Changeset 05cb995 in mainline

Timestamp:

2019-01-11T08:37:49Z (6 years ago)

Author:

Vojtech Horky <vojtech.horky@…>

Children:

3e40b4e

Parents:

d3e938c

git-author:

Vojtech Horky <vojtech.horky@…> (2019-01-09 13:10:03)

git-committer:

Vojtech Horky <vojtech.horky@…> (2019-01-11 08:37:49)

Message:

mips32: clobber memory on sycall (thx Adam Frey)

As the syscall may touch arbitrary memory, we need to prevent the
compiler to cache some values in registers.

Actual problem was demonstrated on Kalisto during school assignments but
HelenOS uses basically the same code, thus the issue applies here too.

File:

• uspace/lib/c/arch/mips32/src/syscall.c (modified) (1 diff)

uspace/lib/c/arch/mips32/src/syscall.c

@@ -57 +57 @@
               "r" (__mips_reg_t1),
               "r" (__mips_reg_v0)
+            :
               /*
                * We are a function call, although C
                * does not know it.
                */
-            : "%ra"
+              "%ra",
+              /*
+               * Clobber memory too as some arguments might be
+               * actually pointers.
+               */
+              "memory"
         );