[PATCH v4 2/6] scripts/sorttable: Have mcount rela sort use direct values

Steven Rostedt
2025-02-17T15:34:33Z

The mcount_loc sorting for when the values are stored in the Elf_Rela
entries uses the compare_extable() function to do the compares in the
qsort(). That function does handle byte swapping if the machine being
compiled for is a different endian than the host machine. But the
sort_relocs() function sorts an array that pulled in the values from the
Elf_Rela section and has already done the swapping.

Create two new compare functions that will sort the direct values. One
will sort 32 bit values and the other will sort the 64 bit value. One of
these will be assigned to a compare_values function pointer and that will
be used for sorting the Elf_Rela mcount values.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
scripts/sorttable.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 4a34c275123e..f62a91d8af0a 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -552,6 +552,28 @@ static void *sort_orctable(void *arg)

#ifdef MCOUNT_SORT_ENABLED

+static int compare_values_64(const void *a, const void *b)
+{
+ uint64_t av = *(uint64_t *)a;
+ uint64_t bv = *(uint64_t *)b;
+
+ if (av < bv)
+ return -1;
+ return av > bv;
+}
+
+static int compare_values_32(const void *a, const void *b)
+{
+ uint32_t av = *(uint32_t *)a;
+ uint32_t bv = *(uint32_t *)b;
+
+ if (av < bv)
+ return -1;
+ return av > bv;
+}
+
+static int (*compare_values)(const void *a, const void *b);
+
/* Only used for sorting mcount table */
static void rela_write_addend(Elf_Rela *rela, uint64_t val)
{
@@ -583,6 +605,8 @@ static void *sort_relocs(Elf_Ehdr *ehdr, uint64_t start_loc, uint64_t size)
void *vals;
void *ptr;

+ compare_values = long_size == 4 ? compare_values_32 : compare_values_64;
+
shdr_start = (Elf_Shdr *)((char *)ehdr + ehdr_shoff(ehdr));
shentsize = ehdr_shentsize(ehdr);

@@ -640,7 +664,7 @@ static void *sort_relocs(Elf_Ehdr *ehdr, uint64_t start_loc, uint64_t size)
}
}
count = ptr - vals;
- qsort(vals, count / long_size, long_size, compare_extable);
+ qsort(vals, count / long_size, long_size, compare_values);

ptr = vals;
for (int i = 0; i < shnum; i++) {
--
2.47.2