[RFC,v3,6/7] scripts/sorttable: Add ORC unwind tables sort concurrently
diff mbox series

Message ID 20191115064750.47888-7-shile.zhang@linux.alibaba.com
State New
Headers show
Series
  • Speed booting by sorting ORC unwind tables at build time
Related show

Commit Message

Shile Zhang Nov. 15, 2019, 6:47 a.m. UTC
ORC unwinder have two tables, .orc_unwind_ip and .orc_unwind, which
needs sorted for binary search. To sort it at build time can save more
CPU cycles help to speed up kernel booting.

Add the ORC tables sorting in a sperated thread helps to avoid more link
cost of kernel building.

Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
---
 scripts/Makefile    |   5 ++
 scripts/sorttable.h | 214 ++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 213 insertions(+), 6 deletions(-)

Comments

Peter Zijlstra Nov. 15, 2019, 9:07 a.m. UTC | #1
On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:

> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
> +/* ORC unwinder only support X86_64 */
> +#include <errno.h>
> +#include <pthread.h>
> +#include <linux/types.h>
> +
> +#define ORC_REG_UNDEFINED	0
> +#define ERRSTRING_MAXSZ		256
> +
> +struct orc_entry {
> +	s16		sp_offset;
> +	s16		bp_offset;
> +	unsigned	sp_reg:4;
> +	unsigned	bp_reg:4;
> +	unsigned	type:2;
> +	unsigned	end:1;
> +} __attribute__((packed));
> +
> +struct orctable_info {
> +	size_t	orc_size;
> +	size_t	orc_ip_size;
> +} orctable;

There's ./arch/x86/include/asm/orc_types.h for this. Please don't
duplicate. objtool uses that same header.

> +/**
> + * sort - sort an array of elements
> + * @base: pointer to data to sort
> + * @num: number of elements
> + * @size: size of each element
> + * @cmp_func: pointer to comparison function
> + * @swap_func: pointer to swap function
> + *
> + * This function does a heapsort on the given array. You may provide a
> + * swap_func function optimized to your element type.
> + *
> + * Sorting time is O(n log n) both on average and worst-case. While
> + * qsort is about 20% faster on average, it suffers from exploitable
> + * O(n*n) worst-case behavior and extra memory requirements that make
> + * it less suitable for kernel use.
> + *
> + * This code token out of /lib/sort.c.
> + */
> +static void sort(void *base, size_t num, size_t size,
> +	  int (*cmp_func)(const void *, const void *),
> +	  void (*swap_func)(void *, void *, int size))
> +{
> +	/* pre-scale counters for performance */
> +	int i = (num/2 - 1) * size, n = num * size, c, r;
> +
> +	/* heapify */
> +	for ( ; i >= 0; i -= size) {
> +		for (r = i; r * 2 + size < n; r  = c) {
> +			c = r * 2 + size;
> +			if (c < n - size &&
> +					cmp_func(base + c, base + c + size) < 0)
> +				c += size;
> +			if (cmp_func(base + r, base + c) >= 0)
> +				break;
> +			swap_func(base + r, base + c, size);
> +		}
> +	}
> +
> +	/* sort */
> +	for (i = n - size; i > 0; i -= size) {
> +		swap_func(base, base + i, size);
> +		for (r = 0; r * 2 + size < i; r = c) {
> +			c = r * 2 + size;
> +			if (c < i - size &&
> +					cmp_func(base + c, base + c + size) < 0)
> +				c += size;
> +			if (cmp_func(base + r, base + c) >= 0)
> +				break;
> +			swap_func(base + r, base + c, size);
> +		}
> +	}
> +}

Do we really need to copy the heapsort implementation? That is, why not
use libc's qsort() ? This is userspace after all.
Peter Zijlstra Nov. 15, 2019, 9:19 a.m. UTC | #2
On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:

> @@ -141,21 +306,44 @@ static int do_sort(Elf_Ehdr *ehdr,
>  		if (r(&s->sh_type) == SHT_SYMTAB_SHNDX)
>  			symtab_shndx = (Elf32_Word *)((const char *)ehdr +
>  						      _r(&s->sh_offset));
> -	}
>  
> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
> +		/* locate the ORC unwind tables */
> +		if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
> +			orctable.orc_ip_size = s->sh_size;
> +			g_orc_ip_table = (int *)((void *)ehdr +
> +						   s->sh_offset);
> +		}
> +		if (!strcmp(secstrings + idx, ".orc_unwind")) {
> +			orctable.orc_size = s->sh_size;
> +			g_orc_table = (struct orc_entry *)((void *)ehdr +
> +							     s->sh_offset);
> +		}
> +#endif
> +	} /* for loop */
> +
> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)

