<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/64999>64999</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LTO][PIC][ARM][SSP] extra indirection accessing __stack_chk_guard
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          wolfy1961
      </td>
    </tr>
</table>

<pre>
    After commit [e018cbf7208b](https://github.com/llvm/llvm-project/commit/e018cbf7208b3d34f18997ddee84c66cee32fb1b) we're seeing segfaults when accessing __stack_chk_guard when using LTO. I'm attaching a small test case (3 source files and small build script) that shows the problem). When compiling with -flto -fPIC and linking without any additional flags, we're seeing the following code in the function foo:
``` 
201dc: e59f006c      ldr     r0, [pc, #0x6c]         @ 0x20250 <foo+0x80>
201e0: e5900000      ldr     r0, [r0]
201e4: e5900000 ldr     r0, [r0]
201e8: e50b000c      str     r0, [r11, #-0xc]
...
20250: 54 02 03 00   .word   0x00030254
```
And from the linker map file:
```
30254    30254        4     1 __stack_chk_guard
```
So we're seeing an extra indirection, causing the segfaults.

If we're adding -pie to the link line, things work fine. We see:
```
   10280: e59f0074      ldr     r0, [pc, #0x74]         @ 0x102fc <foo+0x88>
   10284: e08f0000      add     r0, pc, r0
   10288: e5900000      ldr     r0, [r0]
   1028c: e5900000      ldr     r0, [r0]
    ...
   102fc: e4 00 01 00   .word   0x000100e4
```
with the GOT present in the executable.

Note that the the test case is not meant to execute anywhere. A rudimentary module (rt.c) supplies the missing definitions.
[stack_check.zip](https://github.com/llvm/llvm-project/files/12444315/stack_check.zip)

</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJycVd2O4ygTfRpyU2qrjH9iX-Qi6f7yqaXZndHOSHPZwriI2cbGArxJ79OvsJP09M_sqBclNhjqnKriUAjv9WEg2rBix4q7lZhCZ93maI16SusyXTW2fdpsVSAH0va9DsCKHWFayUatOVYNK-4Yr7oQRs-yLeN7xvcHHbqpSaTtGd8b89fldTM6-yfJwPh-AWN8_yNW1ma5Squ6XrctUZXLspREGVdN2jBew5EYXzsCT6SHA3g6KDGZ4OHY0QBCSvI-Tjw8-CDk44PsHh8Ok3DtsmCaJz99-5zAPePrHkQIQnbxowDfC2MgkA8ghSdgvMrA28lJAqUNeRBDe17VTNq04KXTY4h-hU4E8J09eggdwehsY6hnvE7geySWth-1iTxHHTq4USZYuFFf7m9nUKOHx8uknQKI4QlE2-qg7SAMKCMOnvHb1-FHKmWNscc4krYl0MPydRpkNAZlbdwUvGO4ZSUuP1jGHNNWsmwLVNQKsZQwN9O6-e0wUrJiN8q5wzM8lZIVd3BpLEfAE0deILDsNnLxHZ4qZNn_rhSEZwqM7ScUDqOKrib5C5Nfra6W1dgg4jkGH16bpOk5iBs8yat5kiQXHF7MjhY5IAfMYPY1OVrXAgCeEDFDXuSvUrkMt0MLytl-zn3cTHLQi3GWzdv0L8MZLfp47cS2dNK3An4X46t9LQkxAJ2CE6CHVjuaRRADl2LRfnTwemrOsS_Pe3XFitIbDnAzaoJgr0HFB0WwEE-Mh6N1j6D0QAl8nx34WagxIuQVPmttnf9aa-v8rdZS5Eq-0Fp11dqZZdEOVupZbqJtf2BZKNxL36qPifRsJT9sBVfFLRBqgcij3DB9R3QpIr0vurmSxL35_-dvMDryNITL-acTySmIxtCLPf7dBlpqVVw0_6_lTnsYbICexBDiri8QFGvRsSNHCWzBTa3uaQjCPUFv28nMVdKFRMYi6KdxNJqWEtjrpRK3pPQwF7Kr3IrdRdskH5O_9fgfb5C5KDO-T3me51laML5_DczrhXPVbrK2zmqxok1a1hmmvODpqtuUTdmUdZHiuhFrgetK1nUmhZJNk6u6Xq_0hiPPsOIlpmnB06Rax1LDsZW1ykVZsBypF9ok0bvEusNKez_Rpszrul4Z0ZDxl8vVbeYQmungWY5G--CfzYIOZr6GP337HDNS7L7c3y6d7R-_LZ2vX7_EQ_HmiP_b1beanNl8OLlzEDG7cxz_BAAA__97Llpy">