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authorKees Cook <kees+treewide@kernel.org>2026-09-02 15:31:14 -0700
committerKees Cook <kees@kernel.org>2026-09-04 21:37:00 -0700
commit3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d (patch)
treec65086f9bdcd48c6360fb7cb4598bca084da1f32 /arch/riscv/lib/strlen.S
downloadlinux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.tar.gz
linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.zip
treewide: refresh kmalloc_obj() conversionsgrafted
This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook <kees+treewide@kernel.org>
Diffstat (limited to 'arch/riscv/lib/strlen.S')
-rw-r--r--arch/riscv/lib/strlen.S133
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/riscv/lib/strlen.S b/arch/riscv/lib/strlen.S
new file mode 100644
index 000000000..e7736ccda
--- /dev/null
+++ b/arch/riscv/lib/strlen.S
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/alternative-macros.h>
+#include <asm/hwcap.h>
+
+/* int strlen(const char *s) */
+SYM_FUNC_START(strlen)
+
+ __ALTERNATIVE_CFG("nop", "j strlen_zbb", 0, RISCV_ISA_EXT_ZBB,
+ IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB))
+
+ /*
+ * Returns
+ * a0 - string length
+ *
+ * Parameters
+ * a0 - String to measure
+ *
+ * Clobbers:
+ * t0, t1
+ */
+ addi t1, a0, -1
+1:
+ addi t1, t1, 1
+ lbu t0, 0(t1)
+ bnez t0, 1b
+ sub a0, t1, a0
+ ret
+
+/*
+ * Variant of strlen using the ZBB extension if available
+ */
+#if defined(CONFIG_RISCV_ISA_ZBB) && defined(CONFIG_TOOLCHAIN_HAS_ZBB)
+strlen_zbb:
+
+#ifdef CONFIG_CPU_BIG_ENDIAN
+# define CZ clz
+# define SHIFT sll
+#else
+# define CZ ctz
+# define SHIFT srl
+#endif
+
+.option push
+.option arch,+zbb
+
+ /*
+ * Returns
+ * a0 - string length
+ *
+ * Parameters
+ * a0 - String to measure
+ *
+ * Clobbers
+ * t0, t1, t2, t3
+ */
+
+ /* Number of irrelevant bytes in the first word. */
+ andi t2, a0, SZREG-1
+
+ /* Align pointer. */
+ andi t0, a0, -SZREG
+
+ li t3, SZREG
+ sub t3, t3, t2
+ slli t2, t2, 3
+
+ /* Get the first word. */
+ REG_L t1, 0(t0)
+
+ /*
+ * Shift away the partial data we loaded to remove the irrelevant bytes
+ * preceding the string with the effect of adding NUL bytes at the
+ * end of the string's first word.
+ */
+ SHIFT t1, t1, t2
+
+ /* Convert non-NUL into 0xff and NUL into 0x00. */
+ orc.b t1, t1
+
+ /* Convert non-NUL into 0x00 and NUL into 0xff. */
+ not t1, t1
+
+ /*
+ * Search for the first set bit (corresponding to a NUL byte in the
+ * original chunk).
+ */
+ CZ t1, t1
+
+ /*
+ * The first chunk is special: compare against the number
+ * of valid bytes in this chunk.
+ */
+ srli a0, t1, 3
+ bgtu t3, a0, 2f
+
+ /* Prepare for the word comparison loop. */
+ addi t2, t0, SZREG
+ li t3, -1
+
+ /*
+ * Our critical loop is 4 instructions and processes data in
+ * 4 byte or 8 byte chunks.
+ */
+ .p2align 3
+1:
+ REG_L t1, SZREG(t0)
+ addi t0, t0, SZREG
+ orc.b t1, t1
+ beq t1, t3, 1b
+
+ not t1, t1
+ CZ t1, t1
+ srli t1, t1, 3
+
+ /* Get number of processed bytes. */
+ sub t2, t0, t2
+
+ /* Add number of characters in the first word. */
+ add a0, a0, t2
+
+ /* Add number of characters in the last word. */
+ add a0, a0, t1
+2:
+ ret
+
+.option pop
+#endif
+SYM_FUNC_END(strlen)
+SYM_FUNC_ALIAS(__pi_strlen, strlen)
+EXPORT_SYMBOL(strlen)