw)
To: qemu-devel; +Cc: laurent, Richard Henderson
From: Richard Henderson <rth@twiddle.net>
... Well, sortof. The Makefile bits are broken.
Patch to load the vdso into the running program to follow.
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
Makefile | 4 +-
pc-bios/Makefile | 5 ++
pc-bios/vdso-linux-x64.S | 115 ++++++++++++++++++++++++++++++++++++++
pc-bios/vdso-linux-x64.ld | 81 +++++++++++++++++++++++++++
pc-bios/vdso-linux-x64.so | Bin 0 -> 7500 bytes
5 files changed, 203 insertions(+), 2 deletions(-)
create mode 100644 pc-bios/vdso-linux-x64.S
create mode 100644 pc-bios/vdso-linux-x64.ld
create mode 100755 pc-bios/vdso-linux-x64.so
diff --git a/Makefile b/Makefile
index 40e4f7677b..73e380ac6a 100644
--- a/Makefile
+++ b/Makefile
@@ -848,8 +848,8 @@ qemu_vga.ndrv \
edk2-licenses.txt \
hppa-firmware.img \
opensbi-riscv32-sifive_u-fw_jump.bin opensbi-riscv32-virt-fw_jump.bin \
-opensbi-riscv64-sifive_u-fw_jump.bin opensbi-riscv64-virt-fw_jump.bin
-
+opensbi-riscv64-sifive_u-fw_jump.bin opensbi-riscv64-virt-fw_jump.bin \
+vdso-linux-x64.so
DESCS=50-edk2-i386-secure.json 50-edk2-x86_64-secure.json \
60-edk2-aarch64.json 60-edk2-arm.json 60-edk2-i386.json 60-edk2-x86_64.json
diff --git a/pc-bios/Makefile b/pc-bios/Makefile
index 315288df84..70e2485e2e 100644
--- a/pc-bios/Makefile
+++ b/pc-bios/Makefile
@@ -15,5 +15,10 @@ all: $(TARGETS)
%.dtb: %.dts
dtc -I dts -O dtb -o $@ $<
+vdso-linux-x64.so: vdso-linux-x64.o vdso-linux-x64.ld
+ $(CC) -nostdlib -shared -Wl,-T,vdso-linux-x64.ld \
+ -Wl,-h,linux-vdso.so.1 -Wl,--hash-style=both \
+ vdso-linux-x64.o -o $@
+
clean:
rm -f $(TARGETS) *.o *~
diff --git a/pc-bios/vdso-linux-x64.S b/pc-bios/vdso-linux-x64.S
new file mode 100644
index 0000000000..090d82c26a
--- /dev/null
+++ b/pc-bios/vdso-linux-x64.S
@@ -0,0 +1,115 @@
+/*
+ * x86-64 linux replacement vdso.
+ *
+ * This 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 of the License, or (at your option) any later version.
+ *
+ * This 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 this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <asm/unistd.h>
+
+ .globl __vdso_clock_gettime
+ .type __vdso_clock_gettime, @function
+ .balign 16
+ .cfi_startproc
+__vdso_clock_gettime:
+ mov $__NR_clock_gettime, %eax
+ syscall
+ ret
+ .cfi_endproc
+ .size __vdso_clock_gettime, . - __vdso_clock_gettime
+
+clock_gettime = __vdso_clock_gettime
+ .weak clock_gettime
+
+
+ .globl __vdso_gettimeofday
+ .type __vdso_gettimeofday, @function
+ .balign 16
+ .cfi_startproc
+__vdso_gettimeofday:
+ mov $__NR_gettimeofday, %eax
+ syscall
+ ret
+ .cfi_endproc
+ .size __vdso_gettimeofday, . - __vdso_gettimeofday
+
+gettimeofday = __vdso_gettimeofday
+ .weak gettimeofday
+
+
+ .globl __vdso_time
+ .type __vdso_time, @function
+ .balign 16
+ .cfi_startproc
+__vdso_time:
+ mov $__NR_time, %eax
+ syscall
+ ret
+ .cfi_endproc
+ .size __vdso_time, . - __vdso_time
+
+time = __vdso_time
+ .weak time
+
+
+ .globl __vdso_getcpu
+ .type __vdso_getcpu, @function
+ .balign 16
+ .cfi_startproc
+__vdso_getcpu:
+ /* ??? There is no syscall number for this allocated on x64.
+ We can handle this several ways:
+
+ (1) Invent a syscall number for use within qemu.
+ It should be easy enough to pick a number that
+ is well out of the way of the kernel numbers.
+
+ (2) Force the emulated cpu to support the rdtscp insn,
+ and initialize the TSC_AUX value the appropriate value.
