forked from pool/glibc
Andreas Schwab
5767ee0b6c
- ppc64-copysign.patch: Fix ppc64le copysign overwriting parent stack frame (BZ #16786) - aarch64-setcontext.patch: Fix aarch64 setcontext clobbering alternate signal stack (BZ #16629) OBS-URL: https://build.opensuse.org/request/show/228414 OBS-URL: https://build.opensuse.org/package/show/Base:System/glibc?expand=0&rev=351
226 lines
6.5 KiB
Diff
226 lines
6.5 KiB
Diff
From 4dc40de1ed58a1de5d960e59f20a04191f6820c9 Mon Sep 17 00:00:00 2001
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From: Will Newton <will.newton@linaro.org>
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Date: Wed, 12 Mar 2014 16:14:51 +0000
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Subject: [PATCH 1/3] aarch64: Re-implement setcontext without rt_sigreturn
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syscall
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The current implementation of setcontext uses rt_sigreturn to restore
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the contents of registers. This contrasts with the way most other
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architectures implement setcontext:
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powerpc64, mips, tile:
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Call rt_sigreturn if context was created by a call to a signal handler,
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otherwise restore in user code.
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powerpc32:
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Call swapcontext system call and don't call sigreturn or rt_sigreturn.
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x86_64, sparc, hppa, sh, ia64, m68k, s390, arm:
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Only support restoring "synchronous" contexts, that is contexts
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created by getcontext, and restoring in user code and don't call
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sigreturn or rt_sigreturn.
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alpha:
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Call sigreturn (but not rt_sigreturn) in all cases to do the restore.
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The text of the setcontext manpage suggests that the requirement to be
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able to restore a signal handler created context has been dropped from
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SUSv2:
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If the context was obtained by a call to a signal handler, then old
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standard text says that "program execution continues with the program
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instruction following the instruction interrupted by the signal".
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However, this sentence was removed in SUSv2, and the present verdict
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is "the result is unspecified".
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Implementing setcontext by calling rt_sigreturn unconditionally causes
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problems when used with sigaltstack as in BZ #16629. On this basis it
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seems that aarch64 is broken and that new ports should only support
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restoring contexts created with getcontext and do not need to call
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rt_sigreturn at all.
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This patch re-implements the aarch64 setcontext function to restore
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the context in user code in a similar manner to x86_64 and other ports.
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ChangeLog:
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2014-03-13 Will Newton <will.newton@linaro.org>
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[BZ #16629]
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* sysdeps/unix/sysv/linux/aarch64/setcontext.S (__setcontext):
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Re-implement to restore registers in user code and avoid
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rt_sigreturn system call.
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---
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sysdeps/unix/sysv/linux/aarch64/setcontext.S | 147 +++++++++++++++++----------
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1 file changed, 92 insertions(+), 55 deletions(-)
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Index: glibc-2.19/ports/sysdeps/unix/sysv/linux/aarch64/setcontext.S
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===================================================================
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--- glibc-2.19.orig/ports/sysdeps/unix/sysv/linux/aarch64/setcontext.S
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+++ glibc-2.19/ports/sysdeps/unix/sysv/linux/aarch64/setcontext.S
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@@ -22,68 +22,105 @@
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#include "ucontext_i.h"
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#include "ucontext-internal.h"
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-/* int setcontext (const ucontext_t *ucp) */
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+/* int __setcontext (const ucontext_t *ucp)
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- .text
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-
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-ENTRY(__setcontext)
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+ Restores the machine context in UCP and thereby resumes execution
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+ in that context.
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- /* Create a signal frame on the stack:
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+ This implementation is intended to be used for *synchronous* context
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+ switches only. Therefore, it does not have to restore anything
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+ other than the PRESERVED state. */
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- fp
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- lr
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- ...
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- sp-> rt_sigframe
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- */
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-
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- stp x29, x30, [sp, -16]!
