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semihosting: Split out guestfd.c

Browse source 
In arm-compat-semi.c, we have more advanced treatment of
guest file descriptors than we do in other implementations.
Split out GuestFD and related functions to a new file so
that they can be shared.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-04-27 21:38:02 -07:00
parent 3d5e2b4f26
commit 1c6ff7205b
10 changed files with 233 additions and 142 deletions
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164
semihosting/arm-compat-semi.c
View file

@ -32,12 +32,13 @@
*/
#include "qemu/osdep.h"
#include "semihosting/semihost.h"
#include "semihosting/console.h"
#include "semihosting/common-semi.h"
#include "semihosting/guestfd.h"
#include "qemu/timer.h"
#include "exec/gdbstub.h"
#ifdef CONFIG_USER_ONLY
#include "qemu.h"
@ -123,27 +124,6 @@ static int open_modeflags[12] = {
O_RDWR | O_CREAT | O_APPEND | O_BINARY
};
typedef enum GuestFDType {
GuestFDUnused = 0,
GuestFDHost = 1,
GuestFDGDB = 2,
GuestFDFeatureFile = 3,
} GuestFDType;
/*
* Guest file descriptors are integer indexes into an array of
* these structures (we will dynamically resize as necessary).
*/
typedef struct GuestFD {
GuestFDType type;
union {
int hostfd;
target_ulong featurefile_offset;
};
} GuestFD;
static GArray *guestfd_array;
#ifndef CONFIG_USER_ONLY
/**
@ -268,98 +248,6 @@ common_semi_sys_exit_extended(CPUState *cs, int nr)
#endif
/*
* Allocate a new guest file descriptor and return it; if we
* couldn't allocate a new fd then return -1.
* This is a fairly simplistic implementation because we don't
* expect that most semihosting guest programs will make very
* heavy use of opening and closing fds.
*/
static int alloc_guestfd(void)
{
guint i;
if (!guestfd_array) {
/* New entries zero-initialized, i.e. type GuestFDUnused */
guestfd_array = g_array_new(FALSE, TRUE, sizeof(GuestFD));
}
/* SYS_OPEN should return nonzero handle on success. Start guestfd from 1 */
for (i = 1; i < guestfd_array->len; i++) {
GuestFD *gf = &g_array_index(guestfd_array, GuestFD, i);
if (gf->type == GuestFDUnused) {
return i;
}
}
/* All elements already in use: expand the array */
g_array_set_size(guestfd_array, i + 1);
return i;
}
/*
* Look up the guestfd in the data structure; return NULL
* for out of bounds, but don't check whether the slot is unused.
* This is used internally by the other guestfd functions.
*/
static GuestFD *do_get_guestfd(int guestfd)
{
if (!guestfd_array) {
return NULL;
}
if (guestfd <= 0 || guestfd >= guestfd_array->len) {
return NULL;
}
return &g_array_index(guestfd_array, GuestFD, guestfd);
}
/*
* Associate the specified guest fd (which must have been
* allocated via alloc_fd() and not previously used) with
* the specified host/gdb fd.
*/
static void associate_guestfd(int guestfd, int hostfd)
{
GuestFD *gf = do_get_guestfd(guestfd);
assert(gf);
gf->type = use_gdb_syscalls() ? GuestFDGDB : GuestFDHost;
gf->hostfd = hostfd;
}
/*
* Deallocate the specified guest file descriptor. This doesn't
* close the host fd, it merely undoes the work of alloc_fd().
*/
static void dealloc_guestfd(int guestfd)
{
GuestFD *gf = do_get_guestfd(guestfd);
assert(gf);
gf->type = GuestFDUnused;
}
/*
* Given a guest file descriptor, get the associated struct.
* If the fd is not valid, return NULL. This is the function
* used by the various semihosting calls to validate a handle
* from the guest.
* Note: calling alloc_guestfd() or dealloc_guestfd() will
* invalidate any GuestFD* obtained by calling this function.