Maybe something like:

	if (g_orc_table && g_orc_ip_table) {
		 if (pthread_create(...))
		...
	} else if (g_orc_table || g_orc_up_table) {
		fprintf(stderr, "incomplete ORC tables...\n");
	}

> +	/* create thread to sort ORC unwind tables concurrently */
> +	if (pthread_create(&orc_sort_thread, NULL, sort_orctable, &orctable)) {
> +		fprintf(stderr,
> +			"pthread_create orc_sort_thread failed '%s': %s\n",
> +			strerror(errno), fname);
> +		goto out;
> +	}
> +#endif
>  	if (!extab_sec) {
>  		fprintf(stderr,	"no __ex_table in file: %s\n", fname);
> -		return -1;
> +		goto out;
>  	}
>  
>  	if (!symtab_sec) {
>  		fprintf(stderr,	"no .symtab in file: %s\n", fname);
> -		return -1;
> +		goto out;
>  	}
>  
>  	if (!strtab_sec) {
>  		fprintf(stderr,	"no .strtab in file: %s\n", fname);
> -		return -1;
> +		goto out;
>  	}
>  
>  	extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
> @@ -192,7 +380,7 @@ static int do_sort(Elf_Ehdr *ehdr,
>  		fprintf(stderr,
>  			"no main_extable_sort_needed symbol in file: %s\n",
>  			fname);
> -		return -1;
> +		goto out;
>  	}
>  
>  	sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
> @@ -205,6 +393,20 @@ static int do_sort(Elf_Ehdr *ehdr,
>  
>  	/* extable has been sorted, clear the flag */
>  	w(0, sort_needed_loc);
> +	rc = 0;
>  
> -	return 0;
> +out:
> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
> +	{ /* to avoid gcc warning about declaration */
> +	void *retval = NULL;

and then here:

	if (orc_sort_thread) {
		void *retval = NULL;
		pthread_join(...);
		...
	}

> +
> +	/* wait for ORC tables sort done */
> +	pthread_join(orc_sort_thread, &retval);
> +	if (retval) {
> +		fprintf(stderr, "%s in file: %s\n", (char *)retval, fname);
> +		rc = -1;
> +	}
> +	}
> +#endif
> +	return rc;
>  }
Shile Zhang Nov. 15, 2019, 9:43 a.m. UTC | #3
On 2019/11/15 17:07, Peter Zijlstra wrote:
> On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:
>
>> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>> +/* ORC unwinder only support X86_64 */
>> +#include <errno.h>
>> +#include <pthread.h>
>> +#include <linux/types.h>
>> +
>> +#define ORC_REG_UNDEFINED	0
>> +#define ERRSTRING_MAXSZ		256
>> +
>> +struct orc_entry {
>> +	s16		sp_offset;
>> +	s16		bp_offset;
>> +	unsigned	sp_reg:4;
>> +	unsigned	bp_reg:4;
>> +	unsigned	type:2;
>> +	unsigned	end:1;
>> +} __attribute__((packed));
>> +
>> +struct orctable_info {
>> +	size_t	orc_size;
>> +	size_t	orc_ip_size;
>> +} orctable;
> There's ./arch/x86/include/asm/orc_types.h for this. Please don't
> duplicate. objtool uses that same header.
Good catch! Thanks for your kindly reminder! I'll remove it.
>> +/**
>> + * sort - sort an array of elements
>> + * @base: pointer to data to sort
>> + * @num: number of elements
>> + * @size: size of each element
>> + * @cmp_func: pointer to comparison function
>> + * @swap_func: pointer to swap function
>> + *
>> + * This function does a heapsort on the given array. You may provide a
>> + * swap_func function optimized to your element type.
>> + *
>> + * Sorting time is O(n log n) both on average and worst-case. While
>> + * qsort is about 20% faster on average, it suffers from exploitable
>> + * O(n*n) worst-case behavior and extra memory requirements that make
>> + * it less suitable for kernel use.
>> + *
>> + * This code token out of /lib/sort.c.
>> + */
>> +static void sort(void *base, size_t num, size_t size,
>> +	  int (*cmp_func)(const void *, const void *),
>> +	  void (*swap_func)(void *, void *, int size))
>> +{
>> +	/* pre-scale counters for performance */
>> +	int i = (num/2 - 1) * size, n = num * size, c, r;
>> +
>> +	/* heapify */
>> +	for ( ; i >= 0; i -= size) {
>> +		for (r = i; r * 2 + size < n; r  = c) {
>> +			c = r * 2 + size;
>> +			if (c < n - size &&
>> +					cmp_func(base + c, base + c + size) < 0)
>> +				c += size;
>> +			if (cmp_func(base + r, base + c) >= 0)
>> +				break;
>> +			swap_func(base + r, base + c, size);
>> +		}
>> +	}
>> +
>> +	/* sort */
>> +	for (i = n - size; i > 0; i -= size) {
>> +		swap_func(base, base + i, size);
>> +		for (r = 0; r * 2 + size < i; r = c) {
>> +			c = r * 2 + size;
>> +			if (c < i - size &&
>> +					cmp_func(base + c, base + c + size) < 0)
>> +				c += size;
>> +			if (cmp_func(base + r, base + c) >= 0)
>> +				break;
>> +			swap_func(base + r, base + c, size);
>> +		}
>> +	}
>> +}
> Do we really need to copy the heapsort implementation? That is, why not
> use libc's qsort() ? This is userspace after all.

