Re: [PATCH 1/3] scripts/recordmcount.pl: Fix RISC-V regex for clang

From: Fangrui Song
Date: Thu Mar 25 2021 - 19:37:44 EST


On 2021-03-25, Nathan Chancellor wrote:
Clang can generate R_RISCV_CALL_PLT relocations to _mcount:

$ llvm-objdump -dr build/riscv/init/main.o | rg mcount
000000000000000e: R_RISCV_CALL_PLT _mcount
000000000000004e: R_RISCV_CALL_PLT _mcount

After this, the __start_mcount_loc section is properly generated and
function tracing still works.


R_RISCV_CALL_PLT can replace R_RISCV_CALL in all use cases.
R_RISCV_CALL can/may be deprecated:
https://github.com/ClangBuiltLinux/linux/issues/1331#issuecomment-802468296

Reviewed-by: Fangrui Song <maskray@xxxxxxxxxx>


Cc: stable@xxxxxxxxxxxxxxx
Link: https://github.com/ClangBuiltLinux/linux/issues/1331
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
---
scripts/recordmcount.pl | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 867860ea57da..a36df04cfa09 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -392,7 +392,7 @@ if ($arch eq "x86_64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
} elsif ($arch eq "riscv") {
$function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
- $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL\\s_mcount\$";
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_mcount\$";
$type = ".quad";
$alignment = 2;
} elsif ($arch eq "nds32") {
--
2.31.0

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