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[gamecode] Rework PR_RESET_PARAMS to use PR_SetupParams

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PR_SetupParams is new and sets up the parameter pointers so older code
that expects only up to 8 parameter will work with both v6p and Ruamoko
progs without having to check what progs are running. PR_SetupParams is
useful even when Ruamoko progs are expected as it reserves the required
space (respecting alignment) on the stack and returns a pointer to the
top (bottom? confusing) of the stack. PR_PushFrame and PR_PopFrame
need to be used around PR_SetupParams, regardless of using temp strings,
to avoid a stack leak (need to do an audit).
This commit is contained in:
Bill Currie 2022-01-24 12:50:15 +09:00
parent 1f802716e1
commit 00b7bced7f
2 changed files with 69 additions and 6 deletions
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42
include/QF/progs.h
View file

@ -82,15 +82,13 @@ void PR_RunError (progs_t *pr, const char *error, ...) __attribute__((format(PRI
\warning Failure to use this macro before assigning to the P_* macros can
cause corruption of the VM data due to "register" based calling. Can be
safely ignored for parameterless functions, or forwarding parameters
though a builtin.
though a builtin. However, it is ok (and encouraged) to call
PR_SetupParams instead, as this macro calls PR_SetupParams with
PR_MAX_PARAMS and 1 for the alignment.
\hideinitializer
*/
#define PR_RESET_PARAMS(pr) \
do { \
(pr)->pr_params[0] = (pr)->pr_real_params[0]; \
(pr)->pr_params[1] = (pr)->pr_real_params[1]; \
} while (0)
#define PR_RESET_PARAMS(pr) PR_SetupParams (pr, PR_MAX_PARAMS, 1)
/** \name Detouring Function Calls
@ -155,6 +153,38 @@ void PR_RestoreParams (progs_t *pr, pr_stashed_params_t *params);
*/
void PR_PushFrame (progs_t *pr);
/** Reserve space on the data stack and set up the param pointers.
For v6p progs, this only sets up the param pointers as v6p progs do not
have a data stack.
For Ruamoko progs, space for at least \a num_params (each being 4 words)
is created on the stack, with a minimum alignment of min_alignment words,
or 4, whichever is larger.
\param pr pointer to ::progs_t VM struct
\param num_params Number of parameter slots needed for the function call.
Each slot is 4 words. dvec4 and lvec4 parameters require
8 words and must be 8-word aligned. dvec3 and lvec3
also require 8 words due to the minimum 4 word alignment,
but have no alignment requirements themselves. Be sure to
take this into account in size calculations.
\param min_alignment Minimum number of words to which the stack will be
aligned. Must be a power of two. Note that when passing
dvec4 or lvec4 parameters, they have a hardware-enforced
requirement of 8 word alignment. This means that for
something like (int, lvec4), there will be an unused
parameter slot between the int and the lvec4.
Ignored for v6p progs.
\return Pointer to the base of the created parameter area. For
v6p progs, this is just .param_0, but for Ruamoko progs
this will be the current top of the the data stack after
adjustment for the parameter space.
\note Attempting to pass more than PR_MAX_PARAMS parameters to v6p progs
is a hard error.
*/
pr_type_t *PR_SetupParams (progs_t *pr, int num_params, int min_alignment);
/** Pop an execution frame from the VM stack. Restores execution state. Also
frees any temporary strings allocated in this frame (via
PR_FreeTempStrings()).

33
libs/gamecode/pr_exec.c
View file

@ -458,6 +458,9 @@ PR_CallFunction (progs_t *pr, pr_func_t fnum, pr_type_t *return_ptr)
static void
check_stack_pointer (progs_t *pr, pr_ptr_t stack, int size)
{
if (stack & 3) {
PR_RunError (pr, "Progs stack not aligned");
}
if (stack < pr->stack_bottom) {
PR_RunError (pr, "Progs stack overflow");
}
@ -466,6 +469,36 @@ check_stack_pointer (progs_t *pr, pr_ptr_t stack, int size)
}
}
VISIBLE pr_type_t *
PR_SetupParams (progs_t *pr, int num_params, int min_alignment)
{
if (pr->progs->version < PROG_VERSION) {
if (num_params > PR_MAX_PARAMS) {
PR_Error (pr, "attempt to settup more than %d params",
PR_MAX_PARAMS);
}
pr->pr_params[0] = pr->pr_real_params[0];
pr->pr_params[1] = pr->pr_real_params[1];
return pr->pr_real_params[0];
}
int offset = num_params * 4;
if (min_alignment < 4) {
min_alignment = 4;
}
pr_ptr_t mask = ~(min_alignment - 1);
pr_ptr_t stack = (*pr->globals.stack - offset) & mask;
if (pr_boundscheck->int_val) {
check_stack_pointer (pr, stack, 0);
}
*pr->globals.stack = stack;
pr->pr_params[0] = pr->pr_globals + stack;
num_params = min (num_params, PR_MAX_PARAMS);
for (int i = 1; i < num_params; i++) {
pr->pr_params[i] = pr->pr_params[0] + i * 4;
}
return pr->pr_params[0];
}
static inline void
pr_memset (pr_type_t *dst, int val, pr_uint_t count)
{