Yes, I think qsort is better choice than copy-paste here. But qsort does 
not support customized swap func, which is needed for ORC unwind swap 
two tables together.
I think it's hard to do with qsort, so I used sort same with original 
orc unwind table sort.
Shile Zhang Nov. 15, 2019, 9:45 a.m. UTC | #4
On 2019/11/15 17:19, Peter Zijlstra wrote:
> On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:
>
>> @@ -141,21 +306,44 @@ static int do_sort(Elf_Ehdr *ehdr,
>>   		if (r(&s->sh_type) == SHT_SYMTAB_SHNDX)
>>   			symtab_shndx = (Elf32_Word *)((const char *)ehdr +
>>   						      _r(&s->sh_offset));
>> -	}
>>   
>> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>> +		/* locate the ORC unwind tables */
>> +		if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
>> +			orctable.orc_ip_size = s->sh_size;
>> +			g_orc_ip_table = (int *)((void *)ehdr +
>> +						   s->sh_offset);
>> +		}
>> +		if (!strcmp(secstrings + idx, ".orc_unwind")) {
>> +			orctable.orc_size = s->sh_size;
>> +			g_orc_table = (struct orc_entry *)((void *)ehdr +
>> +							     s->sh_offset);
>> +		}
>> +#endif
>> +	} /* for loop */
>> +
>> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
> Maybe something like:
>
> 	if (g_orc_table && g_orc_ip_table) {
> 		 if (pthread_create(...))
> 		...
> 	} else if (g_orc_table || g_orc_up_table) {
> 		fprintf(stderr, "incomplete ORC tables...\n");
> 	}
>
>> +	/* create thread to sort ORC unwind tables concurrently */
>> +	if (pthread_create(&orc_sort_thread, NULL, sort_orctable, &orctable)) {
>> +		fprintf(stderr,
>> +			"pthread_create orc_sort_thread failed '%s': %s\n",
>> +			strerror(errno), fname);
>> +		goto out;
>> +	}
>> +#endif
>>   	if (!extab_sec) {
>>   		fprintf(stderr,	"no __ex_table in file: %s\n", fname);
>> -		return -1;
>> +		goto out;
>>   	}
>>   
>>   	if (!symtab_sec) {
>>   		fprintf(stderr,	"no .symtab in file: %s\n", fname);
>> -		return -1;
>> +		goto out;
>>   	}
>>   
>>   	if (!strtab_sec) {
>>   		fprintf(stderr,	"no .strtab in file: %s\n", fname);
>> -		return -1;
>> +		goto out;
>>   	}
>>   
>>   	extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
>> @@ -192,7 +380,7 @@ static int do_sort(Elf_Ehdr *ehdr,
>>   		fprintf(stderr,
>>   			"no main_extable_sort_needed symbol in file: %s\n",
>>   			fname);
>> -		return -1;
>> +		goto out;
>>   	}
>>   
>>   	sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
>> @@ -205,6 +393,20 @@ static int do_sort(Elf_Ehdr *ehdr,
>>   
>>   	/* extable has been sorted, clear the flag */
>>   	w(0, sort_needed_loc);
>> +	rc = 0;
>>   
>> -	return 0;
>> +out:
>> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>> +	{ /* to avoid gcc warning about declaration */
>> +	void *retval = NULL;
> and then here:
>
> 	if (orc_sort_thread) {
> 		void *retval = NULL;
> 		pthread_join(...);
> 		...
> 	}


