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[PATCH v2 16/36] linux-user/arm: Add vdso and use it for rt_sigreturn
|
From: |
Richard Henderson |
|
Subject: |
[PATCH v2 16/36] linux-user/arm: Add vdso and use it for rt_sigreturn |
|
Date: |
Tue, 6 Jul 2021 16:49:12 -0700 |
Building of the vdsos are not actually wired up to anything, since
we require a cross-compiler. Just check in the files for now.
The thumb vdso will only be used for m-profile, as all of our
a-profile cpus support arm mode.
Cc: qemu-arm@nongnu.org
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/arm/signal.c | 83 +++-----------
linux-user/elfload.c | 24 ++++
linux-user/arm/Makefile.vdso | 17 +++
linux-user/arm/meson.build | 18 +++
linux-user/arm/vdso-arm-be.so | Bin 0 -> 5648 bytes
linux-user/arm/vdso-arm-le.so | Bin 0 -> 5648 bytes
linux-user/arm/vdso-thm-be.so | Bin 0 -> 5620 bytes
linux-user/arm/vdso-thm-le.so | Bin 0 -> 5620 bytes
linux-user/arm/vdso.S | 209 ++++++++++++++++++++++++++++++++++
linux-user/arm/vdso.ld | 74 ++++++++++++
10 files changed, 359 insertions(+), 66 deletions(-)
create mode 100644 linux-user/arm/Makefile.vdso
create mode 100755 linux-user/arm/vdso-arm-be.so
create mode 100755 linux-user/arm/vdso-arm-le.so
create mode 100755 linux-user/arm/vdso-thm-be.so
create mode 100755 linux-user/arm/vdso-thm-le.so
create mode 100644 linux-user/arm/vdso.S
create mode 100644 linux-user/arm/vdso.ld
diff --git a/linux-user/arm/signal.c b/linux-user/arm/signal.c
index 565a355fc4..8edc1b1373 100644
--- a/linux-user/arm/signal.c
+++ b/linux-user/arm/signal.c
@@ -102,40 +102,6 @@ struct rt_sigframe
abi_ulong retcode[4];
};
-/*
- * For ARM syscalls, we encode the syscall number into the instruction.
- */
-#define SWI_SYS_SIGRETURN (0xef000000|(TARGET_NR_sigreturn +
ARM_SYSCALL_BASE))
-#define SWI_SYS_RT_SIGRETURN (0xef000000|(TARGET_NR_rt_sigreturn +
ARM_SYSCALL_BASE))
-
-/*
- * For Thumb syscalls, we pass the syscall number via r7. We therefore
- * need two 16-bit instructions.
- */
-#define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (TARGET_NR_sigreturn))
-#define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 |
(TARGET_NR_rt_sigreturn))
-
-static const abi_ulong retcodes[4] = {
- SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN,
- SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN
-};
-
-/*
- * Stub needed to make sure the FD register (r9) contains the right
- * value.
- */
-static const unsigned long sigreturn_fdpic_codes[3] = {
- 0xe59fc004, /* ldr r12, [pc, #4] to read function descriptor */
- 0xe59c9004, /* ldr r9, [r12, #4] to setup GOT */
- 0xe59cf000 /* ldr pc, [r12] to jump into restorer */
-};
-
-static const unsigned long sigreturn_fdpic_thumb_codes[3] = {
- 0xc008f8df, /* ldr r12, [pc, #8] to read function descriptor */
- 0x9004f8dc, /* ldr r9, [r12, #4] to setup GOT */
- 0xf000f8dc /* ldr pc, [r12] to jump into restorer */
-};
-
static inline int valid_user_regs(CPUARMState *regs)
{
return 1;
@@ -188,9 +154,10 @@ setup_return(CPUARMState *env, struct target_sigaction *ka,
abi_ulong handler = 0;
abi_ulong handler_fdpic_GOT = 0;
abi_ulong retcode;
-
- int thumb;
- int is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info);
+ bool thumb;
+ bool is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info);
+ uint32_t cpsr;
+ int idx;
if (is_fdpic) {
/* In FDPIC mode, ka->_sa_handler points to a function
@@ -208,7 +175,7 @@ setup_return(CPUARMState *env, struct target_sigaction *ka,
thumb = handler & 1;
- uint32_t cpsr = cpsr_read(env);
+ cpsr = cpsr_read(env);
cpsr &= ~CPSR_IT;
if (thumb) {
@@ -222,39 +189,23 @@ setup_return(CPUARMState *env, struct target_sigaction
*ka,
cpsr &= ~CPSR_E;
}
+ /* Our vdso default_sigreturn label is a table of entry points. */
+ idx = is_fdpic * 2 + ((ka->sa_flags & TARGET_SA_SIGINFO) != 0);
+ retcode = default_sigreturn + idx * 16;
+
+ /*
+ * Put the sigreturn code on the stack no matter which return
+ * mechanism we use in order to remain ABI compliant.
