[Bug 1881450] [NEW] Emulation of a math function fails for m68k Linux user mode

[Ahmed Karaman]

Public bug reported:

Please check the attached math-example.c file.
When running the m68k executable under QEMU, it results in an 
"Illegal instruction" error.
Other targets don't produce this error.

Steps to reproduce the bug:

1. Download the math-example.c attached file.
2. Compile it by running:
   m68k-linux-gnu-gcc -O2 -static math-example.c -o math-example-m68k -lm
3. Run the executable with QEMU:
   /build/qemu-5.0.0/build-gcc/m68k-linux-user/qemu-m68k math-example-m68k

The output of execution is:
   Profiling function expm1f():
   qemu: uncaught target signal 4 (Illegal instruction) - core dumped
   Illegal instruction (core dumped)

Output when running on other targets:
   Profiling function expm1f():
     Elapsed time: 47 ms
     Control result: 71804.953125

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: m68k

** Attachment added: "Emulating the expm1f() function."
   
https://bugs.launchpad.net/bugs/1881450/+attachment/5378913/+files/math-example.c

** Description changed:

  Please check the attached math-example.c file.
- When running the m68k executable under QEMU, it results in an "Illegal 
instruction" error.
+ When running the m68k executable under QEMU, it results in an 
+ "Illegal instruction" error.
  Other targets don't produce this error.
  
  Steps to reproduce the bug:
  
  1. Download the math-example.c attached file.
  2. Compile it by running:
-         m68k-linux-gnu-gcc -O2 -static math-example.c -o math-example-m68k -lm
+    m68k-linux-gnu-gcc -O2 -static math-example.c -o math-example-m68k -lm
  3. Run the executable with QEMU:
-         /build/qemu-5.0.0/build-gcc/m68k-linux-user/qemu-m68k 
math-example-m68k 
+    /build/qemu-5.0.0/build-gcc/m68k-linux-user/qemu-m68k math-example-m68k
  
  The output of execution is:
-         Profiling function expm1f():
-         qemu: uncaught target signal 4 (Illegal instruction) - core dumped
-         Illegal instruction (core dumped)
+    Profiling function expm1f():
+    qemu: uncaught target signal 4 (Illegal instruction) - core dumped
+    Illegal instruction (core dumped)
  
- Expected output:
-         Profiling function expm1f():
-           Elapsed time: 47 ms
-           Control result: 71804.953125
+ Output when running on other targets:
+    Profiling function expm1f():
+      Elapsed time: 47 ms
+      Control result: 71804.953125

** Attachment removed: "math-example.c"
   
https://bugs.launchpad.net/qemu/+bug/1881450/+attachment/5378913/+files/math-example.c

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https://bugs.launchpad.net/bugs/1881450

Title:
  Emulation of a math function fails for m68k Linux user mode

Status in QEMU:
  New

Bug description:
  Please check the attached math-example.c file.
  When running the m68k executable under QEMU, it results in an 
  "Illegal instruction" error.
  Other targets don't produce this error.

  Steps to reproduce the bug:

  1. Download the math-example.c attached file.
  2. Compile it by running:
     m68k-linux-gnu-gcc -O2 -static math-example.c -o math-example-m68k -lm
  3. Run the executable with QEMU:
     /build/qemu-5.0.0/build-gcc/m68k-linux-user/qemu-m68k math-example-m68k

  The output of execution is:
     Profiling function expm1f():
     qemu: uncaught target signal 4 (Illegal instruction) - core dumped
     Illegal instruction (core dumped)

  Output when running on other targets:
     Profiling function expm1f():
       Elapsed time: 47 ms
       Control result: 71804.953125

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