Use grub_divmod64() for the 64-bit modulus to prevent creation of
__umoddi3() calls on 32-bit platforms.
Signed-off-by: Gary Lin <g...@suse.com>
---
conf/Makefile.extra-dist | 1 +
.../12-kdf-use-grub_divmod64.patch | 78 +++++++++++++++++++
2 files changed, 79 insertions(+)
create mode 100644
grub-core/lib/libgcrypt-patches/12-kdf-use-grub_divmod64.patch
diff --git a/conf/Makefile.extra-dist b/conf/Makefile.extra-dist
index abd4227e7..5d9ff91e9 100644
--- a/conf/Makefile.extra-dist
+++ b/conf/Makefile.extra-dist
@@ -46,6 +46,7 @@ EXTRA_DIST +=
grub-core/lib/libgcrypt-patches/08_sexp_leak.patch
EXTRA_DIST += grub-core/lib/libgcrypt-patches/09-blake2b-hash-buffers.patch
EXTRA_DIST += grub-core/lib/libgcrypt-patches/10-kdf-use-GPG-errs.patch
EXTRA_DIST +=
grub-core/lib/libgcrypt-patches/11-kdf-remove-unsupported-kdfs.patch
+EXTRA_DIST += grub-core/lib/libgcrypt-patches/12-kdf-use-grub_divmod64.patch
EXTRA_DIST +=
grub-core/lib/libtasn1-patches/0001-libtasn1-disable-code-not-needed-in-grub.patch
EXTRA_DIST +=
grub-core/lib/libtasn1-patches/0002-libtasn1-replace-strcat-with-strcpy-in-_asn1_str_cat.patch
diff --git a/grub-core/lib/libgcrypt-patches/12-kdf-use-grub_divmod64.patch
b/grub-core/lib/libgcrypt-patches/12-kdf-use-grub_divmod64.patch
new file mode 100644
index 000000000..f6e1251ae
--- /dev/null
+++ b/grub-core/lib/libgcrypt-patches/12-kdf-use-grub_divmod64.patch
@@ -0,0 +1,78 @@
+From 232133d5672a89f5e5a45116171e802c1ebab2e7 Mon Sep 17 00:00:00 2001
+From: Gary Lin <g...@suse.com>
+Date: Mon, 25 Aug 2025 16:01:45 +0800
+Subject: [PATCH 4/4] libgcrypt/kdf: Fix 64-bit modulus on 32-bit platforms
+
+Use grub_divmod64() for the 64-bit modulus to prevent creation of
+__umoddi3() calls on 32-bit platforms.
+
+Signed-off-by: Gary Lin <g...@suse.com>
+---
+ grub-core/lib/libgcrypt-grub/cipher/kdf.c | 16 ++++++++++++----
+ 1 file changed, 12 insertions(+), 4 deletions(-)
+
+diff --git a/grub-core/lib/libgcrypt-grub/cipher/kdf.c
b/grub-core/lib/libgcrypt-grub/cipher/kdf.c
+index 6e825d3e8..e0a1b2901 100644
+--- a/grub-core/lib/libgcrypt-grub/cipher/kdf.c
++++ b/grub-core/lib/libgcrypt-grub/cipher/kdf.c
+@@ -370,6 +370,7 @@ index_alpha (argon2_ctx_t a, const struct
argon2_thread_data *t,
+ u32 reference_area_size;
+ u64 relative_position;
+ u32 start_position;
++ u64 remainder;
+
+ if (t->pass == 0)
+ {
+@@ -406,7 +407,8 @@ index_alpha (argon2_ctx_t a, const struct
argon2_thread_data *t,
+ ? 0
+ : (t->slice + 1) * a->segment_length;
+
+- return (start_position + relative_position) % a->lane_length;
++ grub_divmod64 (start_position + relative_position, a->lane_length,
&remainder);
++ return remainder;
+ }
+
+ static void
+@@ -420,6 +422,7 @@ argon2_compute_segment (void *priv)
+ u64 input_block[1024/sizeof (u64)];
+ u64 address_block[1024/sizeof (u64)];
+ u64 *random_block = NULL;
++ u64 remainder;
+
+ if (a->hash_type == GCRY_KDF_ARGON2I
+ || (a->hash_type == GCRY_KDF_ARGON2ID && t->pass == 0 && t->slice < 2))
+@@ -444,7 +447,8 @@ argon2_compute_segment (void *priv)
+ i = 0;
+
+ curr_offset = t->lane * a->lane_length + t->slice * a->segment_length + i;
+- if ((curr_offset % a->lane_length))
++ grub_divmod64 (curr_offset, a->lane_length, &remainder);
++ if (remainder)
+ prev_offset = curr_offset - 1;
+ else
+ prev_offset = curr_offset + a->lane_length - 1;
+@@ -454,7 +458,8 @@ argon2_compute_segment (void *priv)
+ u64 *ref_block, *curr_block;
+ u64 rand64;
+
+- if ((curr_offset % a->lane_length) == 1)
++ grub_divmod64 (curr_offset, a->lane_length, &remainder);
++ if (remainder == 1)
+ prev_offset = curr_offset - 1;
+
+ if (random_block)
+@@ -470,7 +475,10 @@ argon2_compute_segment (void *priv)
+ if (t->pass == 0 && t->slice == 0)
+ ref_lane = t->lane;
+ else
+- ref_lane = (rand64 >> 32) % a->lanes;
++ {
++ grub_divmod64 (rand64 >> 32, a->lanes, &remainder);
++ ref_lane = remainder;
++ }
+
+ ref_index = index_alpha (a, t, i, (rand64 & 0xffffffff),
+ ref_lane == t->lane);
+--
+2.43.0
+
--
2.43.0
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