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<h5 class="subsubsection">9.42.3.4 Relocations</h5>
<p><a name="index-Sparc-relocations-2026"></a><a name="index-relocations_002c-Sparc-2027"></a>
ELF relocations are available as defined in the 32-bit and 64-bit
Sparc ELF specifications.
<p><code>R_SPARC_HI22</code> is obtained using ‘<samp><span class="samp">%hi</span></samp>’ and <code>R_SPARC_LO10</code>
is obtained using ‘<samp><span class="samp">%lo</span></samp>’. Likewise <code>R_SPARC_HIX22</code> is
obtained from ‘<samp><span class="samp">%hix</span></samp>’ and <code>R_SPARC_LOX10</code> is obtained
using ‘<samp><span class="samp">%lox</span></samp>’. For example:
<pre class="example"> sethi %hi(symbol), %g1
or %g1, %lo(symbol), %g1
sethi %hix(symbol), %g1
xor %g1, %lox(symbol), %g1
</pre>
<p>These “high” mnemonics extract bits 31:10 of their operand,
and the “low” mnemonics extract bits 9:0 of their operand.
<p>V9 code model relocations can be requested as follows:
<ul>
<li><code>R_SPARC_HH22</code> is requested using ‘<samp><span class="samp">%hh</span></samp>’. It can
also be generated using ‘<samp><span class="samp">%uhi</span></samp>’.
<li><code>R_SPARC_HM10</code> is requested using ‘<samp><span class="samp">%hm</span></samp>’. It can
also be generated using ‘<samp><span class="samp">%ulo</span></samp>’.
<li><code>R_SPARC_LM22</code> is requested using ‘<samp><span class="samp">%lm</span></samp>’.
<li><code>R_SPARC_H44</code> is requested using ‘<samp><span class="samp">%h44</span></samp>’.
<li><code>R_SPARC_M44</code> is requested using ‘<samp><span class="samp">%m44</span></samp>’.
<li><code>R_SPARC_L44</code> is requested using ‘<samp><span class="samp">%l44</span></samp>’ or ‘<samp><span class="samp">%l34</span></samp>’.
<li><code>R_SPARC_H34</code> is requested using ‘<samp><span class="samp">%h34</span></samp>’.
</ul>
<p>The ‘<samp><span class="samp">%l34</span></samp>’ generates a <code>R_SPARC_L44</code> relocation because it
calculates the necessary value, and therefore no explicit
<code>R_SPARC_L34</code> relocation needed to be created for this purpose.
<p>The ‘<samp><span class="samp">%h34</span></samp>’ and ‘<samp><span class="samp">%l34</span></samp>’ relocations are used for the abs34 code
model. Here is an example abs34 address generation sequence:
<pre class="example"> sethi %h34(symbol), %g1
sllx %g1, 2, %g1
or %g1, %l34(symbol), %g1
</pre>
<p>The PC relative relocation <code>R_SPARC_PC22</code> can be obtained by
enclosing an operand inside of ‘<samp><span class="samp">%pc22</span></samp>’. Likewise, the
<code>R_SPARC_PC10</code> relocation can be obtained using ‘<samp><span class="samp">%pc10</span></samp>’.
These are mostly used when assembling PIC code. For example, the
standard PIC sequence on Sparc to get the base of the global offset
table, PC relative, into a register, can be performed as:
<pre class="example"> sethi %pc22(_GLOBAL_OFFSET_TABLE_-4), %l7
add %l7, %pc10(_GLOBAL_OFFSET_TABLE_+4), %l7
</pre>
<p>Several relocations exist to allow the link editor to potentially
optimize GOT data references. The <code>R_SPARC_GOTDATA_OP_HIX22</code>
relocation can obtained by enclosing an operand inside of
‘<samp><span class="samp">%gdop_hix22</span></samp>’. The <code>R_SPARC_GOTDATA_OP_LOX10</code>
relocation can obtained by enclosing an operand inside of
‘<samp><span class="samp">%gdop_lox10</span></samp>’. Likewise, <code>R_SPARC_GOTDATA_OP</code> can be
obtained by enclosing an operand inside of ‘<samp><span class="samp">%gdop</span></samp>’.
For example, assuming the GOT base is in register <code>%l7</code>:
<pre class="example"> sethi %gdop_hix22(symbol), %l1
xor %l1, %gdop_lox10(symbol), %l1
ld [%l7 + %l1], %l2, %gdop(symbol)
</pre>
<p>There are many relocations that can be requested for access to
thread local storage variables. All of the Sparc TLS mnemonics
are supported:
<ul>
<li><code>R_SPARC_TLS_GD_HI22</code> is requested using ‘<samp><span class="samp">%tgd_hi22</span></samp>’.