+
+ (3) Pretend that we're always running on cpu 0.
+
+ This last is the one that's implemented here, with the
+ tiny bit of extra code to support rdtscp in place. */
+
+ xor %ecx, %ecx /* rdtscp w/ tsc_aux = 0 */
+
+ /* if (cpu != NULL) *cpu = (ecx & 0xfff); */
+ test %rdi, %rdi
+ jz 1f
+ mov %ecx, %eax
+ and $0xfff, %eax
+ mov %eax, (%rdi)
+
+ /* if (node != NULL) *node = (ecx >> 12); */
+1: test %rsi, %rsi
+ jz 2f
+ shr $12, %ecx
+ mov %ecx, (%rsi)
+
+2: xor %eax, %eax
+ ret
+ .cfi_endproc
+ .size __vdso_getcpu, . - __vdso_getcpu
+
+getcpu = __vdso_getcpu
+ .weak getcpu
+
+/* ??? Perhaps add elf notes. E.g.
+
+ #include <linux/elfnote.h>
+ ELFNOTE_START(Linux, 0, "a")
+ .long LINUX_VERSION_CODE
+ ELFNOTE_END
+
+ but what version number would we set for QEMU? */
diff --git a/pc-bios/vdso-linux-x64.ld b/pc-bios/vdso-linux-x64.ld
new file mode 100644
index 0000000000..2ef21fbcab
--- /dev/null
+++ b/pc-bios/vdso-linux-x64.ld
@@ -0,0 +1,81 @@
+/*
+ * Linker script for linux x64 replacement vdso.
+ *
+ * This 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 of the License, or (at your option) any later version.
+ *
+ * This 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 this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+VERSION {
+ LINUX_2.6 {
+ global:
+ clock_gettime;
+ __vdso_clock_gettime;
+ gettimeofday;
+ __vdso_gettimeofday;
+ getcpu;
+ __vdso_getcpu;
+ time;
+ __vdso_time;
+ local: *;
+ };
+}
+
+PHDRS {
+ phdr PT_PHDR FLAGS(4) PHDRS;
+ data PT_LOAD FLAGS(6) FILEHDR PHDRS;
+ text PT_LOAD FLAGS(5);
+ dynamic PT_DYNAMIC FLAGS(4);
+ note PT_NOTE FLAGS(4);
+ /* ??? Various versions of ld don't know PT_GNU_EH_FRAME. */
+ eh_frame_hdr 0x6474e550;
+}
+
+SECTIONS {
+ /* ??? We can't really prelink to any address without knowing
+ something about the virtual memory space of the host, since
+ that leaks over into the available memory space of the guest. */
+ . = 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. */
+ .dynamic : { *(.dynamic) } :data :dynamic
+ .dynsym : { *(.dynsym) } :data
+ .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.*)
+ }
+
+ . += 4096;
+ .hash : { *(.hash) } :text
+ .gnu.hash : { *(.gnu.hash) }
+ .dynstr : { *(.dynstr) }
+ .gnu.version : { *(.gnu.version) }
+ .gnu.version_d : { *(.gnu.version_d) }
+ .gnu.version_r : { *(.gnu.version_r) }
+ .note : { *(.note*) } :text :note
+ .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
+ .eh_frame : { *(.eh_frame) } :text
+ .rodata : { *(.rodata) }
+
+ . = ALIGN(0x100);
+ .text : { *(.text*) } :text =0x90909090
+}
diff --git a/pc-bios/vdso-linux-x64.so b/pc-bios/vdso-linux-x64.so
new file mode 100755
index 0000000000000000000000000000000000000000..07cba76a4ab52b9bc5be22e2a6e2fe8295691717
GIT binary patch
literal 7500
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literal 0
HcmV?d00001
--
2.20.1
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH 2/2] linux-user: Load a VDSO for x86-64.