Thank you for your kindly advice! I'll change it in next version.

>> +
>> +	/* wait for ORC tables sort done */
>> +	pthread_join(orc_sort_thread, &retval);
>> +	if (retval) {
>> +		fprintf(stderr, "%s in file: %s\n", (char *)retval, fname);
>> +		rc = -1;
>> +	}
>> +	}
>> +#endif
>> +	return rc;
>>   }
Peter Zijlstra Nov. 15, 2019, 10:33 a.m. UTC | #5
On Fri, Nov 15, 2019 at 05:43:49PM +0800, Shile Zhang wrote:
> On 2019/11/15 17:07, Peter Zijlstra wrote:
> > On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:

> > > +/**
> > > + * sort - sort an array of elements
> > > + * @base: pointer to data to sort
> > > + * @num: number of elements
> > > + * @size: size of each element
> > > + * @cmp_func: pointer to comparison function
> > > + * @swap_func: pointer to swap function
> > > + *
> > > + * This function does a heapsort on the given array. You may provide a
> > > + * swap_func function optimized to your element type.
> > > + *
> > > + * Sorting time is O(n log n) both on average and worst-case. While
> > > + * qsort is about 20% faster on average, it suffers from exploitable
> > > + * O(n*n) worst-case behavior and extra memory requirements that make
> > > + * it less suitable for kernel use.
> > > + *
> > > + * This code token out of /lib/sort.c.
> > > + */
> > > +static void sort(void *base, size_t num, size_t size,
> > > +	  int (*cmp_func)(const void *, const void *),
> > > +	  void (*swap_func)(void *, void *, int size))
> > > +{

> > > +}

> > Do we really need to copy the heapsort implementation? That is, why not
> > use libc's qsort() ? This is userspace after all.
> 
> Yes, I think qsort is better choice than copy-paste here. But qsort does not
> support customized swap func, which is needed for ORC unwind swap two tables
> together.
> I think it's hard to do with qsort, so I used sort same with original orc
> unwind table sort.

