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tcg: Replace region.end with region.total_size 

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

Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
master
Richard Henderson 2021-03-10 10:35:05 -06:00
parent 26a75d12d3
commit 77bd7fd125
1 changed files with 18 additions and 12 deletions
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30
tcg/region.c
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@ -48,10 +48,10 @@ struct tcg_region_state {
/* fields set at init time */ /* fields set at init time */
void *start; void *start;
void *start_aligned; void *start_aligned;
void *end;
size_t n; size_t n;
size_t size; /* size of one region */ size_t size; /* size of one region */
size_t stride; /* .size + guard size */ size_t stride; /* .size + guard size */
size_t total_size; /* size of entire buffer, >= n * stride */
/* fields protected by the lock */ /* fields protected by the lock */
size_t current; /* current region index */ size_t current; /* current region index */
@ -278,8 +278,9 @@ static void tcg_region_bounds(size_t curr_region, void **pstart, void **pend)
if (curr_region == 0) { if (curr_region == 0) {
start = region.start; start = region.start;
} }
/* The final region may have a few extra pages due to earlier rounding. */
if (curr_region == region.n - 1) { if (curr_region == region.n - 1) {
end = region.end; end = region.start_aligned + region.total_size;
} }
*pstart = start; *pstart = start;
@ -817,8 +818,8 @@ 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 tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
{ {
void *buf, *aligned; void *buf, *aligned, *end;
size_t size; size_t total_size;
size_t page_size; size_t page_size;
size_t region_size; size_t region_size;
size_t n_regions; size_t n_regions;
@ -830,19 +831,20 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
assert(ok); assert(ok);
buf = tcg_init_ctx.code_gen_buffer; 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; page_size = qemu_real_host_page_size;
n_regions = tcg_n_regions(max_cpus); n_regions = tcg_n_regions(max_cpus);
/* The first region will be 'aligned - buf' bytes larger than the others */ /* The first region will be 'aligned - buf' bytes larger than the others */
aligned = QEMU_ALIGN_PTR_UP(buf, page_size); 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. * 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 * 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. * 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); region_size = QEMU_ALIGN_DOWN(region_size, page_size);
/* A region must have at least 2 pages; one code, one guard */ /* A region must have at least 2 pages; one code, one guard */
@ -856,9 +858,11 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
region.start = buf; region.start = buf;
region.start_aligned = aligned; region.start_aligned = aligned;
/* page-align the end, since its last page will be a guard page */ /* 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 */ /* 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 in the rw buffer, as that's the one into which * Set guard pages in the rw buffer, as that's the one into which
@ -899,7 +903,7 @@ void tcg_region_prologue_set(TCGContext *s)
/* Register the balance of the buffer with gdb. */ /* Register the balance of the buffer with gdb. */
tcg_register_jit(tcg_splitwx_to_rx(region.start), tcg_register_jit(tcg_splitwx_to_rx(region.start),
region.end - region.start); region.start_aligned + region.total_size - region.start);
} }
/* /*
@ -940,8 +944,10 @@ size_t tcg_code_capacity(void)
/* no need for synchronization; these variables are set at init time */ /* no need for synchronization; these variables are set at init time */
guard_size = region.stride - region.size; guard_size = region.stride - region.size;
capacity = region.end + guard_size - region.start; capacity = region.total_size;
capacity -= region.n * (guard_size + TCG_HIGHWATER); capacity -= (region.n - 1) * guard_size;
capacity -= region.n * TCG_HIGHWATER;
return capacity; return capacity;
} }