[PATCH 4/4] scripts/sorttable: Allow matches to functions before function entry
Steven Rostedt
rostedt at goodmis.org
Tue Feb 25 10:20:08 PST 2025
From: Steven Rostedt <rostedt at goodmis.org>
ARM 64 uses -fpatchable-function-entry=4,2 which adds padding before the
function and the addresses in the mcount_loc point there instead of the
function entry that is returned by nm. In order to find a function from nm
to make sure it's not an unused weak function, the entries in the
mcount_loc section needs to match the entries from nm. Since it can be an
instruction before the entry, add a before_func variable that ARM 64 can
set to 8, and if the mcount_loc entry is within 8 bytes of the nm function
entry, then it will be considered a match.
Fixes: ef378c3b82338 ("scripts/sorttable: Zero out weak functions in mcount_loc table")
Tested-by: Nathan Chancellor <nathan at kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt at goodmis.org>
---
scripts/sorttable.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 07ad8116bc8d..7b4b3714b1af 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -611,13 +611,16 @@ static int add_field(uint64_t addr, uint64_t size)
return 0;
}
+/* Used for when mcount/fentry is before the function entry */
+static int before_func;
+
/* Only return match if the address lies inside the function size */
static int cmp_func_addr(const void *K, const void *A)
{
uint64_t key = *(const uint64_t *)K;
const struct func_info *a = A;
- if (key < a->addr)
+ if (key + before_func < a->addr)
return -1;
return key >= a->addr + a->size;
}
@@ -1253,6 +1256,8 @@ static int do_file(char const *const fname, void *addr)
#ifdef MCOUNT_SORT_ENABLED
sort_reloc = true;
rela_type = 0x403;
+ /* arm64 uses patchable function entry placing before function */
+ before_func = 8;
#endif
/* fallthrough */
case EM_386:
--
2.47.2
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