[PATCH v3 04/20] tools/x86/kcpuid: Save CPUID output in an array

From: Ahmed S. Darwish
Date: Mon Mar 24 2025 - 10:21:47 EST


For each CPUID leaf/subleaf query, save the output in an output[] array
instead of spelling it out using EAX to EDX variables.

This allows the CPUID output to be accessed programmatically instead of
calling decode_bits() four times. Loop-based access also allows "kcpuid
--detail" to print the correct output register names in next commit.

Signed-off-by: Ahmed S. Darwish <darwi@xxxxxxxxxxxxx>
---
tools/arch/x86/kcpuid/kcpuid.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
index b760c5730c89..dfabc0a56507 100644
--- a/tools/arch/x86/kcpuid/kcpuid.c
+++ b/tools/arch/x86/kcpuid/kcpuid.c
@@ -51,7 +51,7 @@ static const char * const reg_names[] = {
struct subleaf {
u32 index;
u32 sub;
- u32 eax, ebx, ecx, edx;
+ u32 output[NR_REGS];
struct reg_desc info[NR_REGS];
};

@@ -119,11 +119,11 @@ static void leaf_print_raw(struct subleaf *leaf)
if (leaf->sub == 0)
printf("0x%08x: subleafs:\n", leaf->index);

- printf(" %2d: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n",
- leaf->sub, leaf->eax, leaf->ebx, leaf->ecx, leaf->edx);
+ printf(" %2d: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n", leaf->sub,
+ leaf->output[0], leaf->output[1], leaf->output[2], leaf->output[3]);
} else {
- printf("0x%08x: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n",
- leaf->index, leaf->eax, leaf->ebx, leaf->ecx, leaf->edx);
+ printf("0x%08x: EAX=0x%08x, EBX=0x%08x, ECX=0x%08x, EDX=0x%08x\n", leaf->index,
+ leaf->output[0], leaf->output[1], leaf->output[2], leaf->output[3]);
}
}

@@ -163,10 +163,10 @@ static bool cpuid_store(struct cpuid_range *range, u32 f, int subleaf,

leaf->index = f;
leaf->sub = subleaf;
- leaf->eax = a;
- leaf->ebx = b;
- leaf->ecx = c;
- leaf->edx = d;
+ leaf->output[R_EAX] = a;
+ leaf->output[R_EBX] = b;
+ leaf->output[R_ECX] = c;
+ leaf->output[R_EDX] = d;

return false;
}
@@ -490,10 +490,8 @@ static void show_leaf(struct subleaf *leaf)
leaf->index, leaf->sub);
}

- decode_bits(leaf->eax, &leaf->info[R_EAX], R_EAX);
- decode_bits(leaf->ebx, &leaf->info[R_EBX], R_EBX);
- decode_bits(leaf->ecx, &leaf->info[R_ECX], R_ECX);
- decode_bits(leaf->edx, &leaf->info[R_EDX], R_EDX);
+ for (int i = R_EAX; i < NR_REGS; i++)
+ decode_bits(leaf->output[i], &leaf->info[i], i);

if (!show_raw && show_details)
printf("\n");
--
2.48.1