+ */
+ memcpy(rc, g2h_untagged(retcode & ~1), 16);
+
if (ka->sa_flags & TARGET_SA_RESTORER) {
if (is_fdpic) {
- /* For FDPIC we ensure that the restorer is called with a
- * correct r9 value. For that we need to write code on
- * the stack that sets r9 and jumps back to restorer
- * value.
- */
- if (thumb) {
- __put_user(sigreturn_fdpic_thumb_codes[0], rc);
- __put_user(sigreturn_fdpic_thumb_codes[1], rc + 1);
- __put_user(sigreturn_fdpic_thumb_codes[2], rc + 2);
- __put_user((abi_ulong)ka->sa_restorer, rc + 3);
- } else {
- __put_user(sigreturn_fdpic_codes[0], rc);
- __put_user(sigreturn_fdpic_codes[1], rc + 1);
- __put_user(sigreturn_fdpic_codes[2], rc + 2);
- __put_user((abi_ulong)ka->sa_restorer, rc + 3);
- }
-
- retcode = rc_addr + thumb;
+ /* Place the function descriptor in slot 3. */
+ __put_user((abi_ulong)ka->sa_restorer, rc + 3);
} else {
retcode = ka->sa_restorer;
}
- } else {
- unsigned int idx = thumb;
-
- if (ka->sa_flags & TARGET_SA_SIGINFO) {
- idx += 2;
- }
-
- __put_user(retcodes[idx], rc);
-
- retcode = rc_addr + thumb;
}
env->regs[0] = usig;
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 8088828f5f..40cc79b129 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -517,6 +517,30 @@ static const char *get_elf_platform(void)
#undef END
}
+#ifdef TARGET_WORDS_BIGENDIAN
+# include "vdso-arm-be.c.inc"
+# include "vdso-thm-be.c.inc"
+#else
+# include "vdso-arm-le.c.inc"
+# include "vdso-thm-le.c.inc"
+#endif
+
+static const VdsoImageInfo *vdso_image_info(void)
+{
+ ARMCPU *cpu = ARM_CPU(thread_cpu);
+
+ /*
+ * The only cpus we support that do *not* have arm mode are m-profile.
+ * It's not really possible to run Linux on these, but this config is
+ * useful for testing gcc. In any case, choose the vdso image that
+ * will work for the target cpu.
+ */
+ return (cpu_isar_feature(aa32_a32, cpu)
+ ? &vdso_arm_image_info
+ : &vdso_thm_image_info);
+}
+#define vdso_image_info vdso_image_info
+
#else
/* 64 bit ARM definitions */
#define ELF_START_MMAP 0x80000000
diff --git a/linux-user/arm/Makefile.vdso b/linux-user/arm/Makefile.vdso
new file mode 100644
index 0000000000..89da6f91ae
--- /dev/null
+++ b/linux-user/arm/Makefile.vdso
@@ -0,0 +1,17 @@
+CROSS_CC ?= arm-linux-gnueabihf-gcc
+LDFLAGS := -nostdlib -shared -Wl,-T,vdso.ld \
+ -Wl,-h,linux-vdso.so.1 -Wl,--hash-style=sysv -Wl,--build-id=sha1
+
+all: vdso-arm-le.so vdso-arm-be.so vdso-thm-le.so vdso-thm-be.so
+
+vdso-arm-le.so: vdso.S vdso.ld Makefile.vdso
+ $(CROSS_CC) $(LDFLAGS) -mlittle-endian -marm vdso.S -o $@
+
+vdso-arm-be.so: vdso.S vdso.ld Makefile.vdso
+ $(CROSS_CC) $(LDFLAGS) -mbig-endian -marm vdso.S -o $@
+
+vdso-thm-le.so: vdso.S vdso.ld Makefile.vdso
+ $(CROSS_CC) $(LDFLAGS) -mlittle-endian -mthumb vdso.S -o $@
+
+vdso-thm-be.so: vdso.S vdso.ld Makefile.vdso
+ $(CROSS_CC) $(LDFLAGS) -mbig-endian -mthumb vdso.S -o $@
diff --git a/linux-user/arm/meson.build b/linux-user/arm/meson.build
index 5a93c925cf..66072411d6 100644
--- a/linux-user/arm/meson.build
+++ b/linux-user/arm/meson.build
@@ -5,3 +5,21 @@ syscall_nr_generators += {
arguments: [ meson.current_source_dir() / 'syscallhdr.sh',
'@INPUT@', '@OUTPUT@', '@EXTRA_ARGS@' ],
output: '@BASENAME@_nr.h')
}
+
+# ??? There does not seem to be a way to do
+# when: ['TARGET_ARM', !'TARGET_WORDS_BIGENDIAN']
+# so we'd need to add TARGET_WORDS_LITTLEENDIAN.
