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util/nvmutil: remove variable nvmPartChanged

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pointless optimisation. we know that when a user requests an
operation that would write, it will probably result in a change.

therefore, this change is the real optimisation. to avoid
writing the same half of a file twice, when using cmd_copy,
we check (in writeGbe) whether gbe part 0 and 1 are the same;
if they are, then we only loop once. this is important, because
otherwise we would call swap() twice.

this means that the optimisations in cmd_copy and cmd_swap must
be removed. the point of this and other changes is to improve
memory safety in nvmutil, so frivolous use of pointers has to go.

Signed-off-by: Leah Rowe <leah@libreboot.org>
This commit is contained in:
Leah Rowe
2026-03-03 00:51:10 +00:00
parent dfbb3c5d9e
commit 566ae72ca3
1 changed files with 10 additions and 20 deletions
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util/nvmutil/nvmutil.c
+10 -20
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@@ -42,7 +42,6 @@ uint8_t buf[SIZE_8KB];
uint16_t mac[3] = {0, 0, 0};
size_t partsize;
uint8_t *gbe[2];
uint8_t nvmPartChanged[2] = {0, 0};
int flags, rfd, fd, part, e = 1;
const char *strMac = NULL, *strRMac = "xx:xx:xx:xx:xx:xx", *fname = NULL;
@@ -295,10 +294,6 @@ void
cmd_dump(void)
{
for (int partnum = 0, numInvalid = 0; partnum < 2; partnum++) {
if ((cmd != cmd_dump) && (flags != O_RDONLY) &&
(!nvmPartChanged[partnum]))
continue;
if (!goodChecksum(partnum))
++numInvalid;
@@ -361,9 +356,8 @@ void
cmd_copy(void)
{
err_if(!goodChecksum(part));
gbe[part ^ 1] = gbe[part];
nvmPartChanged[part ^ 1] = 1;
for (int c = 0; c < SIZE_4KB; c++)
gbe[part ^ 1][c] = gbe[part][c];
}
void
@@ -371,11 +365,11 @@ cmd_swap(void) {
err_if(!(goodChecksum(0) || goodChecksum(1)));
errno = 0;
uint8_t *chg = gbe[0];
gbe[0] = gbe[1];
gbe[1] = chg;
nvmPartChanged[0] = nvmPartChanged[1] = 1;
for (int c = 0; c < SIZE_4KB; c++) {
uint8_t chg = gbe[0][c];
gbe[0][c] = gbe[1][c];
gbe[1][c] = chg;
}
}
int
@@ -404,10 +398,7 @@ void
setWord(int pos16, int p, uint16_t val16)
{
check_bounds(pos16, p);
if (((uint16_t *) gbe[p])[pos16] != val16) {
nvmPartChanged[p] = 1;
((uint16_t *) gbe[p])[pos16] = val16;
}
((uint16_t *) gbe[p])[pos16] = val16;
}
void
@@ -422,8 +413,8 @@ check_bounds(int c, int p)
void
writeGbe(void)
{
for (int p = 0; p < 2; p++)
if ((nvmPartChanged[p]) && (flags != O_RDONLY))
if (flags != O_RDONLY)
for (int p = 0; p < 2; p++)
writeGbe_part(p);
err_if(close(fd) == -1);
}
@@ -435,7 +426,6 @@ writeGbe_part(int p)
if(pwrite(fd, (uint8_t *) gbe[p], SIZE_4KB, p * partsize) != SIZE_4KB)
err(set_err(ECANCELED),
"Can't write %d b to '%s' p%d", SIZE_4KB, fname, p);
}
void