<li><code>R_SPARC_TLS_GD_LO10</code> is requested using ‘<samp><span class="samp">%tgd_lo10</span></samp>’.
<li><code>R_SPARC_TLS_GD_ADD</code> is requested using ‘<samp><span class="samp">%tgd_add</span></samp>’.
<li><code>R_SPARC_TLS_GD_CALL</code> is requested using ‘<samp><span class="samp">%tgd_call</span></samp>’.
<li><code>R_SPARC_TLS_LDM_HI22</code> is requested using ‘<samp><span class="samp">%tldm_hi22</span></samp>’.
<li><code>R_SPARC_TLS_LDM_LO10</code> is requested using ‘<samp><span class="samp">%tldm_lo10</span></samp>’.
<li><code>R_SPARC_TLS_LDM_ADD</code> is requested using ‘<samp><span class="samp">%tldm_add</span></samp>’.
<li><code>R_SPARC_TLS_LDM_CALL</code> is requested using ‘<samp><span class="samp">%tldm_call</span></samp>’.
<li><code>R_SPARC_TLS_LDO_HIX22</code> is requested using ‘<samp><span class="samp">%tldo_hix22</span></samp>’.
<li><code>R_SPARC_TLS_LDO_LOX10</code> is requested using ‘<samp><span class="samp">%tldo_lox10</span></samp>’.
<li><code>R_SPARC_TLS_LDO_ADD</code> is requested using ‘<samp><span class="samp">%tldo_add</span></samp>’.
<li><code>R_SPARC_TLS_IE_HI22</code> is requested using ‘<samp><span class="samp">%tie_hi22</span></samp>’.
<li><code>R_SPARC_TLS_IE_LO10</code> is requested using ‘<samp><span class="samp">%tie_lo10</span></samp>’.
<li><code>R_SPARC_TLS_IE_LD</code> is requested using ‘<samp><span class="samp">%tie_ld</span></samp>’.
<li><code>R_SPARC_TLS_IE_LDX</code> is requested using ‘<samp><span class="samp">%tie_ldx</span></samp>’.
<li><code>R_SPARC_TLS_IE_ADD</code> is requested using ‘<samp><span class="samp">%tie_add</span></samp>’.
<li><code>R_SPARC_TLS_LE_HIX22</code> is requested using ‘<samp><span class="samp">%tle_hix22</span></samp>’.
<li><code>R_SPARC_TLS_LE_LOX10</code> is requested using ‘<samp><span class="samp">%tle_lox10</span></samp>’.
</ul>
<p>Here are some example TLS model sequences.
<p>First, General Dynamic:
<pre class="example"> sethi %tgd_hi22(symbol), %l1
add %l1, %tgd_lo10(symbol), %l1
add %l7, %l1, %o0, %tgd_add(symbol)
call __tls_get_addr, %tgd_call(symbol)
nop
</pre>
<p>Local Dynamic:
<pre class="example"> sethi %tldm_hi22(symbol), %l1
add %l1, %tldm_lo10(symbol), %l1
add %l7, %l1, %o0, %tldm_add(symbol)
call __tls_get_addr, %tldm_call(symbol)
nop
sethi %tldo_hix22(symbol), %l1
xor %l1, %tldo_lox10(symbol), %l1
add %o0, %l1, %l1, %tldo_add(symbol)
</pre>
<p>Initial Exec:
<pre class="example"> sethi %tie_hi22(symbol), %l1
add %l1, %tie_lo10(symbol), %l1
ld [%l7 + %l1], %o0, %tie_ld(symbol)
add %g7, %o0, %o0, %tie_add(symbol)
sethi %tie_hi22(symbol), %l1
add %l1, %tie_lo10(symbol), %l1
ldx [%l7 + %l1], %o0, %tie_ldx(symbol)
add %g7, %o0, %o0, %tie_add(symbol)
</pre>
<p>And finally, Local Exec:
<pre class="example"> sethi %tle_hix22(symbol), %l1
add %l1, %tle_lox10(symbol), %l1
add %g7, %l1, %l1
</pre>
<p>When assembling for 64-bit, and a secondary constant addend is
specified in an address expression that would normally generate
an <code>R_SPARC_LO10</code> relocation, the assembler will emit an
<code>R_SPARC_OLO10</code> instead.
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