diff options
| author | Alan Modra <amodra@gmail.com> | 2013-08-17 18:36:45 +0930 |
|---|---|---|
| committer | Alan Modra <amodra@gmail.com> | 2013-10-04 10:38:59 +0930 |
| commit | 0b2c2ace3601d5d59cf89130b16840e7f132f7a6 (patch) | |
| tree | 0a96e682a1ff8f61773d41e00ba55485ee7d4c86 /sysdeps/unix/sysv/linux | |
| parent | 02f04a6c7fea2b474b026bbce721d8c658d71fda (diff) | |
PowerPC makecontext
http://sourceware.org/ml/libc-alpha/2013-08/msg00092.html
Use conditional form of branch and link to avoid destroying the cpu
link stack used to predict blr return addresses.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S: Use
conditional form of branch and link when obtaining pc.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S: Likewise.
Diffstat (limited to 'sysdeps/unix/sysv/linux')
| -rw-r--r-- | sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S | 8 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S | 6 |
2 files changed, 10 insertions, 4 deletions
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S index 95902b13f9..70e3c97626 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S @@ -47,7 +47,9 @@ ENTRY(__makecontext) #ifdef PIC mflr r0 cfi_register(lr,r0) - bl 1f + /* Use this conditional form of branch and link to avoid destroying + the cpu link stack used to predict blr return addresses. */ + bcl 20,31,1f 1: mflr r6 addi r6,r6,L(exitcode)-1b mtlr r0 @@ -136,7 +138,9 @@ ENTRY(__novec_makecontext) #ifdef PIC mflr r0 cfi_register(lr,r0) - bl 1f + /* Use this conditional form of branch and link to avoid destroying + the cpu link stack used to predict blr return addresses. */ + bcl 20,31,1f 1: mflr r6 addi r6,r6,L(novec_exitcode)-1b mtlr r0 diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S index 4a16669383..32fc47c3f3 100644 --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S @@ -124,8 +124,10 @@ L(noparms): /* If the target function returns we need to do some cleanup. We use a code trick to get the address of our cleanup function into the link - register. Do not add any code between here and L(exitcode). */ - bl L(gotexitcodeaddr); + register. Do not add any code between here and L(exitcode). + Use this conditional form of branch and link to avoid destroying + the cpu link stack used to predict blr return addresses. */ + bcl 20,31,L(gotexitcodeaddr); /* This is the helper code which gets called if a function which is registered with 'makecontext' returns. In this case we |