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- cfi_adjust_cfa_offset (16)
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- cfi_rel_offset (x29, 0)
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- cfi_rel_offset (x30, 8)
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-
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- mov x29, sp
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- cfi_def_cfa_register (x29)
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-
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- /* Allocate space for the sigcontext. */
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- mov w3, #((RT_SIGFRAME_SIZE + SP_ALIGN_SIZE) & SP_ALIGN_MASK)
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- sub sp, sp, x3
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-
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- /* Compute the base address of the ucontext structure. */
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- add x1, sp, #RT_SIGFRAME_UCONTEXT
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-
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- /* Only ucontext is required in the frame, *copy* it in. */
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-
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-#if UCONTEXT_SIZE % 16
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-#error The implementation of setcontext.S assumes sizeof(ucontext_t) % 16 == 0
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-#endif
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-
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- mov x2, #UCONTEXT_SIZE / 16
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-0:
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- ldp x3, x4, [x0], #16
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- stp x3, x4, [x1], #16
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- sub x2, x2, 1
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- cbnz x2, 0b
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+ .text
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- /* rt_sigreturn () -- no arguments, sp points to struct rt_sigframe. */
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- mov x8, SYS_ify (rt_sigreturn)
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+ENTRY (__setcontext)
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+ /* Save a copy of UCP. */
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+ mov x9, x0
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+
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+ /* Set the signal mask with
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+ rt_sigprocmask (SIG_SETMASK, mask, NULL, _NSIG/8). */
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+ mov x0, #SIG_SETMASK
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+ add x1, x9, #UCONTEXT_SIGMASK
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+ mov x2, #0
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+ mov x3, #_NSIG8
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+ mov x8, SYS_ify (rt_sigprocmask)
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svc 0
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-
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- /* Ooops we failed. Recover the stack */
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-
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- mov sp, x29
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- cfi_def_cfa_register (sp)
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-
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- ldp x29, x30, [sp], 16
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- cfi_adjust_cfa_offset (16)
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- cfi_restore (x29)
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- cfi_restore (x30)
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- b C_SYMBOL_NAME(__syscall_error)
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-
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+ cbz x0, 1f
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+ b C_SYMBOL_NAME (__syscall_error)
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+1:
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+ /* Restore the general purpose registers. */
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+ mov x0, x9
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+ cfi_def_cfa (x0, 0)
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+ cfi_offset (x18, oX0 + 18 * SZREG)
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+ cfi_offset (x19, oX0 + 19 * SZREG)
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+ cfi_offset (x20, oX0 + 20 * SZREG)
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+ cfi_offset (x21, oX0 + 21 * SZREG)
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+ cfi_offset (x22, oX0 + 22 * SZREG)
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+ cfi_offset (x23, oX0 + 23 * SZREG)
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+ cfi_offset (x24, oX0 + 24 * SZREG)
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+ cfi_offset (x25, oX0 + 25 * SZREG)
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+ cfi_offset (x26, oX0 + 26 * SZREG)
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+ cfi_offset (x27, oX0 + 27 * SZREG)
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+ cfi_offset (x28, oX0 + 28 * SZREG)
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+ cfi_offset (x29, oX0 + 29 * SZREG)
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+ cfi_offset (x30, oX0 + 30 * SZREG)
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+
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+ cfi_offset ( d8, oV0 + 8 * SZVREG)
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+ cfi_offset ( d9, oV0 + 9 * SZVREG)
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+ cfi_offset (d10, oV0 + 10 * SZVREG)
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+ cfi_offset (d11, oV0 + 11 * SZVREG)
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+ cfi_offset (d12, oV0 + 12 * SZVREG)
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+ cfi_offset (d13, oV0 + 13 * SZVREG)
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+ cfi_offset (d14, oV0 + 14 * SZVREG)
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+ cfi_offset (d15, oV0 + 15 * SZVREG)
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+ ldp x18, x19, [x0, oX0 + 18 * SZREG]
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+ ldp x20, x21, [x0, oX0 + 20 * SZREG]
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+ ldp x22, x23, [x0, oX0 + 22 * SZREG]
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+ ldp x24, x25, [x0, oX0 + 24 * SZREG]
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+ ldp x26, x27, [x0, oX0 + 26 * SZREG]
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+ ldp x28, x29, [x0, oX0 + 28 * SZREG]
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+ ldr x30, [x0, oX0 + 30 * SZREG]
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+ ldr x2, [x0, oSP]
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+ mov sp, x2
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+
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+ /* Check for FP SIMD context. */
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+ add x2, x0, #oEXTENSION
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+
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+ mov w3, #(FPSIMD_MAGIC & 0xffff)
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+ movk w3, #(FPSIMD_MAGIC >> 16), lsl #16
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+ ldr w1, [x2, #oHEAD + oMAGIC]
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+ cmp w1, w3
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+ b.ne 2f
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+
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+ /* Restore the FP SIMD context. */
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+ add x3, x2, #oV0 + 8 * SZVREG
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+ ldp d8, d9, [x3], #2 * SZVREG
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+ ldp d10, d11, [x3], #2 * SZVREG
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+ ldp d12, d13, [x3], #2 * SZVREG
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+ ldp d14, d15, [x3], #2 * SZVREG
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+
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+ add x3, x2, oFPSR
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+
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+ ldr w4, [x3]
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+ msr fpsr, x4
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+
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+ ldr w4, [x3, oFPCR - oFPSR]
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+ msr fpcr, x4
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+
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+2:
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+ ldr x16, [x0, oPC]
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+ /* Restore arg registers. */
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+ ldp x2, x3, [x0, oX0 + 2 * SZREG]
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+ ldp x4, x5, [x0, oX0 + 4 * SZREG]
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+ ldp x6, x7, [x0, oX0 + 6 * SZREG]
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+ ldp x0, x1, [x0, oX0 + 0 * SZREG]
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+ /* Jump to the new pc value. */
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+ br x16
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PSEUDO_END (__setcontext)
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weak_alias (__setcontext, setcontext)
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-ENTRY(__startcontext)
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+ENTRY (__startcontext)
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mov x0, x19
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cbnz x0, __setcontext
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-1: b HIDDEN_JUMPTARGET(_exit)
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-END(__startcontext)
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+1: b HIDDEN_JUMPTARGET (_exit)
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+END (__startcontext)
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