Urgh, you're right. That's unforunate.
Andy Lutomirski Nov. 15, 2019, 5:24 p.m. UTC | #6
> On Nov 15, 2019, at 1:43 AM, Shile Zhang <shile.zhang@linux.alibaba.com> wrote:
> 
> 
> 
>> On 2019/11/15 17:07, Peter Zijlstra wrote:
>>> On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:
>>> 
>>> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>>> +/* ORC unwinder only support X86_64 */
>>> +#include <errno.h>
>>> +#include <pthread.h>
>>> +#include <linux/types.h>
>>> +
>>> +#define ORC_REG_UNDEFINED    0
>>> +#define ERRSTRING_MAXSZ        256
>>> +
>>> +struct orc_entry {
>>> +    s16        sp_offset;
>>> +    s16        bp_offset;
>>> +    unsigned    sp_reg:4;
>>> +    unsigned    bp_reg:4;
>>> +    unsigned    type:2;
>>> +    unsigned    end:1;
>>> +} __attribute__((packed));
>>> +
>>> +struct orctable_info {
>>> +    size_t    orc_size;
>>> +    size_t    orc_ip_size;
>>> +} orctable;
>> There's ./arch/x86/include/asm/orc_types.h for this. Please don't
>> duplicate. objtool uses that same header.
> Good catch! Thanks for your kindly reminder! I'll remove it.
>>> +/**
>>> + * sort - sort an array of elements
>>> + * @base: pointer to data to sort
>>> + * @num: number of elements
>>> + * @size: size of each element
>>> + * @cmp_func: pointer to comparison function
>>> + * @swap_func: pointer to swap function
>>> + *
>>> + * This function does a heapsort on the given array. You may provide a
>>> + * swap_func function optimized to your element type.
>>> + *
>>> + * Sorting time is O(n log n) both on average and worst-case. While
>>> + * qsort is about 20% faster on average, it suffers from exploitable
>>> + * O(n*n) worst-case behavior and extra memory requirements that make
>>> + * it less suitable for kernel use.
>>> + *
>>> + * This code token out of /lib/sort.c.
>>> + */
>>> +static void sort(void *base, size_t num, size_t size,
>>> +      int (*cmp_func)(const void *, const void *),
>>> +      void (*swap_func)(void *, void *, int size))
>>> +{
>>> +    /* pre-scale counters for performance */
>>> +    int i = (num/2 - 1) * size, n = num * size, c, r;
>>> +
>>> +    /* heapify */
>>> +    for ( ; i >= 0; i -= size) {
>>> +        for (r = i; r * 2 + size < n; r  = c) {
>>> +            c = r * 2 + size;
>>> +            if (c < n - size &&
>>> +                    cmp_func(base + c, base + c + size) < 0)
>>> +                c += size;
>>> +            if (cmp_func(base + r, base + c) >= 0)
>>> +                break;
>>> +            swap_func(base + r, base + c, size);
>>> +        }
>>> +    }
>>> +
>>> +    /* sort */
>>> +    for (i = n - size; i > 0; i -= size) {
>>> +        swap_func(base, base + i, size);
>>> +        for (r = 0; r * 2 + size < i; r = c) {
>>> +            c = r * 2 + size;
>>> +            if (c < i - size &&
>>> +                    cmp_func(base + c, base + c + size) < 0)
>>> +                c += size;
>>> +            if (cmp_func(base + r, base + c) >= 0)
>>> +                break;
>>> +            swap_func(base + r, base + c, size);
>>> +        }
>>> +    }
>>> +}
>> Do we really need to copy the heapsort implementation? That is, why not
>> use libc's qsort() ? This is userspace after all.
> 
> Yes, I think qsort is better choice than copy-paste here. But qsort does not support customized swap func, which is needed for ORC unwind swap two tables together.
> I think it's hard to do with qsort, so I used sort same with original orc unwind table sort.

One solution is to make an array of indices 0, 1, 2, etc, and sort that using a comparison function that compares i,j by actually comparing source[i], source[j]. (Or use pointers, but indices are probably faster on a 64-bit machine if you can use 32-bit indices.) Then, after sorting, permute the original array using the now-sorted indices. In the case where swapping is expensive, this is actually faster, since it does exactly n moves instead of O(n log n).

