Commit c10d52d6 authored by Armin Wolf's avatar Armin Wolf Committed by Guenter Roeck
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hwmon: (dell-smm) Improve assembly code 



The new assembly code works on both 32 bit and 64 bit
cpus and allows for more compiler optimisations.
Since clang runs out of registers on 32 bit x86 when
using CC_OUT, we need to execute "setc" ourself.
Also modify the debug message so we can still see
the result (eax) when the carry flag was set.

Tested with 32 bit and 64 bit kernels on a Dell Inspiron 3505.

Signed-off-by: default avatarArmin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20220220190851.17965-1-W_Armin@gmx.de


[groeck: Rebased to v5.19-rc3]
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 4a235369

drivers/hwmon/dell-smm-hwmon.c

+18 −60
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ struct smm_regs { 
	unsigned int edx;

	unsigned int esi;

	unsigned int edi;

} __packed;

};



static const char * const temp_labels[] = {

	"CPU",
@@ -175,77 +175,35 @@ static int i8k_smm_func(void *par) 
	struct smm_regs *regs = par;

	int eax = regs->eax;

	int ebx = regs->ebx;

	unsigned char carry;

	long long duration;

	int rc;



	/* SMM requires CPU 0 */

	if (smp_processor_id() != 0)

		return -EBUSY;



#if defined(CONFIG_X86_64)

	asm volatile("pushq %%rax\n\t"

		"movl 0(%%rax),%%edx\n\t"

		"pushq %%rdx\n\t"

		"movl 4(%%rax),%%ebx\n\t"

		"movl 8(%%rax),%%ecx\n\t"

		"movl 12(%%rax),%%edx\n\t"

		"movl 16(%%rax),%%esi\n\t"

		"movl 20(%%rax),%%edi\n\t"

		"popq %%rax\n\t"

		"out %%al,$0xb2\n\t"

	asm volatile("out %%al,$0xb2\n\t"

		     "out %%al,$0x84\n\t"

		"xchgq %%rax,(%%rsp)\n\t"

		"movl %%ebx,4(%%rax)\n\t"

		"movl %%ecx,8(%%rax)\n\t"

		"movl %%edx,12(%%rax)\n\t"

		"movl %%esi,16(%%rax)\n\t"

		"movl %%edi,20(%%rax)\n\t"

		"popq %%rdx\n\t"

		"movl %%edx,0(%%rax)\n\t"

		"pushfq\n\t"

		"popq %%rax\n\t"

		"andl $1,%%eax\n"

		: "=a"(rc)

		:    "a"(regs)

		:    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");

#else

	asm volatile("pushl %%eax\n\t"

	    "movl 0(%%eax),%%edx\n\t"

	    "push %%edx\n\t"

	    "movl 4(%%eax),%%ebx\n\t"

	    "movl 8(%%eax),%%ecx\n\t"

	    "movl 12(%%eax),%%edx\n\t"

	    "movl 16(%%eax),%%esi\n\t"

	    "movl 20(%%eax),%%edi\n\t"

	    "popl %%eax\n\t"

	    "out %%al,$0xb2\n\t"

	    "out %%al,$0x84\n\t"

	    "xchgl %%eax,(%%esp)\n\t"

	    "movl %%ebx,4(%%eax)\n\t"

	    "movl %%ecx,8(%%eax)\n\t"

	    "movl %%edx,12(%%eax)\n\t"

	    "movl %%esi,16(%%eax)\n\t"

	    "movl %%edi,20(%%eax)\n\t"

	    "popl %%edx\n\t"

	    "movl %%edx,0(%%eax)\n\t"

	    "lahf\n\t"

	    "shrl $8,%%eax\n\t"

	    "andl $1,%%eax\n"

	    : "=a"(rc)

	    :    "a"(regs)

	    :    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");

#endif

	if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)

		rc = -EINVAL;

		     "setc %0\n"

		     : "=mr" (carry),

		       "+a" (regs->eax),

		       "+b" (regs->ebx),

		       "+c" (regs->ecx),

		       "+d" (regs->edx),

		       "+S" (regs->esi),

		       "+D" (regs->edi));



	duration = ktime_us_delta(ktime_get(), calltime);

	pr_debug("smm(0x%.4x 0x%.4x) = 0x%.4x  (took %7lld usecs)\n", eax, ebx,

		 (rc ? 0xffff : regs->eax & 0xffff), duration);

	pr_debug("smm(0x%.4x 0x%.4x) = 0x%.4x carry: %d (took %7lld usecs)\n",

		 eax, ebx, regs->eax & 0xffff, carry, duration);



	if (duration > DELL_SMM_MAX_DURATION)

		pr_warn_once("SMM call took %lld usecs!\n", duration);



	return rc;

	if (carry || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)

		return -EINVAL;



	return 0;

}



/*