From: Ard Biesheuvel <[email protected]> The original crc32c code used a place-relative jump table but with a slightly awkward use of two separate symbols. To help objtool, this was replaced with a bog-standard position dependent jump table call, which was subsequently tweaked to use a RIP-relative reference to the table, but still populate it with absolute 64-bit references.
Given that objtool will need to be taught about the jump table idiom that compilers use when running with -fpie enabled, let's update the jump table in the crc32c code once again to use this standard idiom, where the jump table carries 32-bit references relative to the start of the table, and the destination address can be obtained by adding the two. Signed-off-by: Ard Biesheuvel <[email protected]> --- arch/x86/crypto/crc32c-pcl-intel-asm_64.S | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S index bbcff1fb78cb..45b005935194 100644 --- a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S +++ b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S @@ -53,7 +53,7 @@ .endm .macro JMPTBL_ENTRY i -.quad .Lcrc_\i +.long .Lcrc_\i - jump_table .endm .macro JNC_LESS_THAN j @@ -169,7 +169,8 @@ SYM_FUNC_START(crc_pcl) ## branch into array leaq jump_table(%rip), %bufp - mov (%bufp,%rax,8), %bufp + movslq (%bufp,%rax,4), len + addq len, %bufp JMP_NOSPEC bufp ################################################################ -- 2.47.0.rc0.187.ge670bccf7e-goog