>
Shile Zhang Nov. 18, 2019, 11:43 a.m. UTC | #7
On 2019/11/16 01:24, Andy Lutomirski wrote:
>> On Nov 15, 2019, at 1:43 AM, Shile Zhang <shile.zhang@linux.alibaba.com> wrote:
>>
>> 
>>
>>> On 2019/11/15 17:07, Peter Zijlstra wrote:
>>>> On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:
>>>>
>>>> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>>>> +/* ORC unwinder only support X86_64 */
>>>> +#include <errno.h>
>>>> +#include <pthread.h>
>>>> +#include <linux/types.h>
>>>> +
>>>> +#define ORC_REG_UNDEFINED    0
>>>> +#define ERRSTRING_MAXSZ        256
>>>> +
>>>> +struct orc_entry {
>>>> +    s16        sp_offset;
>>>> +    s16        bp_offset;
>>>> +    unsigned    sp_reg:4;
>>>> +    unsigned    bp_reg:4;
>>>> +    unsigned    type:2;
>>>> +    unsigned    end:1;
>>>> +} __attribute__((packed));
>>>> +
>>>> +struct orctable_info {
>>>> +    size_t    orc_size;
>>>> +    size_t    orc_ip_size;
>>>> +} orctable;
>>> There's ./arch/x86/include/asm/orc_types.h for this. Please don't
>>> duplicate. objtool uses that same header.
>> Good catch! Thanks for your kindly reminder! I'll remove it.
>>>> +/**
>>>> + * sort - sort an array of elements
>>>> + * @base: pointer to data to sort
>>>> + * @num: number of elements
>>>> + * @size: size of each element
>>>> + * @cmp_func: pointer to comparison function
>>>> + * @swap_func: pointer to swap function
>>>> + *
>>>> + * This function does a heapsort on the given array. You may provide a
>>>> + * swap_func function optimized to your element type.
>>>> + *
>>>> + * Sorting time is O(n log n) both on average and worst-case. While
>>>> + * qsort is about 20% faster on average, it suffers from exploitable
>>>> + * O(n*n) worst-case behavior and extra memory requirements that make
>>>> + * it less suitable for kernel use.
>>>> + *
>>>> + * This code token out of /lib/sort.c.
>>>> + */
>>>> +static void sort(void *base, size_t num, size_t size,
>>>> +      int (*cmp_func)(const void *, const void *),
>>>> +      void (*swap_func)(void *, void *, int size))
>>>> +{
>>>> +    /* pre-scale counters for performance */
>>>> +    int i = (num/2 - 1) * size, n = num * size, c, r;
>>>> +
>>>> +    /* heapify */
>>>> +    for ( ; i >= 0; i -= size) {
>>>> +        for (r = i; r * 2 + size < n; r  = c) {
>>>> +            c = r * 2 + size;
>>>> +            if (c < n - size &&
>>>> +                    cmp_func(base + c, base + c + size) < 0)
>>>> +                c += size;
>>>> +            if (cmp_func(base + r, base + c) >= 0)
>>>> +                break;
>>>> +            swap_func(base + r, base + c, size);
>>>> +        }
>>>> +    }
>>>> +
>>>> +    /* sort */
>>>> +    for (i = n - size; i > 0; i -= size) {
>>>> +        swap_func(base, base + i, size);
>>>> +        for (r = 0; r * 2 + size < i; r = c) {
>>>> +            c = r * 2 + size;
>>>> +            if (c < i - size &&
>>>> +                    cmp_func(base + c, base + c + size) < 0)
>>>> +                c += size;
>>>> +            if (cmp_func(base + r, base + c) >= 0)
>>>> +                break;
>>>> +            swap_func(base + r, base + c, size);
>>>> +        }
>>>> +    }
>>>> +}
>>> Do we really need to copy the heapsort implementation? That is, why not
>>> use libc's qsort() ? This is userspace after all.
>> Yes, I think qsort is better choice than copy-paste here. But qsort does not support customized swap func, which is needed for ORC unwind swap two tables together.
>> I think it's hard to do with qsort, so I used sort same with original orc unwind table sort.
> One solution is to make an array of indices 0, 1, 2, etc, and sort that using a comparison function that compares i,j by actually comparing source[i], source[j]. (Or use pointers, but indices are probably faster on a 64-bit machine if you can use 32-bit indices.) Then, after sorting, permute the original array using the now-sorted indices. In the case where swapping is expensive, this is actually faster, since it does exactly n moves instead of O(n log n).

Hi, Andy,

Thanks for your suggestion!
It's works, qsort is faster than heap sort, sort time down from 70ms to 
20ms.

I'll update in next version.
Thanks again!

Patch
diff mbox series

diff --git a/scripts/Makefile b/scripts/Makefile
index 658d201f7f8b..06e9f4f5ea93 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -26,6 +26,11 @@  HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
 HOSTLDLIBS_sign-file = -lcrypto
 HOSTLDLIBS_extract-cert = -lcrypto
 
+ifdef CONFIG_UNWINDER_ORC
+HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED
+HOSTLDLIBS_sorttable = -lpthread
+endif
+
 always		:= $(hostprogs-y) $(hostprogs-m)
 
 # The following hostprogs-y programs are only build on demand
diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index 82589ff90e25..a75f8b4a125f 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -4,6 +4,14 @@ 
  *
  * Copyright 2011 - 2012 Cavium, Inc.
  *
+ * Added ORC unwind tables sort support, and other updates:
+ * Copyright (C) 1999-2019 Alibaba Group Holding Limited. by:
+ * Shile Zhang <shile.zhang@linux.alibaba.com>
+ *
+ * Some of code was taken out of /lib/sort.c, and
+ * arch/x86/kernel/unwind_orc.c written by:
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ *
  * Some of this code was taken out of recordmcount.h written by:
  *
  * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
@@ -75,6 +83,162 @@ 
 # define _w			w
 #endif
 