+# In the meantime, build both files for arm and armeb.
+
+gen = [
+ gen_vdso.process('vdso-arm-be.so',
+ extra_args: ['-s', 'sigreturn_codes', '-p', 'vdso_arm']),
+ gen_vdso.process('vdso-arm-le.so',
+ extra_args: ['-s', 'sigreturn_codes', '-p', 'vdso_arm']),
+ gen_vdso.process('vdso-thm-be.so',
+ extra_args: ['-s', 'sigreturn_codes', '-p', 'vdso_thm']),
+ gen_vdso.process('vdso-thm-le.so',
+ extra_args: ['-s', 'sigreturn_codes', '-p', 'vdso_thm']),
+]
+
+linux_user_ss.add(when: 'TARGET_ARM', if_true: gen)
diff --git a/linux-user/arm/vdso-arm-be.so b/linux-user/arm/vdso-arm-be.so
new file mode 100755
index
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diff --git a/linux-user/arm/vdso-arm-le.so b/linux-user/arm/vdso-arm-le.so
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diff --git a/linux-user/arm/vdso-thm-be.so b/linux-user/arm/vdso-thm-be.so
new file mode 100755
index
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GIT binary patch
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diff --git a/linux-user/arm/vdso-thm-le.so b/linux-user/arm/vdso-thm-le.so
new file mode 100755
index
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GIT binary patch
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diff --git a/linux-user/arm/vdso.S b/linux-user/arm/vdso.S
new file mode 100644
index 0000000000..1831b29efc
--- /dev/null
+++ b/linux-user/arm/vdso.S
@@ -0,0 +1,209 @@
+/*
+ * arm linux replacement vdso.
+ *
+ * Copyright 2021 Linaro, Ltd.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include <asm/unistd.h>
+
+ .text
+ .eabi_attribute Tag_FP_arch, 0
+
+#ifdef __thumb__
+ .thumb
+ .arch armv7-m
+ .eabi_attribute Tag_ARM_ISA_use, 0
+ .eabi_attribute Tag_CPU_arch, 13 /* TAG_CPU_ARCH_V7_M */
+
+.macro raw_syscall n
+ .ifne \n < 0x100
+ mov r7, #\n
+ .else
+ ldr r7, =\n
+ .endif
+ swi #0
+.endm
+
+.macro fdpic_thunk ofs
+ ldr r3, [sp, #\ofs]
+ ldmia r2, {r2, r3}
+ mov r9, r3
+ bx r2
+.endm
+
+#else
+ .arm
+ .arch armv4t
+ .eabi_attribute Tag_THUMB_ISA_use, 0
+
+.macro raw_syscall n
+ .ifne \n < 0x100
+ mov r7, #\n
+ .else
+ mov r7, #(\n & 0xff)
+ orr r7, r7, #(\n & 0xff00)
+ .endif
+ svc #(\n | __NR_OABI_SYSCALL_BASE)
+.endm
+
+.macro fdpic_thunk ofs
+ ldr r3, [sp, #\ofs]
+ ldmia r3, {r3, r9}
+ bx r3
+.endm
+
+#endif
+
+.macro FUNC name
+ .globl \name
+ .type \name, %function
+#ifdef __thumb__
+ .thumb_func
+#endif
+\name:
+.endm
+
+.macro ENDF name
+ .size \name, . - \name
+.endm
+
+/*
+ * We must save/restore r7 for the EABI syscall number.
+ * While we're doing that, we might as well save LR to get a free return,
+ * and a branch that is interworking back to ARMv5.
+ */
+
+.macro syscall n
+ .cfi_startproc
+ push {r7, lr}
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset r7, -8
+ .cfi_offset lr, -4
+ raw_syscall \n
+ pop {r7, pc}
+ .cfi_endproc
+.endm
+
+FUNC __vdso_clock_gettime
+ syscall __NR_clock_gettime
+ENDF __vdso_clock_gettime
+
+FUNC __vdso_clock_gettime64
+ syscall __NR_clock_gettime64
+ENDF __vdso_clock_gettime64
+
+FUNC __vdso_clock_getres
+ syscall __NR_clock_getres
+ENDF __vdso_clock_getres
+
+FUNC __vdso_gettimeofday
+ syscall __NR_gettimeofday
+ENDF __vdso_gettimeofday
+
+
+/*
+ * We, like the real kernel, use a table of sigreturn trampolines.
+ * Unlike the real kernel, we do not attempt to pack this into as
+ * few bytes as possible -- simply use 16 bytes per slot.
+ *
+ * Within each slot, use the exact same code sequence as the kernel,
+ * lest we trip up someone doing code inspection.
