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hw/ppc/ppc405_uc.c: Avoid integer overflows 

When performing clock calculations, the ppc405_uc code
has several places where it multiplies together two
32-bit variables and assigns the result to a 64-bit
variable. This doesn't quite do what is intended because
C will compute a 32-bit multiply result. Add casts to
ensure we don't truncate the result.

(Spotted by Coverity, CID 1005504, 1005505.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Peter Maydell 2017-02-21 13:33:41 +00:00 committed by David Gibson
parent df58713396
commit fb6971c110
1 changed files with 3 additions and 3 deletions
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6
hw/ppc/ppc405_uc.c
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@ -1881,7 +1881,7 @@ static void ppc405cr_clk_setup (ppc405cr_cpc_t *cpc)
D1 = (((cpc->pllmr >> 20) - 1) & 0xF) + 1; /* FBDV */ D1 = (((cpc->pllmr >> 20) - 1) & 0xF) + 1; /* FBDV */
D2 = 8 - ((cpc->pllmr >> 16) & 0x7); /* FWDVA */ D2 = 8 - ((cpc->pllmr >> 16) & 0x7); /* FWDVA */
M = D0 * D1 * D2; M = D0 * D1 * D2;
VCO_out = cpc->sysclk * M; VCO_out = (uint64_t)cpc->sysclk * M;
if (VCO_out < 400000000 || VCO_out > 800000000) { if (VCO_out < 400000000 || VCO_out > 800000000) {
/* PLL cannot lock */ /* PLL cannot lock */
cpc->pllmr &= ~0x80000000; cpc->pllmr &= ~0x80000000;
@ -1892,7 +1892,7 @@ static void ppc405cr_clk_setup (ppc405cr_cpc_t *cpc)
/* Bypass PLL */ /* Bypass PLL */
bypass_pll: bypass_pll:
M = D0; M = D0;
PLL_out = cpc->sysclk * M; PLL_out = (uint64_t)cpc->sysclk * M;
} }
CPU_clk = PLL_out; CPU_clk = PLL_out;
if (cpc->cr1 & 0x00800000) if (cpc->cr1 & 0x00800000)
@ -2242,7 +2242,7 @@ static void ppc405ep_compute_clocks (ppc405ep_cpc_t *cpc)
#ifdef DEBUG_CLOCKS_LL #ifdef DEBUG_CLOCKS_LL
printf("FWDA %01" PRIx32 " %d\n", (cpc->pllmr[1] >> 16) & 0x7, D); printf("FWDA %01" PRIx32 " %d\n", (cpc->pllmr[1] >> 16) & 0x7, D);
#endif #endif
VCO_out = cpc->sysclk * M * D; VCO_out = (uint64_t)cpc->sysclk * M * D;
if (VCO_out < 500000000UL || VCO_out > 1000000000UL) { if (VCO_out < 500000000UL || VCO_out > 1000000000UL) {
/* Error - unlock the PLL */ /* Error - unlock the PLL */
printf("VCO out of range %" PRIu64 "\n", VCO_out); printf("VCO out of range %" PRIu64 "\n", VCO_out);