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Re: [Qemu-devel] [PATCH v2] translate-all: use bitmap helpers for PageDe
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v2] translate-all: use bitmap helpers for PageDesc's bitmap |
Date: |
Wed, 22 Apr 2015 22:30:23 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 22/04/2015 18:53, Emilio G. Cota wrote:
> Here we have an open-coded byte-based bitmap implementation.
> Get rid of it since there's a ulong-based implementation to be
> used by all code.
>
> Signed-off-by: Emilio G. Cota <address@hidden>
> ---
> translate-all.c | 40 +++++++---------------------------------
> 1 file changed, 7 insertions(+), 33 deletions(-)
>
> diff --git a/translate-all.c b/translate-all.c
> index acf792c..9592a3b 100644
> --- a/translate-all.c
> +++ b/translate-all.c
> @@ -59,6 +59,7 @@
>
> #include "exec/cputlb.h"
> #include "translate-all.h"
> +#include "qemu/bitmap.h"
> #include "qemu/timer.h"
>
> //#define DEBUG_TB_INVALIDATE
> @@ -79,7 +80,7 @@ typedef struct PageDesc {
> /* in order to optimize self modifying code, we count the number
> of lookups we do to a given page to use a bitmap */
> unsigned int code_write_count;
> - uint8_t *code_bitmap;
> + unsigned long *code_bitmap;
> #if defined(CONFIG_USER_ONLY)
> unsigned long flags;
> #endif
> @@ -964,39 +965,12 @@ void tb_phys_invalidate(TranslationBlock *tb,
> tb_page_addr_t page_addr)
> tcg_ctx.tb_ctx.tb_phys_invalidate_count++;
> }
>
> -static inline void set_bits(uint8_t *tab, int start, int len)
> -{
> - int end, mask, end1;
> -
> - end = start + len;
> - tab += start >> 3;
> - mask = 0xff << (start & 7);
> - if ((start & ~7) == (end & ~7)) {
> - if (start < end) {
> - mask &= ~(0xff << (end & 7));
> - *tab |= mask;
> - }
> - } else {
> - *tab++ |= mask;
> - start = (start + 8) & ~7;
> - end1 = end & ~7;
> - while (start < end1) {
> - *tab++ = 0xff;
> - start += 8;
> - }
> - if (start < end) {
> - mask = ~(0xff << (end & 7));
> - *tab |= mask;
> - }
> - }
> -}
> -
> static void build_page_bitmap(PageDesc *p)
> {
> int n, tb_start, tb_end;
> TranslationBlock *tb;
>
> - p->code_bitmap = g_malloc0(TARGET_PAGE_SIZE / 8);
> + p->code_bitmap = bitmap_new(TARGET_PAGE_SIZE);
>
> tb = p->first_tb;
> while (tb != NULL) {
> @@ -1015,7 +989,7 @@ static void build_page_bitmap(PageDesc *p)
> tb_start = 0;
> tb_end = ((tb->pc + tb->size) & ~TARGET_PAGE_MASK);
> }
> - set_bits(p->code_bitmap, tb_start, tb_end - tb_start);
> + bitmap_set(p->code_bitmap, tb_start, tb_end - tb_start);
> tb = tb->page_next[n];
> }
> }
> @@ -1205,7 +1179,6 @@ void tb_invalidate_phys_page_range(tb_page_addr_t
> start, tb_page_addr_t end,
> void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len)
> {
> PageDesc *p;
> - int offset, b;
>
> #if 0
> if (1) {
> @@ -1221,8 +1194,9 @@ void tb_invalidate_phys_page_fast(tb_page_addr_t start,
> int len)
> return;
> }
> if (p->code_bitmap) {
> - offset = start & ~TARGET_PAGE_MASK;
> - b = p->code_bitmap[offset >> 3] >> (offset & 7);
> + int nr = start & ~TARGET_PAGE_MASK;
This should be unsigned, otherwise the compiler might not make
BIT_WORD(nr) a simple right shift (maybe it can see that nr > 0 thanks
to the AND, but in principle x / 32 is not the same as x >> 5 if x is
signed).
> + int b = p->code_bitmap[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG - 1));
And this should be unsigned long.
Otherwise looks good.
Paolo
> +
> if (b & ((1 << len) - 1)) {
> goto do_invalidate;
> }
>