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+/* ORC unwinder only support X86_64 */
+#include <errno.h>
+#include <pthread.h>
+#include <linux/types.h>
+
+#define ORC_REG_UNDEFINED	0
+#define ERRSTRING_MAXSZ		256
+
+struct orc_entry {
+	s16		sp_offset;
+	s16		bp_offset;
+	unsigned	sp_reg:4;
+	unsigned	bp_reg:4;
+	unsigned	type:2;
+	unsigned	end:1;
+} __attribute__((packed));
+
+struct orctable_info {
+	size_t	orc_size;
+	size_t	orc_ip_size;
+} orctable;
+
+char g_errstring[ERRSTRING_MAXSZ];
+int *g_orc_ip_table;
+struct orc_entry *g_orc_table;
+pthread_t orc_sort_thread;
+
+/**
+ * sort - sort an array of elements
+ * @base: pointer to data to sort
+ * @num: number of elements
+ * @size: size of each element
+ * @cmp_func: pointer to comparison function
+ * @swap_func: pointer to swap function
+ *
+ * This function does a heapsort on the given array. You may provide a
+ * swap_func function optimized to your element type.
+ *
+ * Sorting time is O(n log n) both on average and worst-case. While
+ * qsort is about 20% faster on average, it suffers from exploitable
+ * O(n*n) worst-case behavior and extra memory requirements that make
+ * it less suitable for kernel use.
+ *
+ * This code token out of /lib/sort.c.
+ */
+static void sort(void *base, size_t num, size_t size,
+	  int (*cmp_func)(const void *, const void *),
+	  void (*swap_func)(void *, void *, int size))
+{
+	/* pre-scale counters for performance */
+	int i = (num/2 - 1) * size, n = num * size, c, r;
+
+	/* heapify */
+	for ( ; i >= 0; i -= size) {
+		for (r = i; r * 2 + size < n; r  = c) {
+			c = r * 2 + size;
+			if (c < n - size &&
+					cmp_func(base + c, base + c + size) < 0)
+				c += size;
+			if (cmp_func(base + r, base + c) >= 0)
+				break;
+			swap_func(base + r, base + c, size);
+		}
+	}
+
+	/* sort */
+	for (i = n - size; i > 0; i -= size) {
+		swap_func(base, base + i, size);
+		for (r = 0; r * 2 + size < i; r = c) {
+			c = r * 2 + size;
+			if (c < i - size &&
+					cmp_func(base + c, base + c + size) < 0)
+				c += size;
+			if (cmp_func(base + r, base + c) >= 0)
+				break;
+			swap_func(base + r, base + c, size);
+		}
+	}
+}
+
+static inline unsigned long orc_ip(const int *ip)
+{
+	return (unsigned long)ip + *ip;
+}
+
+static void orc_sort_swap(void *_a, void *_b, int size)
+{
+	struct orc_entry *orc_a, *orc_b;
+	struct orc_entry orc_tmp;
+	int *a = _a, *b = _b, tmp;
+	int delta = _b - _a;
+
+	/* Swap the .orc_unwind_ip entries: */
+	tmp = *a;
+	*a = *b + delta;
+	*b = tmp - delta;
+
+	/* Swap the corresponding .orc_unwind entries: */
+	orc_a = g_orc_table + (a - g_orc_ip_table);
+	orc_b = g_orc_table + (b - g_orc_ip_table);
+	orc_tmp = *orc_a;
+	*orc_a = *orc_b;
+	*orc_b = orc_tmp;
+}
+
+static int orc_sort_cmp(const void *_a, const void *_b)
+{
+	struct orc_entry *orc_a;
+	const int *a = _a, *b = _b;
+	unsigned long a_val = orc_ip(a);
+	unsigned long b_val = orc_ip(b);
+
+	if (a_val > b_val)
+		return 1;
+	if (a_val < b_val)
+		return -1;
+
+	/*
+	 * The "weak" section terminator entries need to always be on the left
+	 * to ensure the lookup code skips them in favor of real entries.
+	 * These terminator entries exist to handle any gaps created by
+	 * whitelisted .o files which didn't get objtool generation.
+	 */
+	orc_a = g_orc_table + (a - g_orc_ip_table);
+	return orc_a->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1;
+}
+
+static void *sort_orctable(void *arg)
+{
+	struct orctable_info *orcptr = (struct orctable_info *)arg;
+	unsigned int num_entries;
+
+	if (!g_orc_ip_table || !g_orc_table) {
+		snprintf(g_errstring, ERRSTRING_MAXSZ,
+			 "cannot find ORC unwind tables");
+		pthread_exit(g_errstring);
+	}
+
+	num_entries = orcptr->orc_ip_size / sizeof(int);
+
+	if (orcptr->orc_ip_size % sizeof(int) != 0 ||
+	    orcptr->orc_size % sizeof(struct orc_entry) != 0 ||
+	    num_entries != orcptr->orc_size / sizeof(struct orc_entry)) {
+		snprintf(g_errstring, ERRSTRING_MAXSZ,
+			"wrong ORC unwind table entries number");
+		pthread_exit(g_errstring);
+	}
+
+	sort(g_orc_ip_table, num_entries, sizeof(int),
+	     orc_sort_cmp, orc_sort_swap);
+
+	pthread_exit(NULL);
+}
+#endif
+
 static int compare_extable(const void *a, const void *b)
 {
 	Elf_Addr av = _r(a);
@@ -91,6 +255,7 @@  static int do_sort(Elf_Ehdr *ehdr,
 		   char const *const fname,
 		   table_sort_t custom_sort)
 {
+	int rc = -1;
 	Elf_Shdr *s, *shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
 	Elf_Shdr *strtab_sec = NULL;
 	Elf_Shdr *symtab_sec = NULL;
@@ -141,21 +306,44 @@  static int do_sort(Elf_Ehdr *ehdr,
 		if (r(&s->sh_type) == SHT_SYMTAB_SHNDX)
 			symtab_shndx = (Elf32_Word *)((const char *)ehdr +
 						      _r(&s->sh_offset));
-	}
 