*/
static GuestFD *get_guestfd(int guestfd)
{
GuestFD *gf = do_get_guestfd(guestfd);
if (!gf || gf->type == GuestFDUnused) {
return NULL;
}
return gf;
}
/*
* The semihosting API has no concept of its errno being thread-safe,
* as the API design predates SMP CPUs and was intended as a simple
@ -665,22 +553,13 @@ static const uint8_t featurefile_data[] = {
SH_EXT_EXIT_EXTENDED | SH_EXT_STDOUT_STDERR, /* Feature byte 0 */
};
static void init_featurefile_guestfd(int guestfd)
{
GuestFD *gf = do_get_guestfd(guestfd);
assert(gf);
gf->type = GuestFDFeatureFile;
gf->featurefile_offset = 0;
}
static uint32_t featurefile_closefn(CPUState *cs, GuestFD *gf)
static uint32_t staticfile_closefn(CPUState *cs, GuestFD *gf)
{
/* Nothing to do */
return 0;
}
static uint32_t featurefile_writefn(CPUState *cs, GuestFD *gf,
static uint32_t staticfile_writefn(CPUState *cs, GuestFD *gf,
target_ulong buf, uint32_t len)
{
/* This fd can never be open for writing */
@ -689,7 +568,7 @@ static uint32_t featurefile_writefn(CPUState *cs, GuestFD *gf,
return set_swi_errno(cs, -1);
}
static uint32_t featurefile_readfn(CPUState *cs, GuestFD *gf,
static uint32_t staticfile_readfn(CPUState *cs, GuestFD *gf,
target_ulong buf, uint32_t len)
{
CPUArchState *env = cs->env_ptr;
@ -703,11 +582,11 @@ static uint32_t featurefile_readfn(CPUState *cs, GuestFD *gf,
}
for (i = 0; i < len; i++) {
if (gf->featurefile_offset >= sizeof(featurefile_data)) {
if (gf->staticfile.off >= gf->staticfile.len) {
break;
}
s[i] = featurefile_data[gf->featurefile_offset];
gf->featurefile_offset++;
s[i] = gf->staticfile.data[gf->staticfile.off];
gf->staticfile.off++;
}
unlock_user(s, buf, len);
@ -716,21 +595,21 @@ static uint32_t featurefile_readfn(CPUState *cs, GuestFD *gf,
return len - i;
}
static uint32_t featurefile_isattyfn(CPUState *cs, GuestFD *gf)
static uint32_t staticfile_isattyfn(CPUState *cs, GuestFD *gf)
{
return 0;
}
static uint32_t featurefile_seekfn(CPUState *cs, GuestFD *gf,
static uint32_t staticfile_seekfn(CPUState *cs, GuestFD *gf,
target_ulong offset)
{
gf->featurefile_offset = offset;
gf->staticfile.off = offset;
return 0;
}
static uint32_t featurefile_flenfn(CPUState *cs, GuestFD *gf)
static uint32_t staticfile_flenfn(CPUState *cs, GuestFD *gf)
{
return sizeof(featurefile_data);
return gf->staticfile.len;
}
typedef struct GuestFDFunctions {
@ -759,13 +638,13 @@ static const GuestFDFunctions guestfd_fns[] = {
.seekfn = gdb_seekfn,
.flenfn = gdb_flenfn,
},
[GuestFDFeatureFile] = {
.closefn = featurefile_closefn,
.writefn = featurefile_writefn,
.readfn = featurefile_readfn,
.isattyfn = featurefile_isattyfn,
.seekfn = featurefile_seekfn,
.flenfn = featurefile_flenfn,
[GuestFDStatic] = {
.closefn = staticfile_closefn,
.writefn = staticfile_writefn,
.readfn = staticfile_readfn,
.isattyfn = staticfile_isattyfn,
.seekfn = staticfile_seekfn,
.flenfn = staticfile_flenfn,
},
};
@ -886,7 +765,8 @@ target_ulong do_common_semihosting(CPUState *cs)
errno = EACCES;
return set_swi_errno(cs, -1);
}
init_featurefile_guestfd(guestfd);
staticfile_guestfd(guestfd, featurefile_data,
sizeof(featurefile_data));
return guestfd;
}