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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:28:00 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:28:00 +0000 |
commit | 3565071f226432336a54d0193d729fa4508a3394 (patch) | |
tree | 4cde13f078f84c0a7785d234fd52edce7c90546a /debian/patches-rt/0086-printk-Adjust-mapping-for-32bit-seq-macros.patch | |
parent | Adding upstream version 6.6.15. (diff) | |
download | linux-3565071f226432336a54d0193d729fa4508a3394.tar.xz linux-3565071f226432336a54d0193d729fa4508a3394.zip |
Adding debian version 6.6.15-2.debian/6.6.15-2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | debian/patches-rt/0086-printk-Adjust-mapping-for-32bit-seq-macros.patch | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/debian/patches-rt/0086-printk-Adjust-mapping-for-32bit-seq-macros.patch b/debian/patches-rt/0086-printk-Adjust-mapping-for-32bit-seq-macros.patch new file mode 100644 index 0000000000..d6ff341f46 --- /dev/null +++ b/debian/patches-rt/0086-printk-Adjust-mapping-for-32bit-seq-macros.patch @@ -0,0 +1,71 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Thu, 7 Dec 2023 14:15:15 +0000 +Subject: [PATCH 086/134] printk: Adjust mapping for 32bit seq macros +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz + +Note: This change only applies to 32bit architectures. On 64bit + architectures the macros are NOPs. + +__ulseq_to_u64seq() computes the upper 32 bits of the passed +argument value (@ulseq). The upper bits are derived from a base +value (@rb_next_seq) in a way that assumes @ulseq represents a +64bit number that is less than or equal to @rb_next_seq. + +Until now this mapping has been correct for all call sites. However, +in a follow-up commit, values of @ulseq will be passed in that are +higher than the base value. This requires a change to how the 32bit +value is mapped to a 64bit sequence number. + +Rather than mapping @ulseq such that the base value is the end of a +32bit block, map @ulseq such that the base value is in the middle of +a 32bit block. This allows supporting 31 bits before and after the +base value, which is deemed acceptable for the console sequence +number during runtime. + +Here is an example to illustrate the previous and new mappings. + +For a base value (@rb_next_seq) of 2 2000 0000... + +Before this change the range of possible return values was: + +1 2000 0001 to 2 2000 0000 + +__ulseq_to_u64seq(1fff ffff) => 2 1fff ffff +__ulseq_to_u64seq(2000 0000) => 2 2000 0000 +__ulseq_to_u64seq(2000 0001) => 1 2000 0001 +__ulseq_to_u64seq(9fff ffff) => 1 9fff ffff +__ulseq_to_u64seq(a000 0000) => 1 a000 0000 +__ulseq_to_u64seq(a000 0001) => 1 a000 0001 + +After this change the range of possible return values are: +1 a000 0001 to 2 a000 0000 + +__ulseq_to_u64seq(1fff ffff) => 2 1fff ffff +__ulseq_to_u64seq(2000 0000) => 2 2000 0000 +__ulseq_to_u64seq(2000 0001) => 2 2000 0001 +__ulseq_to_u64seq(9fff ffff) => 2 9fff ffff +__ulseq_to_u64seq(a000 0000) => 2 a000 0000 +__ulseq_to_u64seq(a000 0001) => 1 a000 0001 + +[ john.ogness: Rewrite commit message. ] + +Reported-by: Francesco Dolcini <francesco@dolcini.it> +Reported-by: kernel test robot <oliver.sang@intel.com> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/printk/printk_ringbuffer.h | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +--- a/kernel/printk/printk_ringbuffer.h ++++ b/kernel/printk/printk_ringbuffer.h +@@ -407,7 +407,7 @@ static inline u64 __ulseq_to_u64seq(stru + * Also the access to the ring buffer is always safe. + */ + rb_next_seq = prb_next_seq(rb); +- seq = rb_next_seq - ((u32)rb_next_seq - ulseq); ++ seq = rb_next_seq - (s32)((u32)rb_next_seq - ulseq); + + return seq; + } |