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+		/* locate the ORC unwind tables */
+		if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
+			orctable.orc_ip_size = s->sh_size;
+			g_orc_ip_table = (int *)((void *)ehdr +
+						   s->sh_offset);
+		}
+		if (!strcmp(secstrings + idx, ".orc_unwind")) {
+			orctable.orc_size = s->sh_size;
+			g_orc_table = (struct orc_entry *)((void *)ehdr +
+							     s->sh_offset);
+		}
+#endif
+	} /* for loop */
+
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+	/* create thread to sort ORC unwind tables concurrently */
+	if (pthread_create(&orc_sort_thread, NULL, sort_orctable, &orctable)) {
+		fprintf(stderr,
+			"pthread_create orc_sort_thread failed '%s': %s\n",
+			strerror(errno), fname);
+		goto out;
+	}
+#endif
 	if (!extab_sec) {
 		fprintf(stderr,	"no __ex_table in file: %s\n", fname);
-		return -1;
+		goto out;
 	}
 
 	if (!symtab_sec) {
 		fprintf(stderr,	"no .symtab in file: %s\n", fname);
-		return -1;
+		goto out;
 	}
 
 	if (!strtab_sec) {
 		fprintf(stderr,	"no .strtab in file: %s\n", fname);
-		return -1;
+		goto out;
 	}
 
 	extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
@@ -192,7 +380,7 @@  static int do_sort(Elf_Ehdr *ehdr,
 		fprintf(stderr,
 			"no main_extable_sort_needed symbol in file: %s\n",
 			fname);
-		return -1;
+		goto out;
 	}
 
 	sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
@@ -205,6 +393,20 @@  static int do_sort(Elf_Ehdr *ehdr,
 
 	/* extable has been sorted, clear the flag */
 	w(0, sort_needed_loc);
+	rc = 0;
 
-	return 0;
+out:
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+	{ /* to avoid gcc warning about declaration */
+	void *retval = NULL;
+
+	/* wait for ORC tables sort done */
+	pthread_join(orc_sort_thread, &retval);
+	if (retval) {
+		fprintf(stderr, "%s in file: %s\n", (char *)retval, fname);
+		rc = -1;
+	}
+	}
+#endif
+	return rc;
 }