Commit 18e0e95f authored by Sergei Trofimovich's avatar Sergei Trofimovich Committed by Austin Seipp

powerpc: add basic support for PLT relocations (#10402)

Commit a93ab43a
enabled support for proper PIC relocations from
assembler.

Commit adds support for relocations of type:
    R_PPC_REL16_HI
    R_PPC_REL16_HA
    R_PPC_REL16_LO
    R_PPC_PLTREL24

They are used only when GHC is built in
    DYNAMIC_GHC_PROGRAMS = NO
mode.

Verified by running the following test:

    // cat a.c
    #include <stdio.h>

    void ffi_a_hello (int i) {
        fprintf (stderr, "WEEEEEEEE: i=%d\n", i);
    }

    -- cat A.hs
    {-# LANGUAGE ForeignFunctionInterface #-}
    module A where

    import Foreign.C

    foreign import ccall "ffi_a_hello" a :: CInt -> IO ()

    # ghc -fPIC -c a.c -fforce-recomp
    # ghc -fPIC -c A.hs -fforce-recomp
    # ghc --interactive ./a.o A
    ...
    *A> a 42
    WEEEEEEEE: i=42
See gory details in Trac #10402.
Signed-off-by: default avatarColin Watson <cjwatson@debian.org>
Signed-off-by: default avatarSergei Trofimovich <siarheit@google.com>

Reviewed By: bgamari, austin

Differential Revision: https://phabricator.haskell.org/D996

GHC Trac Issues: #10402

(cherry picked from commit c0847967)
parent dd928e1c
......@@ -5956,6 +5956,9 @@ do_Elf_Rela_relocations ( ObjectCode* oc, char* ehdrC,
*(Elf32_Word *) P = value - P;
break;
case R_PPC_PLTREL24:
value -= 0x8000; /* See Note [.LCTOC1 in PPC PIC code] */
/* fallthrough */
case R_PPC_REL24:
delta = value - P;
......@@ -5976,6 +5979,18 @@ do_Elf_Rela_relocations ( ObjectCode* oc, char* ehdrC,
*(Elf_Word *) P = (*(Elf_Word *) P & 0xfc000003)
| (delta & 0x3fffffc);
break;
case R_PPC_REL16_LO:
*(Elf32_Half*) P = value - P;
break;
case R_PPC_REL16_HI:
*(Elf32_Half*) P = (value - P) >> 16;
break;
case R_PPC_REL16_HA:
*(Elf32_Half*) P = (value + 0x8000 - P) >> 16;
break;
# endif
#if x86_64_HOST_ARCH
......
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