2020-05-19 19:44 [PATCH 0/2] linux-user: Load a vdso for x86_64 Richard Henderson
2020-05-19 19:44 ` [PATCH 1/2] linux-user: Build vdso for x64 Richard Henderson
@ 2020-05-19 19:44 ` Richard Henderson
2020-05-28 9:54 ` [PATCH 0/2] linux-user: Load a vdso for x86_64 Laurent Vivier
2020-05-28 10:08 ` Peter Maydell
3 siblings, 0 replies; 10+ messages in thread
From: Richard Henderson @ 2020-05-19 19:44 UTC (permalink / raw)
To: qemu-devel; +Cc: laurent, Richard Henderson
From: Richard Henderson <rth@twiddle.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
linux-user/elfload.c | 203 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 198 insertions(+), 5 deletions(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 01a9323a63..d70e27cb62 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -199,6 +199,8 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs, const CPUX86State *en
(*regs)[26] = env->segs[R_GS].selector & 0xffff;
}
+#define VDSO_BASENAME "vdso-linux-x64.so"
+
#else
#define ELF_START_MMAP 0x80000000
@@ -1499,6 +1501,10 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
#define STACK_ALIGNMENT 16
#endif
+#ifndef VDSO_BASENAME
+#define VDSO_BASENAME NULL
+#endif
+
#ifdef TARGET_ABI32
#undef ELF_CLASS
#define ELF_CLASS ELFCLASS32
@@ -1859,7 +1865,8 @@ static abi_ulong loader_build_fdpic_loadmap(struct image_info *info, abi_ulong s
static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
struct elfhdr *exec,
struct image_info *info,
- struct image_info *interp_info)
+ struct image_info *interp_info,
+ struct image_info *vdso_info)
{
abi_ulong sp;
abi_ulong u_argc, u_argv, u_envp, u_auxv;
@@ -1931,8 +1938,12 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
}
size = (DLINFO_ITEMS + 1) * 2;
- if (k_platform)
+ if (k_platform) {
size += 2;
+ }
+ if (vdso_info) {
+ size += 4;
+ }
#ifdef DLINFO_ARCH_ITEMS
size += DLINFO_ARCH_ITEMS * 2;
#endif
@@ -2009,6 +2020,10 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
if (u_platform) {
NEW_AUX_ENT(AT_PLATFORM, u_platform);
}
+ if (vdso_info) {
+ NEW_AUX_ENT(AT_SYSINFO, vdso_info->entry);
+ NEW_AUX_ENT(AT_SYSINFO_EHDR, vdso_info->load_addr);
+ }
NEW_AUX_ENT (AT_NULL, 0);
#undef NEW_AUX_ENT
@@ -2614,6 +2629,177 @@ static void load_elf_interp(const char *filename, struct image_info *info,
exit(-1);
}
+static void load_elf_vdso(const char *basename, struct image_info *info,
+ char bprm_buf[BPRM_BUF_SIZE])
+{
+ const char *errmsg;
+ char *filename;
+ int fd, retval, i;
+ abi_ulong load_bias;
+
+ /*
+ * ??? What we really need access to is qemu_find_file, but that is
+ * only built for system targets at the moment.
+ */
+ filename = g_build_filename(CONFIG_QEMU_DATADIR, basename, NULL);
+ fd = open(filename, O_RDONLY);
+ if (fd < 0) {
+ goto exit_perror;
+ }
+ g_free(filename);
+
+ retval = read(fd, bprm_buf, BPRM_BUF_SIZE);
+ if (retval < 0) {
+ goto exit_perror;
+ }
+ if (retval < BPRM_BUF_SIZE) {
+ memset(bprm_buf + retval, 0, BPRM_BUF_SIZE - retval);
+ }
+
+ load_elf_image(basename, fd, info, NULL, bprm_buf);
+ load_bias = info->load_bias;
+
+ /*
+ * We most likely need to relocate the VDSO image. The one built into
+ * the kernel is built for a fixed address. The one built for QEMU is
+ * not, since that requires close control of the guest address space.
+ */
+ if (load_bias) {
+ struct elfhdr *ehdr = (struct elfhdr *)bprm_buf;
+ struct elf_phdr *phdr;
+ abi_ulong dynamic_addr = -1;
+ abi_ulong dynsym_addr = -1;
+
+ /*
+ * ??? Assume QEMU's VDSO is built "properly", which arranges
+ * for the PHDRs, and all the sections manipulated below, to
+ * be included with a writable load segment.
+ *
+ * ??? One might think that we'd need to relocate ehdr.e_entry,
+ * but for some reason glibc does that one itself, though that
+ * is also available via the AT_SYSINFO entry.
