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authorAlex Bennée <alex.bennee@linaro.org>2022-02-25 17:20:20 +0000
committerAlex Bennée <alex.bennee@linaro.org>2022-02-28 16:42:35 +0000
commit5fc983af8b20d69279f819efef2b340565d0e9a3 (patch)
tree3cfdbdf77a57ce019760f325aaef7c1ef3db5ba5 /semihosting
parent04e90c1313fc6422fc3a5066fcc84ef3ef030ebf (diff)
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semihosting/arm-compat: replace heuristic for softmmu SYS_HEAPINFO
The previous numbers were a guess at best and rather arbitrary without taking into account anything that might be loaded. Instead of using guesses based on the state of registers implement a new function that: a) scans the MemoryRegions for the largest RAM block b) iterates through all "ROM" blobs looking for the biggest gap The "ROM" blobs include all code loaded via -kernel and the various -device loader techniques. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Cc: Andrew Strauss <astrauss11@gmail.com> Cc: Keith Packard <keithp@keithp.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Message-Id: <20220225172021.3493923-18-alex.bennee@linaro.org>
Diffstat (limited to 'semihosting')
-rw-r--r--semihosting/arm-compat-semi.c124
1 files changed, 63 insertions, 61 deletions
diff --git a/semihosting/arm-compat-semi.c b/semihosting/arm-compat-semi.c
index 37963be..7a51fd0 100644
--- a/semihosting/arm-compat-semi.c
+++ b/semihosting/arm-compat-semi.c
@@ -44,6 +44,7 @@
#define COMMON_SEMI_HEAP_SIZE (128 * 1024 * 1024)
#else
#include "qemu/cutils.h"
+#include "hw/loader.h"
#ifdef TARGET_ARM
#include "hw/arm/boot.h"
#endif
@@ -144,33 +145,69 @@ typedef struct GuestFD {
static GArray *guestfd_array;
#ifndef CONFIG_USER_ONLY
-#include "exec/address-spaces.h"
-/*
- * Find the base of a RAM region containing the specified address
+
+/**
+ * common_semi_find_bases: find information about ram and heap base
+ *
+ * This function attempts to provide meaningful numbers for RAM and
+ * HEAP base addresses. The rambase is simply the lowest addressable
+ * RAM position. For the heapbase we ask the loader to scan the
+ * address space and the largest available gap by querying the "ROM"
+ * regions.
+ *
+ * Returns: a structure with the numbers we need.
*/
-static inline hwaddr
-common_semi_find_region_base(hwaddr addr)
+
+typedef struct LayoutInfo {
+ target_ulong rambase;
+ size_t ramsize;
+ hwaddr heapbase;
+ hwaddr heaplimit;
+} LayoutInfo;
+
+static bool find_ram_cb(Int128 start, Int128 len, const MemoryRegion *mr,
+ hwaddr offset_in_region, void *opaque)
{
- MemoryRegion *subregion;
+ LayoutInfo *info = (LayoutInfo *) opaque;
+ uint64_t size = int128_get64(len);
+
+ if (!mr->ram || mr->readonly) {
+ return false;
+ }
+
+ if (size > info->ramsize) {
+ info->rambase = int128_get64(start);
+ info->ramsize = size;
+ }
+
+ /* search exhaustively for largest RAM */
+ return false;
+}
+
+static LayoutInfo common_semi_find_bases(CPUState *cs)
+{
+ FlatView *fv;
+ LayoutInfo info = { 0, 0, 0, 0 };
+
+ RCU_READ_LOCK_GUARD();
+
+ fv = address_space_to_flatview(cs->as);
+ flatview_for_each_range(fv, find_ram_cb, &info);
/*
- * Find the chunk of R/W memory containing the address. This is
- * used for the SYS_HEAPINFO semihosting call, which should
- * probably be using information from the loaded application.
+ * If we have found the RAM lets iterate through the ROM blobs to
+ * work out the best place for the remainder of RAM and split it
+ * equally between stack and heap.
*/
- QTAILQ_FOREACH(subregion, &get_system_memory()->subregions,
- subregions_link) {
- if (subregion->ram && !subregion->readonly) {
- Int128 top128 = int128_add(int128_make64(subregion->addr),
- subregion->size);
- Int128 addr128 = int128_make64(addr);
- if (subregion->addr <= addr && int128_lt(addr128, top128)) {
- return subregion->addr;
- }
- }
+ if (info.rambase || info.ramsize > 0) {
+ RomGap gap = rom_find_largest_gap_between(info.rambase, info.ramsize);
+ info.heapbase = gap.base;
+ info.heaplimit = gap.base + gap.size;
}
- return 0;
+
+ return info;
}
+
#endif
#ifdef TARGET_ARM
@@ -204,28 +241,6 @@ common_semi_sys_exit_extended(CPUState *cs, int nr)
return (nr == TARGET_SYS_EXIT_EXTENDED || is_a64(cs->env_ptr));
}
-#ifndef CONFIG_USER_ONLY
-#include "hw/arm/boot.h"
-static inline target_ulong
-common_semi_rambase(CPUState *cs)
-{
- CPUArchState *env = cs->env_ptr;
- const struct arm_boot_info *info = env->boot_info;
- target_ulong sp;
-
- if (info) {
- return info->loader_start;
- }
-
- if (is_a64(env)) {
- sp = env->xregs[31];
- } else {
- sp = env->regs[13];
- }
- return common_semi_find_region_base(sp);
-}
-#endif
-
#endif /* TARGET_ARM */
#ifdef TARGET_RISCV
@@ -251,17 +266,6 @@ common_semi_sys_exit_extended(CPUState *cs, int nr)
return (nr == TARGET_SYS_EXIT_EXTENDED || sizeof(target_ulong) == 8);
}
-#ifndef CONFIG_USER_ONLY
-
-static inline target_ulong
-common_semi_rambase(CPUState *cs)
-{
- RISCVCPU *cpu = RISCV_CPU(cs);
- CPURISCVState *env = &cpu->env;
- return common_semi_find_region_base(env->gpr[xSP]);
-}
-#endif
-
#endif
/*
@@ -1165,12 +1169,12 @@ target_ulong do_common_semihosting(CPUState *cs)
case TARGET_SYS_HEAPINFO:
{
target_ulong retvals[4];
- target_ulong limit;
int i;
#ifdef CONFIG_USER_ONLY
TaskState *ts = cs->opaque;
+ target_ulong limit;
#else
- target_ulong rambase = common_semi_rambase(cs);
+ LayoutInfo info = common_semi_find_bases(cs);
#endif
GET_ARG(0);
@@ -1201,12 +1205,10 @@ target_ulong do_common_semihosting(CPUState *cs)
retvals[2] = ts->stack_base;
retvals[3] = 0; /* Stack limit. */
#else
- limit = current_machine->ram_size;
- /* TODO: Make this use the limit of the loaded application. */
- retvals[0] = rambase + limit / 2;
- retvals[1] = rambase + limit;
- retvals[2] = rambase + limit; /* Stack base */
- retvals[3] = rambase; /* Stack limit. */
+ retvals[0] = info.heapbase; /* Heap Base */
+ retvals[1] = info.heaplimit; /* Heap Limit */
+ retvals[2] = info.heaplimit; /* Stack base */
+ retvals[3] = info.heapbase; /* Stack limit. */
#endif
for (i = 0; i < ARRAY_SIZE(retvals); i++) {