QEMU-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: r.bolshakov@yadro.com, j@getutm.app
Subject: [PATCH v2 16/29] tcg: Replace region.end with region.total_size
Date: Sun, 14 Mar 2021 15:27:11 -0600
Message-ID: <20210314212724.1917075-17-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210314212724.1917075-1-richard.henderson@linaro.org>

A size is easier to work with than an end point,
particularly during initial buffer allocation.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/region.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/tcg/region.c b/tcg/region.c
index ae22308290..8e4dd0480b 100644
--- a/tcg/region.c
+++ b/tcg/region.c
@@ -48,7 +48,7 @@ struct tcg_region_state {
     /* fields set at init time */
     void *start;
     void *start_aligned;
-    void *end;
+    size_t total_size; /* size of entire buffer */
     size_t n;
     size_t size; /* size of one region */
     size_t stride; /* .size + guard size */
@@ -279,7 +279,7 @@ static void tcg_region_bounds(size_t curr_region, void **pstart, void **pend)
         start = region.start;
     }
     if (curr_region == region.n - 1) {
-        end = region.end;
+        end = region.start_aligned + region.total_size;
     }
 
     *pstart = start;
@@ -813,8 +813,8 @@ static bool alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
  */
 void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
 {
-    void *buf, *aligned;
-    size_t size;
+    void *buf, *aligned, *end;
+    size_t total_size;
     size_t page_size;
     size_t region_size;
     size_t n_regions;
@@ -827,19 +827,20 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
     assert(ok);
 
     buf = tcg_init_ctx.code_gen_buffer;
-    size = tcg_init_ctx.code_gen_buffer_size;
+    total_size = tcg_init_ctx.code_gen_buffer_size;
     page_size = qemu_real_host_page_size;
     n_regions = tcg_n_regions(max_cpus);
 
     /* The first region will be 'aligned - buf' bytes larger than the others */
     aligned = QEMU_ALIGN_PTR_UP(buf, page_size);
-    g_assert(aligned < tcg_init_ctx.code_gen_buffer + size);
+    g_assert(aligned < tcg_init_ctx.code_gen_buffer + total_size);
+
     /*
      * Make region_size a multiple of page_size, using aligned as the start.
      * As a result of this we might end up with a few extra pages at the end of
      * the buffer; we will assign those to the last region.
      */
-    region_size = (size - (aligned - buf)) / n_regions;
+    region_size = (total_size - (aligned - buf)) / n_regions;
     region_size = QEMU_ALIGN_DOWN(region_size, page_size);
 
     /* A region must have at least 2 pages; one code, one guard */
@@ -853,9 +854,11 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
     region.start = buf;
     region.start_aligned = aligned;
     /* page-align the end, since its last page will be a guard page */
-    region.end = QEMU_ALIGN_PTR_DOWN(buf + size, page_size);
+    end = QEMU_ALIGN_PTR_DOWN(buf + total_size, page_size);
     /* account for that last guard page */
-    region.end -= page_size;
+    end -= page_size;
+    total_size = end - aligned;
+    region.total_size = total_size;
 
     /* set guard pages */
     splitwx_diff = tcg_splitwx_diff;
@@ -893,7 +896,7 @@ void tcg_region_prologue_set(TCGContext *s)
 
     /* Register the balance of the buffer with gdb. */
     tcg_register_jit(tcg_splitwx_to_rx(region.start),
-                     region.end - region.start);
+                     region.start_aligned + region.total_size - region.start);
 }
 
 /*
@@ -934,8 +937,10 @@ size_t tcg_code_capacity(void)
 
     /* no need for synchronization; these variables are set at init time */
     guard_size = region.stride - region.size;
-    capacity = region.end + guard_size - region.start;
-    capacity -= region.n * (guard_size + TCG_HIGHWATER);
+    capacity = region.total_size;
+    capacity -= (region.n - 1) * guard_size;
+    capacity -= region.n * TCG_HIGHWATER;
+
     return capacity;
 }
 