+ */
+
+ /* Relocate the program headers. */
+ phdr = (struct elf_phdr *)g2h(info->load_addr + ehdr->e_phoff);
+ bswap_phdr(phdr, ehdr->e_phnum);
+ for (i = 0; i < ehdr->e_phnum; ++i) {
+ phdr[i].p_vaddr += load_bias;
+ phdr[i].p_paddr += load_bias;
+ if (phdr[i].p_type == PT_DYNAMIC) {
+ dynamic_addr = phdr[i].p_vaddr;
+ }
+ }
+ bswap_phdr(phdr, ehdr->e_phnum);
+
+ /* Relocate the DYNAMIC entries. */
+ if (dynamic_addr != -1) {
+ abi_ulong tag, val, *dyn = (abi_ulong *)g2h(dynamic_addr);
+ do {
+ tag = tswapl(dyn[0]);
+ val = tswapl(dyn[1]);
+ switch (tag) {
+ case DT_SYMTAB:
+ dynsym_addr = load_bias + val;
+ dyn[1] = tswapl(dynsym_addr);
+ break;
+ case DT_SYMENT:
+ if (val != sizeof(struct elf_sym)) {
+ errmsg = "VDSO has an unexpected dynamic symbol size";
+ goto exit_errmsg;
+ }
+ break;
+
+ case DT_HASH:
+ case DT_STRTAB:
+ case DT_VERDEF:
+ case DT_VERSYM:
+ case DT_ADDRRNGLO ... DT_ADDRRNGHI:
+ /* These entries store an address in the entry. */
+ dyn[1] = tswapl(load_bias + val);
+ break;
+
+ case DT_NULL:
+ case DT_STRSZ:
+ case DT_SONAME:
+ case DT_DEBUG:
+ case DT_FLAGS:
+ case DT_FLAGS_1:
+ case DT_VERDEFNUM:
+ case DT_VALRNGLO ... DT_VALRNGHI:
+ /* These entries store an integer in the entry. */
+ break;
+
+ case DT_REL:
+ case DT_RELA:
+ /*
+ * These entries indicate that the VDSO was built
+ * incorrectly. It should not have real relocations.
+ */
+ errmsg = "VDSO has relocations";
+ goto exit_errmsg;
+ case DT_NEEDED:
+ case DT_VERNEED:
+ errmsg = "VDSO has external dependancies";
+ goto exit_errmsg;
+
+ default:
+ /* This is probably something target specific. */
+ errmsg = "VDSO has unknown DYNAMIC entry";
+ goto exit_errmsg;
+ }
+ dyn += 2;
+ } while (tag != DT_NULL);
+ }
+
+ /* Relocate the dynamic symbol table. */
+ if (dynsym_addr != -1) {
+ struct elf_shdr *shdr;
+ struct elf_sym *sym;
+ int dynsym_size = 0;
+
+ /*
+ * Read the section headers to find out the size of the
+ * dynamic symbol table.
+ */
+ shdr = (struct elf_shdr *)g2h(info->load_addr + ehdr->e_shoff);
+ for (i = 0; i < ehdr->e_shnum; ++i) {
+ abi_ulong addr = tswapl(shdr[i].sh_addr) + load_bias;
+ if (addr == dynsym_addr) {
+ dynsym_size = tswapl(shdr[i].sh_size);
+ break;
+ }
+ }
+
+ sym = (struct elf_sym *)g2h(dynsym_addr);
+ for (i = 0; i < dynsym_size / sizeof(*sym); ++i) {
+ sym[i].st_value = tswapl(tswapl(sym[i].st_value) + load_bias);
+ }
+ }
+ }
+
+ /*
+ * Mark the VDSO writable segment read-only.
+ *
+ * ??? This assumes that the VDSO implementation doesn't actually
+ * have any truely writable data. Perhaps we should instead use
+ * the PT_GNU_RELRO header to indicate that we really want this.
+ */
+ retval = target_mprotect(info->start_data, info->brk - info->start_data,
+ PROT_READ);
+ if (retval < 0) {
+ goto exit_perror;
+ }
+ return;
+
+ exit_perror:
+ errmsg = strerror(errno);
+ exit_errmsg:
+ fprintf(stderr, "%s: %s\n", filename, errmsg);
+ exit(-1);
+}
+
+
static int symfind(const void *s0, const void *s1)
{
target_ulong addr = *(target_ulong *)s0;
@@ -2803,7 +2989,7 @@ uint32_t get_elf_eflags(int fd)
int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
{
- struct image_info interp_info;
+ struct image_info interp_info, vdso_info;
struct elfhdr elf_ex;
char *elf_interpreter = NULL;
char *scratch;
@@ -2879,8 +3065,15 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
#endif
}
- bprm->p = create_elf_tables(bprm->p, bprm->argc, bprm->envc, &elf_ex,
- info, (elf_interpreter ? &interp_info : NULL));
+ /* If we've been given a VDSO to load, do so. */
+ if (VDSO_BASENAME) {
+ load_elf_vdso(VDSO_BASENAME, &vdso_info, bprm->buf);
+ }
+
+ bprm->p = create_elf_tables(bprm->p, bprm->argc, bprm->envc,
+ &elf_ex, info,
+ (elf_interpreter ? &interp_info : NULL),
+ (VDSO_BASENAME ? &vdso_info : NULL));
info->start_stack = bprm->p;
/* If we have an interpreter, set that as the program's entry point.
--
2.20.1
^ permalink raw reply related [flat|nested] 10+ messages in thread