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[undi] Read TSC only when profiling

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Avoid using the "rdtsc" instruction unless profiling is enabled.  This
allows the non-debug build of the UNDI driver to be used on a CPU such
as a 486 that does not support the TSC.

Reported-by: Nikolai Zhubr <n-a-zhubr@yandex.ru>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2021-05-12 10:55:17 +01:00
parent 05fcf1a2f0
commit a6a8bb1a9a
1 changed files with 9 additions and 2 deletions
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11
src/arch/x86/drivers/net/undinet.c
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@@ -104,6 +104,13 @@ static union u_PXENV_ANY __bss16 ( undinet_params );
SEGOFF16_t __bss16 ( undinet_entry_point );
#define undinet_entry_point __use_data16 ( undinet_entry_point )
/* Read TSC in real mode only when profiling */
#if PROFILING
#define RDTSC_IF_PROFILING "rdtsc\n\t"
#else
#define RDTSC_IF_PROFILING ""
#endif
/** IRQ profiler */
static struct profiler undinet_irq_profiler __profiler =
{ .name = "undinet.irq" };
@@ -288,14 +295,14 @@ static int undinet_call ( struct undi_nic *undinic, unsigned int function,
*/
profile_start ( &profiler->total );
__asm__ __volatile__ ( REAL_CODE ( "pushl %%ebp\n\t" /* gcc bug */
"rdtsc\n\t"
RDTSC_IF_PROFILING
"pushl %%eax\n\t"
"pushw %%es\n\t"
"pushw %%di\n\t"
"pushw %%bx\n\t"
"lcall *undinet_entry_point\n\t"
"movw %%ax, %%bx\n\t"
"rdtsc\n\t"
RDTSC_IF_PROFILING
"addw $6, %%sp\n\t"
"popl %%edx\n\t"
"popl %%ebp\n\t" /* gcc bug */ )