MIPS: Ignore relocs against __ex_table for relocatable kernel

Since commit 6f2c2f93a190 ("scripts/sorttable: Remove unneeded
Elf_Rel"), sorttable no longer clears relocs against __ex_table,
claiming "it was never used."  But in fact MIPS relocatable kernel had
been implicitly depending on this behavior, so after this commit the
MIPS relocatable kernel has started to spit oops like:

	CPU 1 Unable to handle kernel paging request at virtual address 000000fffbbdbff8, epc == ffffffff818f9a6c, ra == ffffffff813ad7d0
	... ...
	Call Trace:
	[<ffffffff818f9a6c>] __raw_copy_from_user+0x48/0x2fc
	[<ffffffff813ad7d0>] cp_statx+0x1a0/0x1e0
	[<ffffffff813ae528>] do_statx_fd+0xa8/0x118
	[<ffffffff813ae670>] sys_statx+0xd8/0xf8
	[<ffffffff81156cc8>] syscall_common+0x34/0x58

So ignore those relocs on our own to fix the issue.

Fixes: 6f2c2f93a190 ("scripts/sorttable: Remove unneeded Elf_Rel")
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/boot/tools/relocs.c b/arch/mips/boot/tools/relocs.c
index a88d66c46d7f7882b6e5986f037cac972d00d436..9863e1d5c62e3dea3a42dbea150debc401fb2d9c 100644 (file)
--- a/arch/mips/boot/tools/relocs.c
+++ b/arch/mips/boot/tools/relocs.c
@@ -468,6 +468,8 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
                        Elf_Sym *sym, const char *symname))
 {
        int i;
+       struct section *extab_sec = sec_lookup("__ex_table");
+       int extab_index = extab_sec ? extab_sec - secs : -1;
 
        /* Walk through the relocations */
        for (i = 0; i < ehdr.e_shnum; i++) {
@@ -480,6 +482,9 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
                if (sec->shdr.sh_type != SHT_REL_TYPE)
                        continue;
 
+               if (sec->shdr.sh_info == extab_index)
+                       continue;
+
                sec_symtab  = sec->link;
                sec_applies = &secs[sec->shdr.sh_info];
                if (!(sec_applies->shdr.sh_flags & SHF_ALLOC))