Hi Lorenzo,
On 9/11/24 5:34 PM, Lorenzo Stoakes wrote:
Avoid nested min()/max() which results in egregious macro expansion.
This issue was introduced by commit 867046cc7027 ("minmax: relax check to allow comparison between unsigned arguments and signed constants") [2].
Work has been done to address the issue of egregious min()/max() macro expansion in commit 22f546873149 ("minmax: improve macro expansion and type checking") and related, however it appears that some issues remain on more tightly constrained systems.
Adjust a few known-bad cases of deeply nested macros to avoid doing so to mitigate this. Porting the patch first proposed in [1] to Linus's tree.
Running an allmodconfig build using the methodology described in [2] we observe a 35 MiB reduction in generated code.
The difference is much more significant prior to recent minmax fixes which were not backported. As per [1] prior these the reduction is more like 200 MiB.
This resolves an issue with slackware 15.0 32-bit compilation as reported by Richard Narron.
Presumably the min/max fixups would be difficult to backport, this patch should be easier and fix's Richard's problem in 5.15.
Reported-by: Richard Narron richard@aaazen.com Closes: https://lore.kernel.org/all/4a5321bd-b1f-1832-f0c-cea8694dc5aa@aaazen.com/ Fixes: 867046cc7027 ("minmax: relax check to allow comparison between unsigned arguments and signed constants") Cc: stable@vger.kernel.org Signed-off-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com
Thank you for your patch.
I must say that I'm not a fan of that this is patching 3 totally unrelated files here in a single patch.
This is e.g. going to be a problem if we need to revert one of the changes because of regressions...
So I would prefer this to be split into 3 patches.
One review comment for the atomisp bits inline / below.
drivers/net/ethernet/marvell/mvpp2/mvpp2.h | 2 +- .../staging/media/atomisp/pci/sh_css_frac.h | 26 ++++++++++++++----- include/linux/skbuff.h | 6 ++++- 3 files changed, 25 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h index e809f91c08fb..8b431f90efc3 100644 --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h @@ -23,7 +23,7 @@ /* The PacketOffset field is measured in units of 32 bytes and is 3 bits wide,
- so the maximum offset is 7 * 32 = 224
*/ -#define MVPP2_SKB_HEADROOM min(max(XDP_PACKET_HEADROOM, NET_SKB_PAD), 224) +#define MVPP2_SKB_HEADROOM clamp_t(int, XDP_PACKET_HEADROOM, NET_SKB_PAD, 224)
#define MVPP2_XDP_PASS 0 #define MVPP2_XDP_DROPPED BIT(0) diff --git a/drivers/staging/media/atomisp/pci/sh_css_frac.h b/drivers/staging/media/atomisp/pci/sh_css_frac.h index b90b5b330dfa..a973394c5bc0 100644 --- a/drivers/staging/media/atomisp/pci/sh_css_frac.h +++ b/drivers/staging/media/atomisp/pci/sh_css_frac.h @@ -32,12 +32,24 @@ #define uISP_VAL_MAX ((unsigned int)((1 << uISP_REG_BIT) - 1))
/* a:fraction bits for 16bit precision, b:fraction bits for ISP precision */ -#define sDIGIT_FITTING(v, a, b) \
- min_t(int, max_t(int, (((v) >> sSHIFT) >> max(sFRACTION_BITS_FITTING(a) - (b), 0)), \
sISP_VAL_MIN), sISP_VAL_MAX)-#define uDIGIT_FITTING(v, a, b) \
- min((unsigned int)max((unsigned)(((v) >> uSHIFT) \
uISP_VAL_MIN), uISP_VAL_MAX)+static inline int sDIGIT_FITTING(short v, int a, int b) +{
drivers/staging/media/atomisp/pci/isp/kernels/s3a/s3a_1.0/ia_css_s3a.host.c
calls this with ia_css_3a_config.af_fir1_coef / .af_fir2_coef as first argument those are of the ia_css_s0_15 type which is:
/* Signed fixed point value, 0 integer bits, 15 fractional bits */ typedef s32 ia_css_s0_15;
please replace the "short v" with "int v"
I think that you can then also replace clamp_t() with clamp()
- int fit_shift = sFRACTION_BITS_FITTING(a) - b;
- v >>= sSHIFT;
- v >>= fit_shift > 0 ? fit_shift : 0;
- return clamp_t(int, v, sISP_VAL_MIN, sISP_VAL_MAX);
+}
+static inline unsigned int uDIGIT_FITTING(unsigned int v, int a, int b) +{
- int fit_shift = uFRACTION_BITS_FITTING(a) - b;
- v >>= uSHIFT;
- v >>= fit_shift > 0 ? fit_shift : 0;
- return clamp_t(unsigned int, v, uISP_VAL_MIN, uISP_VAL_MAX);
+}
Regular clamp() should work here ? all parameters are already unsigned ints.
Regards,
Hans
#endif /* __SH_CSS_FRAC_H */ diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 29c3ea5b6e93..d53b296df504 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3164,7 +3164,11 @@ static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
- NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
*/ #ifndef NET_SKB_PAD -#define NET_SKB_PAD max(32, L1_CACHE_BYTES) +#if L1_CACHE_BYTES < 32 +#define NET_SKB_PAD 32 +#else +#define NET_SKB_PAD L1_CACHE_BYTES +#endif #endif
int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2.46.0