From: "Borislav Petkov (AMD)" <bp@alien8.de>

The tool uses the 16 least significant bits of the CPUID leaf as an
index into its array of CPUID function field descriptions.

However, when that index is non-existent, it uses the same, truncated
index to report it, which is wrong:

$ kcpuid -l 0x80000034
  ERR: invalid input index (0x34)

Use the original index number in the error message.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
 tools/arch/x86/kcpuid/kcpuid.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
index 416f5b35dd8f..24b7d017ec2c 100644
--- a/tools/arch/x86/kcpuid/kcpuid.c
+++ b/tools/arch/x86/kcpuid/kcpuid.c
@@ -517,15 +517,16 @@ static void show_range(struct cpuid_range *range)
 static inline struct cpuid_func *index_to_func(u32 index)
 {
 	struct cpuid_range *range;
+	u32 func_idx;
 
 	range = (index & 0x80000000) ? leafs_ext : leafs_basic;
-	index &= 0x7FFFFFFF;
+	func_idx = index & 0xffff;
 
-	if (((index & 0xFFFF) + 1) > (u32)range->nr) {
+	if ((func_idx + 1) > (u32)range->nr) {
 		printf("ERR: invalid input index (0x%x)\n", index);
 		return NULL;
 	}
-	return &range->funcs[index];
+	return &range->funcs[func_idx];
 }
 
 static void show_info(void)
-- 
2.35.1

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     0150d1bfbedf29d7473ae458815781488f62d11d
Gitweb:        https://git.kernel.org/tip/0150d1bfbedf29d7473ae458815781488f62d11d
Author:        Borislav Petkov (AMD) <bp@alien8.de>
AuthorDate:    Wed, 26 Apr 2023 11:41:07 +02:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 08 May 2023 15:50:27 +02:00

tools/x86/kcpuid: Dump the correct CPUID function in error

The tool uses the 16 least significant bits of the CPUID leaf as an
index into its array of CPUID function field descriptions.

However, when that index is non-existent, it uses the same, truncated
index to report it, which is wrong:

$ kcpuid -l 0x80000034
  ERR: invalid input index (0x34)

Use the original index number in the error message.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230426094107.27348-1-bp@alien8.de
---
 tools/arch/x86/kcpuid/kcpuid.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
index 416f5b3..24b7d01 100644
--- a/tools/arch/x86/kcpuid/kcpuid.c
+++ b/tools/arch/x86/kcpuid/kcpuid.c
@@ -517,15 +517,16 @@ static void show_range(struct cpuid_range *range)
 static inline struct cpuid_func *index_to_func(u32 index)
 {
 	struct cpuid_range *range;
+	u32 func_idx;
 
 	range = (index & 0x80000000) ? leafs_ext : leafs_basic;
-	index &= 0x7FFFFFFF;
+	func_idx = index & 0xffff;
 
-	if (((index & 0xFFFF) + 1) > (u32)range->nr) {
+	if ((func_idx + 1) > (u32)range->nr) {
 		printf("ERR: invalid input index (0x%x)\n", index);
 		return NULL;
 	}
-	return &range->funcs[index];
+	return &range->funcs[func_idx];
 }
 
 static void show_info(void)