-- 
2.25.1



  parent reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-14 21:26 [PATCH v2 00/29] tcg: Workaround macOS 11.2 mprotect bug Richard Henderson
2021-03-14 21:26 ` [PATCH v2 01/29] meson: Split out tcg/meson.build Richard Henderson
2021-03-15 23:09   ` Roman Bolshakov
2021-03-14 21:26 ` [PATCH v2 02/29] meson: Split out fpu/meson.build Richard Henderson
2021-03-15 23:10   ` Roman Bolshakov
2021-03-14 21:26 ` [PATCH v2 03/29] tcg: Re-order tcg_region_init vs tcg_prologue_init Richard Henderson
2021-03-15 23:37   ` Roman Bolshakov
2021-03-16 14:57     ` Richard Henderson
2021-03-14 21:26 ` [PATCH v2 04/29] tcg: Remove error return from tcg_region_initial_alloc__locked Richard Henderson
2021-03-14 21:27 ` [PATCH v2 05/29] tcg: Split out tcg_region_initial_alloc Richard Henderson
2021-03-14 21:27 ` [PATCH v2 06/29] tcg: Split out tcg_region_prologue_set Richard Henderson
2021-03-14 21:27 ` [PATCH v2 07/29] tcg: Split out region.c Richard Henderson
2021-03-14 21:27 ` [PATCH v2 08/29] accel/tcg: Inline cpu_gen_init Richard Henderson
2021-03-14 21:27 ` [PATCH v2 09/29] accel/tcg: Move alloc_code_gen_buffer to tcg/region.c Richard Henderson
2021-03-14 21:27 ` [PATCH v2 10/29] accel/tcg: Rename tcg_init to tcg_init_machine Richard Henderson
2021-03-14 21:27 ` [PATCH v2 11/29] tcg: Create tcg_init Richard Henderson
2021-03-14 21:27 ` [PATCH v2 12/29] accel/tcg: Merge tcg_exec_init into tcg_init_machine Richard Henderson
2021-03-14 21:27 ` [PATCH v2 13/29] accel/tcg: Pass down max_cpus to tcg_init Richard Henderson
2021-03-14 21:27 ` [PATCH v2 14/29] tcg: Introduce tcg_max_ctxs Richard Henderson
2021-03-14 21:27 ` [PATCH v2 15/29] tcg: Move MAX_CODE_GEN_BUFFER_SIZE to tcg-target.h Richard Henderson
2021-03-14 21:27 ` Richard Henderson [this message]
2021-03-14 21:27 ` [PATCH v2 17/29] tcg: Rename region.start to region.after_prologue Richard Henderson
2021-03-14 21:27 ` [PATCH v2 18/29] tcg: Tidy tcg_n_regions Richard Henderson
2021-03-14 21:27 ` [PATCH v2 19/29] tcg: Tidy split_cross_256mb Richard Henderson
2021-03-14 21:27 ` [PATCH v2 20/29] tcg: Move in_code_gen_buffer and tests to region.c Richard Henderson
2021-03-14 21:27 ` [PATCH v2 21/29] tcg: Allocate code_gen_buffer into struct tcg_region_state Richard Henderson
2021-03-14 21:27 ` [PATCH v2 22/29] tcg: Return the map protection from alloc_code_gen_buffer Richard Henderson
2021-03-14 22:04   ` Philippe Mathieu-Daudé
2021-03-14 21:27 ` [PATCH v2 23/29] tcg: Sink qemu_madvise call to common code Richard Henderson
2021-03-14 21:27 ` [PATCH v2 24/29] tcg: Do not set guard pages in the rx buffer Richard Henderson
2021-03-14 21:27 ` [PATCH v2 25/29] util/osdep: Add qemu_mprotect_rw Richard Henderson
2021-03-14 21:27 ` [PATCH v2 26/29] tcg: Round the tb_size default from qemu_get_host_physmem Richard Henderson
2021-03-14 21:27 ` [PATCH v2 27/29] tcg: Merge buffer protection and guard page protection Richard Henderson
2021-03-14 21:27 ` [PATCH v2 28/29] tcg: When allocating for !splitwx, begin with PROT_NONE Richard Henderson
2021-03-14 21:27 ` [PATCH v2 29/29] tcg: Move tcg_init_ctx and tcg_ctx from accel/tcg/ Richard Henderson
2021-03-14 22:00   ` Philippe Mathieu-Daudé
2021-03-14 22:12 ` [PATCH v2 00/29] tcg: Workaround macOS 11.2 mprotect bug no-reply
2021-03-15 23:08 ` Roman Bolshakov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210314212724.1917075-17-richard.henderson@linaro.org \
    --to=richard.henderson@linaro.org \
    --cc=j@getutm.app \
    --cc=qemu-devel@nongnu.org \
    --cc=r.bolshakov@yadro.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

QEMU-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/qemu-devel/0 qemu-devel/git/0.git
	git clone --mirror https://lore.kernel.org/qemu-devel/1 qemu-devel/git/1.git
	git clone --mirror https://lore.kernel.org/qemu-devel/2 qemu-devel/git/2.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 qemu-devel qemu-devel/ https://lore.kernel.org/qemu-devel \
		qemu-devel@nongnu.org
	public-inbox-index qemu-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.nongnu.qemu-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git