+ */
+
+/* offsetof(struct sigframe, retcode[3]) */
+#define SIGFRAME_RC3_OFFSET 756
+#define RT_SIGFRAME_RC3_OFFSET 884
+
+.macro slot n
+ .balign 16
+ .org sigreturn_codes + 16 * \n
+.endm
+
+/*
+ * Start the unwind info at least one instruction before the signal
+ * trampoline, because the unwinder will assume we are returning
+ * after a call site.
+ */
+ .cfi_startproc simple
+ .cfi_signal_frame
+ .cfi_return_column 15
+
+ .cfi_def_cfa sp, 32 + 64
+ .cfi_offset r0, -16 * 4
+ .cfi_offset r1, -15 * 4
+ .cfi_offset r2, -14 * 4
+ .cfi_offset r3, -13 * 4
+ .cfi_offset r4, -12 * 4
+ .cfi_offset r5, -11 * 4
+ .cfi_offset r6, -10 * 4
+ .cfi_offset r7, -9 * 4
+ .cfi_offset r8, -8 * 4
+ .cfi_offset r9, -7 * 4
+ .cfi_offset r10, -6 * 4
+ .cfi_offset r11, -5 * 4
+ .cfi_offset r12, -4 * 4
+ .cfi_offset r13, -3 * 4
+ .cfi_offset r14, -2 * 4
+ .cfi_offset r15, -1 * 4
+
+ nop
+
+ .balign 16
+FUNC sigreturn_codes
+ /* [EO]ABI sigreturn */
+ slot 0
+ raw_syscall __NR_sigreturn
+
+ .cfi_def_cfa_offset 160 + 64
+
+ /* [EO]ABI rt_sigreturn */
+ slot 1
+ raw_syscall __NR_rt_sigreturn
+
+ .cfi_endproc
+
+ .macro cfi_fdpic_pc ofs
+ /*
+ * fd = *(r13 + ofs)
+ * pc = *fd
+ *
+ * DW_CFA_expression lr (14), length (5),
+ * DW_OP_breg13, ofs, DW_OP_deref, DW_OP_deref
+ */
+ .cfi_escape 0x10, 14, 5, 0x7d, (\ofs & 0x7f) + 0x80, (\ofs >> 7), 0x06,
0x06
+ .endm
+
+ .macro cfi_fdpic_r9 ofs
+ /*
+ * fd = *(r13 + ofs)
+ * r9 = *(fd + 4)
+ *
+ * DW_CFA_expression r9, length (7),
+ * DW_OP_breg13, ofs, DW_OP_deref,
+ * DW_OP_plus_uconst, 4, DW_OP_deref
+ */
+ .cfi_escape 0x10, 9, 7, 0x7d, (\ofs & 0x7f) + 0x80, (\ofs >> 7), 0x06,
0x23, 4, 0x06
+ .endm
+
+ /* FDPIC sigreturn */
+ .cfi_startproc
+ cfi_fdpic_pc SIGFRAME_RC3_OFFSET
+ cfi_fdpic_r9 SIGFRAME_RC3_OFFSET
+
+ slot 2
+ fdpic_thunk SIGFRAME_RC3_OFFSET
+ .cfi_endproc
+
+ /* FDPIC rt_sigreturn */
+ .cfi_startproc
+ cfi_fdpic_pc RT_SIGFRAME_RC3_OFFSET
+ cfi_fdpic_r9 RT_SIGFRAME_RC3_OFFSET
+
+ slot 3
+ fdpic_thunk RT_SIGFRAME_RC3_OFFSET
+ .cfi_endproc
+
+ .balign 16
+ENDF sigreturn_codes
diff --git a/linux-user/arm/vdso.ld b/linux-user/arm/vdso.ld
new file mode 100644
index 0000000000..3bddef97a5
--- /dev/null
+++ b/linux-user/arm/vdso.ld
@@ -0,0 +1,74 @@
+/*
+ * Linker script for linux arm replacement vdso.
+ *
+ * Copyright 2021 Linaro, Ltd.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+VERSION {
+ LINUX_2.6 {
+ global:
+ __vdso_clock_gettime;
+ __vdso_gettimeofday;
+ __vdso_clock_getres;
+ __vdso_clock_gettime64;
+
+ 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);
+ eh_frame_hdr PT_GNU_EH_FRAME;
+ note PT_NOTE FLAGS(4);
+}
+
+SECTIONS {
+ /*
+ * We can't 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.
+ */
+ .note : { *(.note*) } :data :note
+ .dynamic : { *(.dynamic) } :data :dynamic
+ .dynsym : { *(.dynsym) } :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 : {
+ *(.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) } :data :eh_frame_hdr
+ .eh_frame : { *(.eh_frame) } :data
+
+ . = ALIGN(4096);
+ .text : { *(.text*) } :text
+}
--
2.25.1
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